[Association between digestive tract cancer and severity of coronary artery disease]

Objective: To evaluate the association between digestive tract cancer and anatomical severity of coronary artery disease. Methods: This study enrolled 142 patients with digestive tract cancer who underwent coronary angiography in the Department of Cardiology of the First Medical Center of Chinese PLA General Hospital from 2009 to 2020 as the cancer group. The patients in cancer group were matched with 426 non-cancer patients who underwent coronary angiography at our hospital during the same period in a 1∶3 ratio based on gender and age. All enrolled patients had no previous history of percutaneous coronary intervention or coronary artery bypass grafting surgery. The severity of coronary artery disease was documented and assessed using the SYNTAX score based on angiogram. High SYNTAX score (SXhigh) was defined as SYNTAX score≥22 (upper quartile), while low SYNTAX score (SXlow) was SYNTAX score<22. High NLR (NLRhigh) was NLR≥2.287 (median), while low NLR (NLRlow) was NLR<2.287. The association between digestive tract cancer and severity of coronary artery disease was analyzed using logistic regression analysis. Results: This study included a total of 568 patients, with a mean age of (66.6±8.7) years. Among them, 430 patients (75.7%) were male. The cancer group consisted of 142 patients with digestive tract cancers, with a mean age of (66.5±8.4) years. The non-cancer group consisted of 426 patients, with a mean age of (66.7±8.8) years. The proportion of SXhigh in patients with digestive tract cancers (33.1%, 47 patients) was higher than that in non-cancer patients (23.9%, 102 patients) (P=0.032). Compared to non-cancer patients, SXhigh in patients with digestive tract cancers was higher (OR: 1.614, 95%CI: 1.051-2.481, P=0.029). Subgroup analysis stratified by NLR levels revealed that in the NLRhigh group, patients with digestive tract cancers exhibited a higher severity of coronary artery disease compared to non-cancer patients, with an OR of 1.948 (95%CI: 1.005-3.779, P=0.048). In the NLRlow group, there was no significant relationship between digestive tract cancers and the severity of coronary artery disease, with an OR of 1.277 (95%CI: 0.586-2.781, P=0.538). Conclusions: Digestive tract cancer is associated with the severity of coronary artery disease, and patients with digestive tract cancers have a higher risk of severe coronary artery disease than non-cancer patients. Additionally, there is an association between digestive tract cancers and the severity of coronary artery disease under conditions of high levels of inflammation.

[Clinical characteristics and related factors analysis of adrenal crisis occurred in children with primary nephrotic syndrome]

Objective: To investigate the clinical characteristics and related factors of corticosteroid induced adrenal crisis (AC) in children with primary nephrotic syndrome (NS). Methods: Case control study. The case group included 7 children aged 1 to 18 years with NS combined with AC hospitalized in Peking University First Hospital from January 2016 to May 2021 (AC group). According to the ratio of case group: control group 1: 4, 28 children aged 1 to 18 years who were diagnosed with NS without AC during the same period were matched as controls (non-AC group). Clinical data were collected. The clinical characteristics of AC were described. The clinical parameters were compared between the 2 groups by t test, Mann-Whitney U test or Fisher's test. Receiver operating characteristic (ROC) curve was used to analyze the cutoff values of clinical parameters for prediction of AC. Results: The AC group included 4 boys and 3 girls aged 6.9 (4.6, 10.8) years. The non-AC group included 20 boys and 8 girls aged 5.2 (3.3, 8.4) years. All AC events occurred during the relapse of NS with infection. Seven children had gastrointestinal symptoms such as nausea, vomiting and abdominal pain. Six children had poor mental state or impaired consciousness. No significant differences in NS course, corticosteroid treatment course, corticosteroid type, steroid dosage, steroid medication interval, the proportion of gastroenteritis and fever existed between the two groups (all P>0.05). Compared with the non-AC group, the duration from the onset of the relapse of NS until hospitalization in the AC group was significantly shorter (0.2 (0.1, 0.6) vs. 1.0 (0.4, 5.0) month,U=25.50, P=0.005). The 24 h urinary total protein (UTP) level was significantly higher in the AC group (193 (135, 429) vs. 81 (17, 200) mg/kg, U=27.00,P=0.036) than the non-AC group. The serum albumin level in the AC group was significantly lower((13.1±2.1) vs. (24.5±8.7) g/L,t=-6.22,P<0.001) than the non-AC group. There were significantly higher total white blood cell counts ((26±9)×109 vs. (11±5)×109/L,t=4.26,P=0.004), percentage of neutrophils (0.71±0.08 vs. 0.60±0.19,t=2.56,P=0.017) and the proportion of children with C reactive protein level≥8 mg/L (3/7 vs. 0,P=0.005) in the AC group than in the non-AC group. ROC curve analysis showed that the cutoff value of 24 h UTP was 122 mg/(kg·d) with a sensitivity of 100.0% and specificity of 70.4%. The cutoff value of serum albumin was 17.0 g/L with a sensitivity of 100.0% and specificity of 82.1%. Conclusions: Gastrointestinal symptoms and poor mental state were prominent manifestations of AC in children with NS. High 24 h UTP level, low serum albumin level, high peripheral white blood cell counts, high neutrophils percentage, and high C-reactive protein level during the early stage of NS relapse may be related to the occurrence of AC in children with NS.

[Clinical outcomes and influence factors of 435 singleton pregnancies with short cervix]

Objective: To investigate the clinical outcomes of different treatment options on singleton short cervix and its influence factors. Methods: Totally 435 cases of singleton pregnancies who were diagnosed with short cervix (≤25 mm) between 12 to 33⁺⁶ gestational weeks in Peking University First Hospital from January 2018 to December 2018 were enrolled, including 21 cases with cervical length <10 mm, 414 cases with cervical length between 10 to 25 mm. The onset time was <24 gestational weeks in 106 cases, while 104 cases were at 24-29⁺⁶ gestational weeks and 225 cases of ≥30 gestational weeks. Gestational outcomes including delivery before 37 weeks, delivery before 34 weeks, neonatal birth weight (NBW) and adverse neonatal outcome (ANO) were compared among three treatment groups: rest group, progesterone group and cerclage group. Influence factors were also investigated. Results: (1) The incidence of short cervix in pregnancy was 7.07% (435/6 155), while 106 cases were at <24 gestational weeks (1.72%, 106/6 155), 104 cases (1.69%, 104/6 155) at 24-29⁺⁶ gestational weeks and 225 cases (3.66%, 225/6 155) at ≥30 gestational weeks. (2) In the group of cervical length <10 mm, rate of delivery before 37 and 34 weeks were 62% (13/21) and 57% (12/21) respectively. One case of progesterone treatment underwent miscarriage. Compared with rest group (n=8), delivery weeks [28.5 (25.0-40.0) vs 37.0 (28.0-40.0), P=0.020] and NBW [1 245 g (630-3 830 g) vs 2 648 g (1 560-3 830 g), P=0.028] were higher in cerclage group (n=9), while ANO was not statistically different (P>0.05). (3) In the group of cervical length ≥10 mm before 24 gestational weeks, the delivery weeks, incidence of delivery before 34 weeks, adjusted incidence of delivery before 37 weeks, NBW and ANO were not statistically different (P>0.05) among rest group (n=36), progesterone group (n=26) and cerclage group (n=34). In vitro fertilization (OR=11.97, 95%CI: 1.88-76.44, P=0.009), infection (OR=46.03, 95%CI: 5.12-413.58, P=0.001), sludge on sonography (OR=9.87, 95%CI: 1.69-57.60, P=0.011) and history of short cervix (OR=7.24, 95%CI: 1.04-50.24, P=0.045) were independent risk factors of preterm birth. (4) In the group of cervical length ≥10 mm and gestational weeks between 24-29⁺⁶, the delivery weeks, incidence of delivery before 37 weeks, incidence of delivery before 34 weeks, NBW and ANO were not statistically different (P>0.05) among rest group (n=52), progesterone group (n=34) and cerclage group (n=9). Infection was an independent risk factor of preterm birth (OR=56.40, 95%CI: 4.67-680.61, P=0.002). (5) Outcomes of 223 cases were relatively good in the group of cervical length ≥10 mm beyond 30 gestational weeks. The incidence of delivery before 34 weeks was 6.3% (14/223). The delivery weeks, incidence of delivery before 37 and 34 weeks, NBW and ANO were not statistically different (P>0.05) among 3 groups. Infection (OR=10.91, 95%CI: 2.21-53.96, P=0.003) and history of preterm birth (OR=8.63, 95%CI: 1.25-59.65, P=0.029) were independent risk factors of preterm birth. Conclusions: Short cervix is a common complication of pregnancy. Cervical cerclage is related with better outcome for patients with cervical length <10 mm. Neither progesterone nor cervical cerclage improves pregnancy outcome for >10 mm cervical length patients comparing with rest. Infection, sludge, in vitro fertilization, history of short cervix and history of preterm birth are independent risk factors of preterm birth in short cervix pregnancies.

[Risk factors of postoperative complications after laparoscopic surgery for pheochromocytoma]

Objective: To investigate the effects of intraoperative hemodynamic instability on postoperative complications of laparoscopic surgery for pheochromocytoma. Methods: It was a retrospective cohort study. According to inclusion/exclusion criteria, adult patients underwent laparoscopic surgery for pheochromocytoma from January 2005 to December 2017 in Peking University First Hospital were enrolled in this study. Eligible patients were divided into two groups by evidence of postoperative complications to find out the effects of intraoperative hemodynamic instability and its' effects on other prognostic indices. The normally distributed continuous variables were compared between two groups by Student's t test, Mann-Whitney U test were used for the comparison for non-normally distributed continuous variables and χ(2) test for categorical variables. Results: A total of 198 patients were finally enrolled in this study, including 87 males and 111 females with an average age of (47±15) years. Postoperative complications occurred in 17 patients with an incidence of 8.6%, and intraoperative hemodynamic instability occurred in 45 patients (22.7%). It was found that history of stroke[odds ratio (OR)=13.387, 95% confidence interval (CI): 2.284-78.460, P=0.004], intraoperative hemodynamic instability (OR=3.351, 95%CI: 1.119-10.039, P=0.031) and intraoperative positive fluid balance (for each additional 100 ml) (OR=1.087, 95%CI: 1.031-1.146, P=0.002)were the independent risk factors of postoperative complications of laparoscopic surgery for pheochromocytoma. Furthermore, more postoperative complications, higher rate of admitting to ICU and longer hospital stay was found in patients with hemodynamic instability. Conclusion: Intraoperative hemodynamic instability is an independent risk factor for postoperative complications of laparoscopic surgery in patients with pheochromocytoma, and it associates with more postoperative complications and higher rate of admitting to ICU.

[Analysis of neoadjuvant docetaxel, carboplatin and trastuzumab (TCH) in HER-2-positive breast cancer]

Objective: To analyze docetaxel (T) and carboplatin (C) combined with trastuzumab (H) -TCH regimen as neoadjuvant systemic therapy in early breast cancer patients with human epidermal growth factor receptor 2 (HER-2) positive. Methods: From January 2008 to December 2014, the data of patients diagnosed as early breast cancer in Breast Disease Center of Peking University First Hospital were retrospective reviewed. The data of patients with HER-2 positive conducted TCH neoadjuvant therapy and surgery, and with the complete clinicopathological information were analyzed. Results: A total of 77 cases were enrolled in this study. We defined G2+ G3+ G4+ G5 as responsive group according to Miller-Payne grading system, the responsive rate was 84.4% (65/77). The rate of complete pathological remission (pCR) was 39.0% (30/77). The 5-year disease free survival (DFS) was 87.3%, and 5-year overall survival (OS) was 93.6%. There was a significant difference between DFS and OS in the responsive group and non-responsive group (DFS: χ²=6.762, P=0.009; OS: χ²=5.062, P=0.024). Conclusion: TCH is an effective neoadjuvant therapy for patients with HER-2 positive breast cancer, and the toxic and side effects were under control.

[Dynamic investigation of nutritional risk in patients with malignant tumor during hospitalization]

Objective: To prospectively investigate the changes in nutritional status of patients with malignant tumors during hospitalization by using nutritional risk screening (NRS2002), and to analyze the correlation between the nutritional status and clinical outcomes . Methods: This was a prospective and parallel research done by multi-center collaboration from 34 hospitals in China from June to September 2014.Hospitalized patients with malignant tumors inthese departments (Department of Gastroenterology, respiratory medicine, oncology, general surgery, thoracic surgery and geriatrics)were investigated. Only the patients with age≥ 18 years and hospitalization time between 7-30 days were included. During hospitalization, the physical indexes of human bodywere measured, and the NRS 2002 scores, and monitored the nutritional support at the time points of admission and 24 hours before discharge were recorded.And whether there was a nutritional risk in hospitalized patients and its association with clinical outcomes were investigated. Results: A total of 2 402 patients with malignancies were enrolled in this study. Seventy fourpatients who did not complete NRS2002 were eliminated, and 2 328 patients were included. The number of the main diseases was the top five, including 587 cases of colorectal cancer, 567 cases of lung cancer, 564 cases of gastric cancer, 146 cases of esophageal cancer, and 119 cases of liver tumor. At the time of discharge, compared with admission, the BMI, body weight, grip and calf circumferences of patients with malignant tumor were significantly decreased (P<0.05). The total protein, albumin, prealbumin and hemoglobin were significantly lower than those at admission (P<0.05). In 2 328 patients who were completed nutritional risk screening, the rate of malnutrition at admission was 11.1% (BMI =18.5, 258/2 328) and the rate of malnutrition at discharge was 10.9% (BMI =18.5, 254/2 328), there were no significant differences (χ(2)=0.019 7, P=0.888). There were 1 204 patients with nutritional risk at admission (51.7%, NRS2002 score≥3)and 1 352 patients with nutritional risk at discharge (58.1%, NRS2002 score≥3), with significant differences (χ(2)=49.9, P<0.001). The incidence of nutritional risk in patients with colorectal, stomach, and lung tumors at discharge was significantly higher than that at admission (P<0.05). The infective complications and other complications of patients with nutritional risk were significantly greater than those without nutritional risk at admission and at discharge.ICU hospitalization stay of patients with nutritional risk was increased significantly than those without nutritional risk at admission(P=0.042). Hospitalization expenses of patients with nutritional risk was increased significantly than those of patients without nutritional risk at discharge(P<0.01). Conclusion: The patients with malignant tumor have a higher incidence rate of malnutrition at both admission and discharge and malnutritionhas correlation with adverse clinical outcomes.The aboveindicators did not improve significantly at discharge.Doctors should pay more attention to the nutritional status (screening and evaluation)of patients before discharge and use appropriate and adequate nutrition support in order to prevent the weight loss and improve the life quality of patients.

Manipulation of group-velocity-locked vector dissipative solitons and properties of the generated high-order vector soliton structure

Details of various composites of the projections originated from a fundamental group-velocity-locked vector dissipative soliton (GVLVDS) are both experimentally and numerically explored. By combining the projections from the orthogonal polarization components of the GVLVDS, a high-order vector soliton structure with a double-humped pulse profile along one polarization and a single-humped pulse profile along the orthogonal polarization can be observed. Moreover, by de-chirping the composite double-humped pulse, the time separation between the two humps is reduced from 15.36 ps to 1.28 ps, indicating that the frequency chirp of the GVLVDS contributes significantly to the shaping of the double-humped pulse profile.

Multiple generations of high-order orbital angular momentum modes through cascaded third-harmonic generation in a 2D nonlinear photonic crystal

We experimentally demonstrate multiple generations of high-order orbital angular momentum (OAM) modes through third-harmonic generation in a 2D nonlinear photonic crystal. Such third-harmonic generation process is achieved by cascading second-harmonic generation and sum-frequency generation using the non-collinear quasi-phase-matching technique. This technique allows multiple OAM modes with different colors to be simultaneously generated. Moreover, the OAM conservation law guarantees that the topological charge is tripled in the cascaded third-harmonic generation process. Our method is effective for obtaining multiple high-order OAM modes for optical imaging, manipulation, and communications.

[Efficacy of transforaminal endoscopic nerve root decompression in the treatment of degenerative lumbar spinal stenosis]

OBJECTIVE

To evaluate the feasibility of transforaminal endoscopic nerve root decompression for degenerative lumbar spinal stenosis (DLSS).

METHODS

From July 2011 to April 2016, 96 cases of single segment DLSS were involved. All the patients had unilateral lower extremity neurological symptoms, signs, neurogenic intermittent claudication of less than 500 m. Imaging examinations (CT or MRI) or diagnostic nerve root block confirmed single segment degeneration. The mean age was (71.6±5.4) years, male: 55 cases, female: 41 cases. Their intraoperative blood loss, operation time, complications, ambulation time and discharge time were recorded. Leg pain VAS, ODI were used to evaluate the pain and lumbar function of the patients. The clinical efficacy was evaluated by Nakai evaluation.

RESULTS

All the patients were performed endoscopic decompression of the lateral recess and nerve root by removing the ventral part of the superior facet joint, the ligamentum flavum and the intervertebral disc. The decompression range was from the inferior edge of the upper pedicle to the superior edge of the lower pedicle. The nerve root was detected to have no compression and the pulse of nerve root returned to normal. The patient got ambulant on the operation day and discharged if he had no discomfort symptom. In the study, 68 cases got follow up. The mean follow-up time was 12.1 months (6-63 months). The VAS at different follow-up time points was improved relative to the baseline, and the difference was statistically significant (F=491.60, P<0.001). The ODI at different follow-up time points was improved relative to the baseline, and the difference was statistically significant (F=189.91, P<0.001). The excellent and good rates of Nakai evaluation were 79.4% (excellent in 42 cases, good in 12 cases, fair in 10 cases and poor in 4 cases). The mean intraoperative blood loss was (49.29±11.86) mL. The mean operation time was (92.46±21.34) min. The mean ambulation time was 1.8 h. The mean discharge time was 2.3 days. Postoperative epidural hematoma was found in 1 case. Foot drop was found in 1 case. Second stage open surgery was performed in 6 cases.

CONCLUSION

We can apply transforaminal endoscopic decompression for the patients of lumbar spinal stenosis who have unilateral nerve root irritation. Patients with transforaminal endoscopic decompression can get less surgical trauma, quick recovery and obtain good short-term outcome.

[Changes in nutritional status of patients with different diseases during hospitalization]

Objective: To evaluate changes in nutritional status of hospitalized patients with different diseases by subjective global assessment (SGA) and nutritional risk screening (NRS-2002). Methods: A prospective and parallel research done by multi-center collaboration from 34 hospitals in China from June to September 2014. Hospitalized patients with the following diseases were investigated: malignant tumor (2 487 cases), benign disease of the digestive system (1 358 cases), benign disease of the nervous system (1 043 cases), benign bone disease (451 cases), benign disease of the respiratory system(395 cases), cardiovascular disease (227 cases), benign thyroid and breast disease (179 cases), and endocrine disease (149 cases). Patients above the age of 18 and hospitalization time between 7-30 days were included. Physical indexes were measured, the NRS-2002 and SGA scores were recorded, the nutritional support were recorded during hospitalization and 24 hours after discharge from hospital. Measurement data between groups were analyzed using t test or Wilcoxon rank sum test, enumeration data and ranked data between groups were analyzed using chi-square test or Fisher exact test. Results: There were 6 638 cases of hospitalized patients, 3 861 cases were males and 2 777 were females, the male/female ratio was 1.4∶1.0; the median age was 60 years; the median height was 1.66 m; the median weight was 62 kg; the median body mass index (BMI)was 22.89 kg/m(2). At discharge, compared with that of admission, the body weight, BMI, grip strength, upper arm and calf circumferences of patients with malignant tumor were significantly decreased (t=20.15-259.67, all P<0.01); the body weight and calf circumference were significantly decreased (t=35.27, 60.40, P<0.01)of patients with digestive benign disease; the body weight of patients with benign bone diseases was decreased (t=2.12, P=0.033); the body weight, grip strength and upper arm circumference were decreased in patients with benign thyroid and breast disease (t=2.79-10.18, all P<0.01); nutritional risk incidence rate (from NRS-2002) of patients with malignant tumor was significantly higher(χ(2)=21.275, P=0.000); moderate malnutrition (from SGA) incidence rate was significantly higher(χ(2)=62.318, P=0.000; χ(2)=11.312, P<0.01) in patients with malignant tumor and with orthopedics diseases. Compared with that of admission, records of the patients with other diseases had no statistically difference at discharge, no more than 50% of the patients under risk of nutritional deficiency(except those with digestive benign diseases )received nutritional support, while the proportion of non-parenteral nutrition application was higher. Conclusion: The patients with malignant tumor have higher incidence rate of malnutrition on admission and at discharge. Doctors should pay more attention to the nutritional status(screening and evaluation) of patients before discharge and use appropriate and adequate nutrition support in order to prevent the weight loss and improve the life quality of patients.

Controlling thermal emission of phonon by magnetic metasurfaces

Our experiment shows that the thermal emission of phonon can be controlled by magnetic resonance (MR) mode in a metasurface (MTS). Through changing the structural parameter of metasurface, the MR wavelength can be tuned to the phonon resonance wavelength. This introduces a strong coupling between phonon and MR, which results in an anticrossing phonon-plasmons mode. In the process, we can manipulate the polarization and angular radiation of thermal emission of phonon. Such metasurface provides a new kind of thermal emission structures for various thermal management applications.

Scheme for generating distillation-favorable continuous-variable entanglement via three concurrent parametric down-conversions in a single χ(2) nonlinear photonic crystal

We propose to generate a single-mode-squeezing two-mode squeezed vacuum state via a single χ⁽²⁾ nonlinear photonic crystal. The state is favorable for existing Gaussian entanglement distillation schemes, since local squeezing operations can enhance the final entanglement and the success probability. The crystal is designed for enabling three concurrent quasi-phase-matching parametric-down conversions, and hence relieves the auxiliary on-line bi-side local squeezing operations. The compact source opens up a way for continuous-variable quantum technologies and could find more potential applications in future large-scale quantum networks.

Coupled orbital angular momentum conversions in a quasi-periodically poled LiTaO₃ crystal

We experimentally demonstrate the orbital angular momentum (OAM) conversion by the coupled nonlinear optical processes in a quasi-periodically poled LiTaO3 crystal. In such a crystal, third-harmonic generation (THG) is realized by the coupled second-harmonic generation (SHG) and sum-frequency generation (SFG) processes, i.e., SHG is dependent on SFG and vice versa. The OAMs of the interacting waves are proved to be conserved in such coupled nonlinear optical processes. As we increase the input OAM in the experiment, the conversion efficiency decreases because of the reduced fundamental power density. Our results provide better understanding for the OAM conversions, which can be used to efficiently produce an optical OAM state at a short wavelength.

Simultaneous directional emissions of multiple quantum emitters with cross plasmonic antenna

We introduce a cross plasmonic antenna (CPA) for the system of multiple quantum emitters (QEs) with different emission wavelengths, where the excitation light scattering and emission fluorescence of different QEs are spatially separated in four different directions. By considering the CPA as oscillating dipoles, this phenomenon is attributed to the phase differences between them. The enhancement for QEs are very strong in correponding directions. In addition, the fluorescence is strongly polarized. By adding a silver plate as substrate, the directivity can be further tuned in the whole upper half space. Our result shows that the CPA is promising for realization of an efficient, directional and strongly polarized nano-scale light source, which will have potential application in Nano-Optics.

Highly effective degradation of sodium dodecylbenzene sulphonate and synthetic greywater by Fenton-like reaction over zerovalent iron-based catalyst

There is an increasing interest to recycle greywater for meeting non-portable water demand. However, linear alkylbenzene sulphonates (a form of anionic surfactants) that are commonly found in greywater are less biodegradable at moderate to high concentrations. A fenton-like system is a relatively economic advanced oxidation process that can potentially be used for surfactant degradation in greywater treatment. This study investigated the feasibility of zerovalent iron (ZVI)-mediated Fenton's oxidation of sodium dodecylbenzene sulphonate (SDBS) using Fe0/H2O2 and Fe2+/Fe0/H2O2 systems under a range of operating conditions. For the Fe0/H2O2 binary system, the initial pH value and Fe0 dosage played important roles in final degradation efficiency. For the Fe2+/Fe0/H2O2 ternary systems, a small amount of Fe2+ (0.5-1.7 mM) contributed a synergistic effect to promote iron recycling and SDBS degradation. Approximately, 90% of SDBS mineralization efficiency was accomplished within 15 min at a pH range from 3.0 to 6.5, using 18 mM Fe0 and 15 mM H2O2. However, the removal kinetics was rate-limited by Fe2+ dissolution from the ZVI surfaces. The Fenton-like process of the Fe2+/Fe0/H2O2 ternary system also presents a promising treatment method for synthetic greywater, in which 90% TOC removal was achieved within the first 10 min; 78% COD and 91% BOD5 were achieved after 120 min of reaction.

Orbital angular momentum entanglement via fork-poling nonlinear photonic crystals

We report a compact scheme for the generation and manipulation of photon pairs entangled in the orbital angular momentum (OAM) from the fork-poling quadratic nonlinear crystal. The χ⁽²⁾-modulation in this crystal is designed for fulfilling a tilted quasi-phase-matching geometry to ensure the efficient generation of entangled photons as well as for transferring of topological charge of the crystal to the photon pairs. Numerical results show that the OAM of photon pair is anti-correlated and the degree of OAM entanglement can be enhanced by modulating the topological charge of crystal, which indicates a feasible extension to high-dimensional OAM entanglement. These studies suggest that the fork-poling nonlinear photonic crystal a unique platform for compact generation and manipulation of high-dimensional and high-order OAM entanglement, which may have potential applications in quantum communication, quantum cryptography and quantum remote sensing.

On-chip generation and manipulation of entangled photons based on reconfigurable lithium-niobate waveguide circuits

A consequent tendency toward high-performance quantum information processing is to develop the fully integrated photonic chip. Here, we report the on-chip generation and manipulation of entangled photons based on reconfigurable lithium-niobate waveguide circuits. By introducing a periodically poled structure into the waveguide circuits, two individual photon-pair sources with a controllable electro-optic phase shift are produced within a Hong-Ou-Mandel interferometer, resulting in a deterministically separated identical photon pair. The state is characterized by 92.9±0.9% visibility Hong-Ou-Mandel interference. The photon flux reaches ∼1.4×10(7)  pairs nm-1 mW-1. The whole chip is designed to contain nine similar units to produce identical photon pairs spanning the telecom C and L band by the flexible engineering of nonlinearity. Our work presents a scenario for on-chip engineering of different photon sources and paves the way to fully integrated quantum technologies.

Mode division multiplexing in a polymer-loaded plasmonic planar waveguide

A mode division multiplexer (MDM) based on in-plane diffractions is experimentally demonstrated in a polymer-loaded plasmonic planar waveguide. Three guided modes (TM₁, TE₁, and TM₂) were well demultiplexed by a focusing design with a focal length of about 40 μm, which are clearly distinguished by the polarization control. The experimental results well reproduced the theoretical design and calculation. Moreover, the demultiplexed focal spots directly reflect the different modes, by which a mode diagram of the dielectric-loaded planar waveguide was vividly mapped out by varying the polymer layer thickness. In this regard, the proposed device may not only serve as a MDM for the integrated optics but can also provide a new strategy in analyzing the guided modes.

Concurrent optical parametric down-conversion in χ(2) nonlinear photonic crystals

We experimentally investigated concurrent parametric downconversion processes in a two-dimensional hexagonally poled lithium tantalate crystal. The substantial enhancement of parametric gain was observed when concurrent processes shared a common parametric beam. Both degenerate and nondegenerate concurrent parametric downconversion processes were studied. Analyses of the spatial forms and output angles showed a strong dependence on the working temperature, during which a well-defined beamlike parametric output was observed. Our results will stimulate the design for coherent high-gain generation of multiple parametric beams and also shed light on the compact engineering of path-entanglement with specific spatial forms based on concurrent spontaneous parametric downconversion processes.

Refractive index sensor based on the leaky radiation of a microfiber

In this work we present a refractive index sensor based on the leaky radiation of a microfiber. The 5.3um diameter microfiber is fabricated by drawing a commercial optical fiber. When the microfiber is immersed into a liquid with larger refractive index than the effective index of fiber mode, the light will leak out through the leaky radiation process. The variation of refractive index of liquid can be monitored by measuring radiation angle of light. The refractive index sensitivity can be over 400 degree/RIU in theory. In the experiment, the variation value 0.001 of refractive index of liquid around this microfiber can be detected through this technique. This work provides a simple and sensitive method for refractive index sensing application.

Diode-pumped 1988-nm Tm:YAP laser mode-locked by intracavity second-harmonic generation in periodically poled LiNbO₃

We report a diode-pumped intracavity second-harmonic generation mode-locked solid-state Tm:YAP laser operating at 1988 nm using a periodically poled congruent LiNbO3 as the nonlinear crystal. The threshold of continuous wave mode locking is 11.6 W. The maximum output power is 1.67 W, while the shortest pulse obtained is 4.7 ps at a repetition rate of 97.09 MHz.

Compact engineering of path-entangled sources from a monolithic quadratic nonlinear photonic crystal

An integrated realization of photonic entangled states becomes an inevitable tendency toward integrated quantum optics. Here we report the compact engineering of steerable photonic path-entangled states from a monolithic quadratic nonlinear photonic crystal. The crystal acts as a coherent beam splitter to distribute photons into designed spatial modes, producing the heralded single-photon and appealing beamlike two-photon path entanglement. We characterize the path entanglement by implementing quantum spatial beating experiments. Such a multifunctional entangled source can be further extended to the high-dimensional fashion and multiphoton level, which paves a desirable way to engineering miniaturized quantum light sources.

Quasi-phase-matched second-harmonic Talbot self-imaging in a 2D periodically-poled LiTaO3 crystal

We demonstrate the improved second-harmonic Talbot self-imaging through the quasi-phase-matching technique in a 2D periodically-poled LiTaO(3) crystal. The domain structure not only composes a nonlinear optical grating which is necessary to realize nonlinear Talbot self-imaging, but also provides reciprocal vectors to satisfy the phase-matching condition for second-harmonic generation. Our experimental results show that quasi-phase-matching can improve the intensity of the second-harmonic Talbot self-imaging by a factor of 21.

High-performance cavity-phase matching by pump reflection

Since cavity-phase matching has been experimentally realized, the efficiency is limited to 20%. In this Letter, we successfully achieved a conversion efficiency as high as 41% with a slope efficiency of 48.5% using cavity-phase matching, by reflecting the pump beam at the end surface of the KTiOPO(4) crystal. The high performance of the device makes it a promising candidate to substitute for quasi-phase-matching material.

Converting surface plasmon to spatial Airy beam by graded grating on metal surface

A well-developed phase modulation method is utilized to design a nanogroove grating for a desired diffraction process, which gives rise to the conversion of a surface plasmon wave to an Airy-like radiation beam. Experiments and simulations revealed the unique characteristics of the generated Airy-like beam, such as nonspreading, self-bending, and self-healing. Our result confirms the validation of the diffraction strategy for beam engineering in conversions and possibly indicates wider applications in broader areas.

Heralded generation of multipartite entanglement for one photon by using a single two-dimensional nonlinear photonic crystal

We propose a compact scheme for the heralded generation of single-photon multipartite entanglement by using a single two-dimensional nonlinear photonic crystal. Studies have shown that by appropriate structure design, the single-photon entanglement shared among three spatially distinct optical modes can be generated through three concurrent spontaneous parametric down-conversion processes by using the other photon in an identical spatial mode as a trigger. Furthermore, we analyze the entanglement of such heralded single-photon tripartite W-type state theoretically. This method can be expanded for the heralded single-photon N-partite entanglement generation. This compact and stable quantum light source may act as a key ingredient in quantum information science.

Collimated plasmon beam: nondiffracting versus linearly focused

We worked out a new group of collimated plasmon beams by the means of in-plane diffraction with symmetric phase modulation. As the phase type changes from 1.8 to 1.0, the beam undergoes an interesting evolution from focusing to a straight line. Upon this, an intuitive diagram was proposed to elucidate the beam nature and answer the question of whether they are nondiffracting or linear focusing. Based on this diagram, we further achieved a highly designable scheme to modulate the beam intensity (e.g., "lossless" plasmon). Our finding holds remarkable generality and flexibility in beam engineering and would inspire more intriguing photonic designs.

Steering plasmon beam from a point source

We extend the phase modulation method by in-plane diffractions from plane wave incidence to point source of surface plasmon polariton (SPP). A well-defined SPP focus is successfully realized from a point source under the diffraction by a carefully designed nanohole array, which is easy to layout in the future integrated optical circuits. With this method, the SPP Airy beam and finite plane wave are demonstrated as well, proving a general applicability of this modulation method. The proposed method and realized functions are expected of benefits for the future integration optics.

Generation of polarization-entangled photon pairs via concurrent spontaneous parametric downconversions in a single χ(2) nonlinear photonic crystal

We propose a scheme for generating polarization-entangled photon pairs using a χ((2)) nonlinear photonic crystal, which is designed for enabling two concurrent quasi-phase-matched spontaneous parametric downconversion processes. Beamlike photon pairs produced from each process are collinear but noncollinear with the pump. Moreover, the source we design works in a postselection-free way and applies to both degenerate and nondegenerate cases. Combining possible waveguide technologies, our scheme may provide an integrated polarization entanglement source.

Reduction of dinitrotoluene sulfonates in TNT red water using nanoscale zerovalent iron particles

PURPOSE

This research was designed to investigate the feasibility of converting the dinitrotoluene sulfonates (DNTS) in TNT red water into the corresponding aromatic amino compounds using nanoscale zerovalent iron (NZVI).

METHODS

NZVI particles were simultaneously synthesized and stabilized by sodium borohydride reduction in a nondeoxygenated system. The morphology, elemental content, specific surface area, and crystal properties of the NZVI were characterized before and after the reaction by environmental scanning electron microscope; energy dispersive X-ray; Brunauer, Emmett, and Teller; and X-ray diffraction, respectively. The reduction process was conducted at pH = 6.3 at ambient temperature. The efficiency of the NZVI-mediated DNTS reduction process was monitored by HPLC, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy analyses.

RESULTS

The properties of the NZVI particles prepared were found to be similar to those obtained through oxygen-free preparation and inert stabilization processes. Both 2,4-DNT-3-sulfonate (2,220 mg L(-1)) and 2,4-DNT-5-sulfonate (3,270 mg L(-1)) in TNT red water underwent a pseudo-first-order transformation when mixed with NZVI at room temperature and near-neutral pH. Their observed rate constants were 0.11 and 0.30 min(-1), respectively. Within 1 h of processing, more than 99% of DNTS was converted by NZVI-mediated reduction into the corresponding diaminotoluene sulfonates.

CONCLUSIONS

NZVI can be simultaneously prepared and stabilized in a nondeoxygenated system. NZVI reduction is a highly efficient method for the conversion of DNTS into the corresponding diaminotoluene sulfonates under near-neutral pH conditions. Therefore, NZVI reduction may be useful in the treatment of TNT red water and subsequent recovery of diaminotoluene from explosive wastewater.

Transformation bending device emulated by graded-index waveguide

We demonstrate that a transformation device can be emulated using a gradient-index waveguide. The effective index of the waveguide is spatially varied by tailoring a gradient thickness dielectric waveguide. Based on this technology, we demonstrate a transformation device guiding visible light around a sharp corner, with low scattering loss and reflection loss. The experimental results are in good agreement with the numerical results.

Electrically generated unidirectional surface plasmon source

We experimentally demonstrated an electrically excited surface plasmon source, which was fulfilled in a silver coated light emitting diode (LED) with well-designed gratings. With a DC current supply, surface plasmon polariton (SPP) waves were generated directly from the illuminations of the LED via the grating coupler. By adjusting the grating to a tilted one, a unidirectional SPP beam was successfully attained with a high extinction ratio (ER~10) and an improved launching efficiency. Detailed analyses show that this electrically generated unidirectional SPP has a considerable long propagation distance (~14 μm), allowing for further manipulations in plasmonic integrations and sensors.

Hong-Ou-Mandel interference mediated by the magnetic plasmon waves in a three-dimensional optical metamaterial

We studied the quantum properties of magnetic plasmon waves in a three-dimensional coupled metamaterial. A Hong-Ou-Mandel dip of two-photon interference with a visibility of 86 ± 6.0% was explicitly observed, when the sample was inserted into one of the two arms of the interferometer. This meant that the quantum interference property survived in such a magnetic plasmon wave-mediated transmission process, thus testifying the magnetic plasmon waves owned a quantum nature. A full quantum model was utilized to describe our experimental results. The results showed that the metamaterials could not only steer the classical light but also the non-classical light and they might have potential application in the future quantum information.

Fractional second-harmonic Talbot effect

We demonstrate the fractional second-harmonic (SH) Talbot effect in a hexagonally poled LiTaO3 crystal. We carefully record the SH Talbot images at 1/2, 1/3, and 1/4 Talbot lengths, which are well matched with the simulated images by using the modified Rayleigh-Sommerfeld diffraction formula. A simplified model with a hexagonal array is adopted in the simulations. Also, we use a modified reciprocal vector theory to analytically explain the evolution of the SH array at fractional Talbot lengths. Our results show that the images are sensitive to the duty circle and the background of the array.

Coherent magnetic plasmon modes in a contacting gold nano-sphere chain on a gold slab

A coupled magnetic resonator waveguide, composed of a contacting gold nanosphere chain on a gold slab, is proposed and investigated. A broadband coherent magnetic plasmon mode can be excited in this one dimensional nanostructure. By employing the Lagrangian formalism and the Fourier transform method, the dispersion properties of the wave vector and group velocity of the magnetic plasmon mode are investigated. Small group velocity can be obtained from this system which can be applied as subwavelength slow wave waveguides.

Plasmonic Airy beam generated by in-plane diffraction

We report an experimental realization of a plasmonic Airy beam, which is generated thoroughly on a silver surface. With a carefully designed nanoarray structure, such Airy beams come into being from an in-plane propagating surface plasmon polariton wave, exhibiting nonspreading, self-bending, and self-healing properties. Besides, a new phase-tuning method based on nonperfectly matched diffraction processes is proposed to generate and modulate the beam almost at will. This unique plasmonic Airy beam as well as the generation method would significantly promote the evolutions in in-plane surface plasmon polariton manipulations and indicate potential applications in lab-on-chip photonic integrations.

Efficient second-harmonic generation in nonlinear plasmonic waveguide

We theoretically studied a nonlinear optical process in a hybrid plasmonic waveguide composed of a nonlinear dielectric waveguide and a metal film with a separation of a thin air gap. Owing to the hybridization effect of guided mode and surface plasmon polariton mode, this particular waveguide is able to confine the optical-field in a deep subwavelength scale together with low propagation loss. Based on this, efficient second-harmonic generations (SHG) were revealed at the fundamental wavelength of λ=1.55 μm with good field confinement. The SHG efficiency, as well as the coupling coefficient and mode area, were analyzed and discussed in detail with respect to the structural parameters.

Efficiency-enhanced optical parametric down conversion for mid-infrared generation on a tandem periodically poled MgO-doped stoichiometric lithium tantalate chip

We report an efficiency-enhanced mid-infrared generation via optical parametric down conversion. A tandem periodically-poled MgO-doped stoichiometric lithium tantalate crystal is used to realize on-chip generation and amplification of mid-infrared radiation inside an optical parametric oscillator cavity. We achieved 21.2% conversion efficiency (24% slope efficiency), which is among the highest efficiencies for the pump-to-mid-infrared conversion, with 1064 nm Nd class laser pump. The maximum average output power at 3.87 μm reached 635 mW with a 3.0 W pump.

Generation of a twin beam at the cesium line and telecom wavelength by cavity phase matching

Cavity phase matching has been recently demonstrated as a phase-matching method for efficient nonlinear frequency conversion in a microcavity. Here we extend it to the Type I configuration using a sub-coherent-length optical parametric oscillator consisting of an MgO-doped lithium niobate crystal sheet. It generates a tunable single-longitudinal-mode twin beam, which covers the cesium D2 line of 852.1 nm and the extended band of optical communication. This microcavity is capable of peak output power of 58 kW with a maximum conversion efficiency of 18.5%. Broad applications in the areas of light-atom interaction, spectroscopy, optical telecommunication, and quantum optics can be expected.

Directly produced three-color entanglement by quasi-phase-matched third-harmonic generation

A new scheme is presented to directly produce fundamental, second-, and third-harmonic three-color continuous-variable (CV) entangled beams by cascaded quasi-phase-matched third-harmonic generation (THG) in an optical cavity. THG can be achieved with high efficiency through a coupled sum-frequency process between the second-harmonic and the fundamental fields. It is demonstrated that the three beams (fundamental, second-, and third-harmonic fields) are entangled with each other according to the CV entanglement criterion. In this scheme, only one crystal and one pump field can generate three-color CV entangled beams separated by an octave in frequency through quasi-phase-matched cascaded nonlinear process, which may be very useful for the applications in quantum communication and computation networks.

Diode-pumped passively mode-locked Nd:YVO4 laser at 1342 nm with periodically poled LiNbO3

In this Letter, we demonstrate a nonlinear-mirror (NLM) mode-locked diode-pumped solid-state Nd:YVO4 laser operating at 1342 nm, in which the NLM comprises a periodically poled LiNbO3 crystal and a dichroic mirror. The self-starting threshold for cw mode locking is 1.5 W, which is significantly lower than that of saturable absorber mode locking. An average power of 1.52 W at 1342 nm is obtained under diode pump power of 10 W at 808 nm, with the slope efficiency being up to 16.8%. The pulse width and the repetition rate of the mode-locked laser output are about 9.5 ps and 101 MHz, respectively.

Cavity phase matching via an optical parametric oscillator consisting of a dielectric nonlinear crystal sheet

We experimentally demonstrate cavity phase matching for the first time using a sheet optical parametric oscillator which is made of an x-cut KTiOPO(4) crystal sheet. This microcavity presents 220 kW peak power capability for near-frequency-degenerate parametric outputs with up to 23.8% slope efficiency. It also features unique spectral characteristics such as single-longitudinal-mode and narrow linewidth. These attractive properties predict broad applications of such a mini-device, such as terahertz generation, photonic integration, spectroscopy, and quantum information, etc.

Strong light-induced negative optical pressure arising from kinetic energy of conduction electrons in plasmon-type cavities

We found that very strong negative optical pressure can be induced in plasmonic cavities by LC resonance. This interesting effect could be described qualitatively by a Lagrangian model which shows that the negative optical pressure is driven by the internal inductance and the kinetic energy of the conduction electrons. If the metal is replaced by perfect conductors, the optical pressure becomes much smaller and positive.

Surface plasmon polariton enhanced by optical parametric amplification in nonlinear hybrid waveguide

We theoretically studied nonlinear interactions between surface plasmon polariton (SPP) and conventional waveguide mode in nonlinear hybrid waveguide and proposed a possible method to enhance SPP wave via optical parametric amplification (OPA). The phase matching condition of this OPA process is fulfilled by carefully tailoring the dispersions of SPP and guided mode. The influences of incident intensity and phase of guided wave on the OPA process are comprehensively analyzed. It is found that not only a strong enhancement of SPP but also modulations on this enhancement can be achieved. This result indicates potential applications in nonlinear optical integration and modulations.

Manipulating optical polarization by stereo plasmonic structure

We theoretically study a particular plasmonic structure with stereo nanoholes array in metallic film, which has remarkable abilities to manipulate the optical polarizations at optical frequencies. The main property is that any linear polarization states including a complete 90° optical rotation can be obtained in transmission by proper structural design in combination of enhanced transmission efficiency. Together with the polarization change, surface plasmon propagation bounded on the surface of transmission side also can be modulated. Furthermore, an analytical Coupled Mode Method (CMM) is developed by introducing a frequency dependent coupling coefficient to describe such optical rotation property in stereo plasmonic systems.

Polarization-free second-order nonlinear frequency conversion using the optical superlattice

We propose a universal and practical scheme to realize polarization-free second-order nonlinear frequency-conversion processes, including sum-frequency generation, difference-frequency generation, and optical parametric amplification. This scheme is based on the optical superlattice with a noncritical phase-matching condition, which is suitable for optical integration. A chirped dual-period structure is proposed to ensure the efficiency and stability of the conversions.

Electric and magnetic excitation of coherent magnetic plasmon waves in a one-dimensional meta-chain

A one-dimensional diatomic meta-chain with equal-size holes and different-length slits is designed. Broadband coherent magnetic plasmon waves (MPW) are formed in such a system, excited by both the electric resonance in the slits and the magnetic resonance in the holes in a wide range of incidence angles (0°-40°) and broad frequency bands (200-230 THz). The dispersion properties of the MPW measured in our experiments agree with the theoretical calculation based on the Lagrange model. The coherent MPWs reported in this paper may have applications in subwavelength integrated nanocircuits.

Chirped-quasi-periodic structure for quasi-phase-matching

We propose in this paper a chirped-quasi-periodic structure using the projection method. This type of new structure combines the advantages of chirped and quasi-periodic structures, and can be used for both multiple quasi-phase-matching and multiple bandwidths control. Numerical simulation of second-harmonic generation performance is in good agreement with the Fourier spectrum of the structure.

Single-pass sum-frequency-generation of 589-nm yellow light based on dual-wavelength Nd:YAG laser with periodically-poled LiTaO(3) crystal

We demonstrate a compact all-solid-state yellow laser source based on Q-switched dual-wavelength Nd:YAG laser and periodically-poled LiTaO(3) crystal. 589-nm yellow light was generated by single-pass sum-frequency generation of the fundamental IR waves at 1064 and 1319 nm. The maximum output power of yellow light was 506 mW and the corresponding conversion efficiency was approximately 5.5% [W(-1)cm(-1)].

Nonlinear Talbot effect

We propose and experimentally demonstrate the nonlinear Talbot effect from nonlinear photonic crystals. The nonlinear Talbot effect results from self-imaging of the generated periodic intensity pattern at the output surface of the crystal. To illustrate the effect, we experimentally observed second-harmonic Talbot self-imaging from 1D and 2D periodically poled LiTaO(3) crystals. Both integer and fractional nonlinear Talbot effects were investigated. The observation not only conceptually extends the conventional Talbot effect, but also opens the door for a variety of new applications in imaging technologies.