High-sensitivity and high-speed measurements of ultrashort pulses as short as 74 fs at 1.9 µm using a GRENOUILLE device

Ultrashort laser pulse sources in the wavelength range of 1.8 to 2 µm have many potential applications including medicine, materials processing, and sensing. In the use of such lasers, a crucial task is to measure their pulse's temporal intensity and phase. Such measurement devices are most useful when they are simple to build and operate and also have high speed and high sensitivity. The GRENOUILLE measurement device with few components, no moving parts, sensitivity of hundreds of picojoules, and measurement speed of hundreds of milliseconds, is commonly used to solve this problem at other wavelengths. In this paper, the measurement of ultrashort pulses by a GRENOUILLE device, developed using a silicon matrix sensor, for pulses in the wavelength range of 1.8 to 2 µm has been demonstrated. It is shown that ultrashort pulses with durations of 74 to 900 fs and a maximum spectral FWHM of 85 nm can be measured with this device. The recently developed ultra-reliable RANA approach was used for pulse retrieval from the measured traces. The device's performance was validated by comparing its measurements with those obtained by the robust FROG technique.

P1697 A rare case: primary cardiac sarcoma in the left and right atrium presenting with dispnea due to mitral valvular obstruction

Introduction Primary cardiac tumors are extremely rare; the incidence is approximately 0.001% to 0.03%. Malignant tumors account for 25% of primary cardiac tumors, and among those, sarcomas are the most prevalent. We report a case of primary cardiac sarcoma presenting with dyspnea due to mitral valvuler obstruction.

Case Report A 41-year-old woman was admitted to the hospital with dyspnea for 8 months without any obvious causes. She was healthy previous and without family history. Physical examination was normal. Thorax computed tomography (CT) scan was performed with the doubt of pulmonary disease. A 1x1 cm hypodense nodule was detected in superior segment of the right lower lobe lung. Positron emission tomography-computed tomography (PET-CT) revealed a 1*1 cm nodule in the lung. And also increased 18F-fluorodeoxyglucose uptake was observed in the left scapula, left iliac wing and right 4th rib, likely due to metastasis. Biopsy from the lesion of iliac wing was performed. Pathologic examination was primarily compatible with the malign mesenchymal tumor and sarcoma infiltration; but malignant epithelial tumor and metastasis of carcinoma could not be ruled out. Magnetic resonance imaging of the lung was performed to find the origin of the metastatic tumor. A 8,6 x 5,3 x 5,1 cm mass filling the right and left atria was detected.It was extending from the right atrium to the superior vena cava and also from the left atrium to the right inferior and superior pulmonary venules. The image of mass was compatible with sarcoma. Transthoracic echocardiography was performed. A mass in the left and right atrium was detected. It was filling the left atrium. Due to the mass, the maximum mitral gradient was 21 mm Hg and the mean mitral gradient was 10 mm Hg, as if there was mitral stenosis.Systolic pulmonary artery pressure was 40 mmHg. Mild mitral insufficiency was detected. The patient was evaluated with the department of oncology and cardiovascular surgery. It was decided that the mass was inoperable. So transesophageal echocardiography was not performed. It was thought that, the mass was primary cardiac sarcoma, pulmonary nodule and bone lesions were metastasis of this primary cardiac sarcoma. So chemotherapy protocol (ifosfamide,adriamycin,mesna) was started.

Conclusion Cardiac tumors have many clinical presentations. Early stages of the disease are often asymptomatic. In advanced stages, patients present with symptoms of the classic triad (intracardiac obstruction, systemic embolization, constitutional symptoms) Symptoms are often non-spesific; so diagnostic suspicion is very important. Although cardiac sarcoma therapy includes complete surgical excision, followed by radiotherapy and chemotherapy, prognosis is still poor. Surgery can offer dramatic palliation of symptoms in cases of valvular obstruction. In conclusion, it remains clear that early diagnosis and treatment are extremely important because of their prognostic and therapeutic value.

Abstract P1697 Figure.

P1703 Cardiac metastasis of germ cell tumor "like beads" in the right heart chambers and also left atrium

Introduction

Testis tumors constitute 1-2% of all malignant tumors in men. But it is the most common solid tumor in men between 15-35 years of age. Germ cell tumors constitute for almost 90% of all testis tumors. Intracardiac metastasis of testicular carcinomas is rare. We now report a case of a testicular germ cell tumor with right atrial metastasis.

Case report

A 30-year-old male patient was diagnosed with B-cell ALL.Chemotherapy and radiotherapy were completed in 2016. In January 2017, the patient applied to the hospital with pain in the right testicle.A mass detected and orchiectomy was performed.Pathologic examination revealed mixed germ cell tumor and B-cell ALL infiltration.Chemotherapy was started. The patient was admitted to our hospital with fever, in March 2018.Antibiotics were started but fever contuniued.Transthoracic echocardiography showed a large,hypoechogen,mobile mass in the right atrium.Then transesophageal echocardiography revealed a 2x3,3 cm mobile mass within the right atrium that prolapsed through the tricuspid valve into the right ventricle in diastole.We could not distinguish if it is a vegetation or a metastatic mass. The patient underwent cardiac surgery.Pathologic examination revealed mixed germ cell tumor metastasis.

After the surgery, the patient was transferred to the intensive care unit because of sepsis. Antibiotics were expanded due to fever. Control transthoracic echocardiography and also transesophageal echocardiography showed a 1,8 x 0,6 cm mobile mass extending from the inferior vena cava into the right atrium and through the patent foramen ovale into the left atrium. One week after the surgery, a mass was detected in the transthoracic echocardiography. But no further examination was done. We thought that the mass may not have been completely removed in the the operation (residual tumor?). The patient was evaluated with the department of oncology and cardiovascular surgery. It was decided that reoperation would be very risky.

Conclusion

Metastatic tumors of the heart are seen more frequently than primary tumors. Although intracardiac metastasis of testicular germ cell tumors are rare (less than %1), it has been related to short survival. They may lead to the congestive heart failure, paradoxical systemic emboli and vena cava superior syndrome. Most cases in the literature are associated with right atrial mass. But in our case, the mass was extending from the inferior vena cava into the right atrium and through the patent foramen ovale into the left atrium. We wanted to share our experience and also wanted to discuss the treatment modality for similar patients.

Abstract P1703 Figure.

Is There a Long-Term Risk for Donors With Heterozygous MEFV Mutation After Kidney Donation?

BACKGROUND

Familial Mediterranean fever (FMF) is an autosomal-recessive autoinflammatory disorder manifested severely by systemic amyloidosis. It has been hypothesized that heterozygous carriers may also have susceptibility to certain symptoms or even diseases. Because the living kidney donors of patients with FMF are generally relatives of the kidney recipients, there is a high possibility that the donors will have a heterozygous mutation of the FMF gene. The goal of this study was to investigate the long-term kidney function of donors who are carriers of the Mediterranean fever (MEFV) gene.

METHODS

The medium- to long-term outcomes of 12 asymptomatic donors were compared with MEFV gene carriers and 24 non-FMF recipients' donors.

RESULTS

Heterozygous carriers and the control group were similar with respect to age, sex, and follow-up period. The preoperative estimated glomerular filtration rate and 24-hour urine proteinuria levels were similar in the MEFV carrier and control groups. Four years after the donation, both groups had similar estimated glomerular filtration rates, but the change in 24-hour urine protein was statistically higher in the MEFV carrier group, and no significant change was observed in the control group (P = .004). At the end of the follow-up period, neither overt proteinuria nor kidney failure was seen in either group.

CONCLUSIONS

This study showed that the medium- to long-term results of the kidney donors who are carriers of the MEFV gene seem to be safe. However, there was more of a tendency for an increase in proteinuria in the MEFV gene carriers compared with control subjects, which necessitated further long-term care for these donors.

Propagation characteristics of Bessel beams generated by continuous, incoherent light sources

We investigate the propagation behavior of Bessel beams generated by incoherent, continuous light sources. We perform experiments with narrowband and broadband light emitting diodes, and, for comparison, with a laser diode. We observe that the formation of Bessel beams is affected minimally by temporal coherence, while spatial coherence determines the longitudinal evolution of the beam profile. With spatially incoherent beams, the fringe contrast is comparable to the coherent case at the beginning of the Bessel zone, while it completely fades away by propagation, turning into a cylindrical light pipe. Our results show that beam shaping methods can be extended to cases of limited spatial coherence, paving the way for potential new uses and applications of such sources.

Femtosecond laser etching of dental enamel for bracket bonding

The aim is to investigate femtosecond laser ablation as an alternative method for enamel etching used before bonding orthodontic brackets. A focused laser beam is scanned over enamel within the area of bonding in a saw tooth pattern with a varying number of lines. After patterning, ceramic brackets are bonded and bonding quality of the proposed technique is measured by a universal testing machine. The results are compared to the conventional acid etching method. Results show that bonding strength is a function of laser average power and the density of the ablated lines. Intrapulpal temperature changes are also recorded and observed minimal effects are observed. Enamel surface of the samples is investigated microscopically and no signs of damage or cracking are observed. In conclusion, femtosecond laser exposure on enamel surface yields controllable patterns that provide efficient bonding strength with less removal of dental tissue than conventional acid-etching technique.

Photosensitivity control of an isotropic medium through polarization of light pulses with tilted intensity front

We present the first experimental evidence of anisotropic photosensitivity of an isotropic homogeneous medium under uniform illumination. Our experiments reveal fundamentally new type of light induced anisotropy originated from the hidden asymmetry of pulsed light beam with a finite tilt of intensity front. We anticipate that the observed phenomenon, which enables employing mutual orientation of a light polarization plane and pulse front tilt to control interaction of matter with ultrashort light pulses, will open new opportunities in material processing.

Direct generation of 81 nJ pulses and external compression to a subpicosecond regime with a 4.9 MHz chirped-pulse multipass-cavity Cr⁴⁺:forsterite oscillator

We report direct generation of 81 nJ chirped pulses from a room-temperature, Kerr lens mode-locked Cr⁴⁺:forsterite oscillator operating at 1258 nm. To increase the pulse energy, the pulse repetition rate of the short x-type resonator was lowered from 143 to 4.9 MHz by the addition of a q-preserving multipass cavity, which provided an additional effective optical path length of 59.4 m. The duration of the chirped pulses was around 5.5 ps with a spectral width of 21 nm. The pulses were externally compressed to 607 fs by using a diffraction grating pair. To our knowledge, this is the highest reported pulse energy directly generated from a room-temperature mode-locked Cr⁴⁺:forsterite laser.

Optical element for generation of accelerating Airy beams

We demonstrate an optical element for generation of accelerating Airy beams. The element is conveniently constructed by combination of positive and negative cylindrical lenses of matching radii of curvature. With proper choice of lens curvatures, the resulting surface profile closely follows a cubic polynomial. Passing a gaussian beam through this element and performing optical Fourier transform yields beam profiles close to the Airy function. Our experiments demonstrate parabolic propagation, or acceleration, of the resulting focal spots.

Revival of femtosecond laser plasma filaments in air by a nanosecond laser

Short lived plasma channels generated through filamentation of femtosecond laser pulses in air can be revived after several milliseconds by a delayed nanosecond pulse. Electrons initially ionized from oxygen molecules and subsequently captured by neutral oxygen molecules provide the long-lived reservoir of low affinity allowing this process. A Bessel-like nanosecond-duration laser beam can easily detach these weakly bound electrons and multiply them in an avalanche process. We have experimentally demonstrated such revivals over a channel length of 50 cm by focusing the nanosecond laser with an axicon.

Compression of ultrashort laser pulses in planar hollow waveguides: a stability analysis

We investigate compression of ultrashort laser pulses by nonlinear propagation in gas-filled planar hollow waveguides, using (3+1)- dimensional numerical simulations. In this geometry, the laser beam is guided with a fixed size in one transverse dimension, generating significant spectral broadening, while it propagates freely in the other, allowing for energy up-scalability. In this respect the concept outperforms compression techniques based on hollow core fibers or filamentation. Small-scale self-focusing is a crucial consideration, which introduces mode deterioration and finally break-up in multiple filaments. The simulation results, which match well with initial experiments, provide important guidelines for scaling the few-cycle pulse generation to higher energies. Pulse compression down to few-cycle duration with energies up to 100 mJ levels should be possible.

High-energy ultrashort laser pulse compression in hollow planar waveguides

We demonstrate compression of high-energy ultrashort laser pulses by nonlinear propagation inside gas-filled planar hollow waveguides. We adjust the input beam size along the nonguided dimension of the planar waveguide to restrain the intensity below photoionization, while the relatively long range guided propagation yields significant self-phase modulation and spectral broadening. We compare the compression in different noble gases and obtain 13.6 fs duration with output pulse energy of 8.1 mJ in argon and 11.5 fs duration with 7.6 mJ energy in krypton. The broadened spectra at the output of the waveguide are uniform over more than 70% of the total pulse energy. Shorter duration could be obtained at the expense of the introduction of spatial structure in the beam (and eventual formation of filaments) resulting from small-scale self-focusing in the nonguided direction.

Spectrogram representation of pulse self compression by filamentation

We report on numerical simulations and experiments of pulse self-compression by filamentation. Spectral and temporal evolution during ultrashort-pulse laser filamentation can be intuitively represented using spectrograms, which display spectra at different time delays of a gate pulse. This representation makes evident the features of self-compression by filamentation, namely spectral broadening and pulse shortening. In addition, it allows for an analysis of the spectral phase during the nonlinear propagation. In our simulations we observe occurrence of negative chirp over a few cm before the shortest pulse is obtained during filamentation; this provides an important basis for the understanding of the mechanisms leading to self-compressed filaments. We attribute the negative chirp to spatio-temporal reshaping due to the competition between self-phase modulation and group velocity dispersion. We show that the plasma induced dispersion plays a minor role in establishing the negative chirp.

A simple method for determination of nonlinear propagation regimes in gases

A simple method to evaluate the nonlinear propagation regimes in gases is demonstrated. The principle is to focus ultrashort laser pulses into a gas cell, vary the input pulse power and measure the transmission through a pinhole placed at the output. The resulting transmission curve yields an intuitive signature of various nonlinear propagation regimes. Going from low powers to higher, one first observes a brief decrease in the transmission due to nonlinear moving focus. Then, a sharp rise occurs, indicating the starting of the filamentation process. When the power increases further, the transmission saturates and eventually decreases due to the beginning of multi-filamentation. As a result, this method gives a quick and sensitive measurement of pulse energies required to have single and multiple filaments.

Terahertz radiation source in air based on bifilamentation of femtosecond laser pulses

A new terahertz (THz) source in air based on the bifilamentation of femtosecond laser pulses is reported. This THz radiation is 1 order of magnitude more intense than the transition-Cherenkov THz emission from femtosecond laser filaments reported recently and shows different angular and polarization properties. We attribute it to the emission from a bimodal transmission line created by two plasma filaments.

Experimentally simple, extremely broadband transient-grating frequency-resolved-opticalgating arrangement

We demonstrate a simple, essentially alignment-free Transient-Grating Frequency-Resolved-Optical-Gating arrangement using a simple input mask that separates the input beam into three beams and a Fresnel biprism that crosses and delays them. It naturally operates single shot and has no moving parts. It is also extremely broadband and hence should be ideal for measuring pulses from optical parametric amplifiers.

Describing first-order spatio-temporal distortions in ultrashort pulses using normalized parameters

We develop a first-order description of spatio-temporal distortions in ultrashort pulses using normalized parameters that allow for a direct assessment of their severity, and we give intuitive pictures of pulses with different amounts of the various distortions. Also, we provide an experimental example of the use of these parameters in the case of spatial chirp monitored in real-time during the alignment of an amplified laser system.

Crossed-beam spectral interferometry: a simple, high-spectral-resolution method for completely characterizing complex ultrashort pulses in real time

We present a high-spectral-resolution and experimentally simple version of spectral interferometry using optical fibers and crossed beams, which we call SEA TADPOLE. Rather than using collinear unknown and reference pulses separated in time to yield spectral fringes-and reduced spectral resolution-as in current versions, we use time-coincident pulses crossed at a small angle to generate spatial fringes. This allows the extraction of the spectral phase with the full spectrometer resolution, which allows the measurement of much longer and more complex pulses. In fact, SEA TADPOLE achieves spectral super-resolution, yielding the pulse spectrum with even better resolution. Avoiding collinear beams and using fiber coupling also vastly simplify alignment. We demonstrate SEA TADPOLE by measuring a chirped pulse, a double pulse separated by 14 ps, and a complex pulse comprising two trains of pulses with a time-bandwidth product of ~400.

Extremely simple single-prism ultrashort- pulse compressor

We have designed and demonstrated a very simple and compact ultrashort-pulse compressor using a single prism and a corner-cube. Our design is significantly easier to align and tune compared with previous designs. Angle-tuning the prism wavelength-tunes, and translating the corner cube varies the group-delay dispersion over a wide range. When tuned, the device automatically maintains zero angular dispersion, zero pulse-front tilt, zero spatial chirp, and unity magnification. The device can easily be built so that its output beam remains collinear with the input beam, and when the input beam or pulse compressor moves, the input and output beams remain collinear.

A RAT MODEL OF POLYPROPYLENE GRAFT INFECTION CAUSED BY STAPHYLOCOCCUS EPIDERMIDIS

BACKGROUND

The aim of this study was to constitute a valid graft infection model with Staphylococcus epidermidis in rats.

METHODS

Rats were divided into seven groups. In groups 1 and 2, 2 cm x 2 cm polypropylene grafts were incubated with 10(8) c.f.u./mL slime-positive S. epidermidis at 37 degrees C for 2 and 24 h and were then placed subfascially to the groins of rats. In the third group, naive grafts were placed and 0.5 mL of 3 x 10(7) c.f.u. slime-positive S. epidermidis were injected on the inside of the wounds. Rifampicin (30 mg/kg) in group 4 and teicoplanin (20 mg/kg) in group 5 were applied i.p. to rats with 2-h incubated grafts for prophylaxis. The same prophylactic regimens were given to groups 6 and 7 in which rats were incubated for 24 h. At eighth day, rats were killed and wounds were assessed with macroscopic evaluation and cultures.

RESULTS

No death occurred in any of the groups. In groups 1 and 2, 100% infection rates were achieved. However, graft infection was detected in only two (20%) of the rats in group 3 (P = 0.001). Prophylactic application of teicoplanin or rifampicin decreased the infection rates significantly in the short-incubation groups.

CONCLUSION

Incubation of polypropylene grafts with slime-producing S. epidermidis for 2 and 24 h in the pre-application period achieved the occurrence of a standardized graft infection. Prophylactic use of teicoplanin and rifampicin decreased the infection rates. We propose to use this reproducible and reliable animal model of graft infection in future studies.

The general theory of first-order spatio-temporal distortions of Gaussian pulses and beams

We present a rigorous, but mathematically relatively simple and elegant, theory of first-order spatio-temporal distortions, that is, couplings between spatial (or spatial-frequency) and temporal (or frequency) coordinates, of Gaussian pulses and beams. These distortions include pulse-front tilt, spatial dispersion, angular dispersion, and a less well-known distortion that has been called "time vs. angle." We write pulses in four possible domains, xt, xomega, komega, and kt; and we identify the first-order couplings (distortions) in each domain. In addition to the above four "amplitude" couplings, we identify four new spatio-temporal "phase" couplings: "wave-front rotation," "wave-front-tilt dispersion," "angular temporal chirp," and "angular frequency chirp." While there are eight such couplings in all, only two independent couplings exist and are fundamental in each domain, and we derive simple expressions for each distortion in terms of the others. In addition, because the dimensions and magnitudes of these distortions are unintuitive, we provide normalized, dimensionless definitions for them, which range from -1 to 1. Finally, we discuss the definitions of such quantities as pulse length, bandwidth, angular divergence, and spot size in the presence of spatio-temporal distortions. We show that two separate definitions are required in each case, specifically, "local" and "global" quantities, which can differ significantly in the presence of spatio-temporal distortions.

Pulse-front tilt caused by spatial and temporal chirp

Pulse-front tilt in an ultrashort laser pulse is generally considered to be a direct consequence of, and equivalent to, angular dispersion. We show, however, that, while this is true for certain types of pulse fields, simultaneous temporal chirp and spatial chirp also yield pulse-front tilt, even in the absence of angular dispersion. We verify this effect experimentally using GRENOUILLE.

Extremely simple device for measuring 1.5-microm ultrashort laser pulses

We have demonstrated an experimentally very simple and sensitive GRENOUILLE device for measuring the intensity and phase vs. time and spatio-temporal distortions of 100-fs to few-ps 1.5-microm pulses using the nonlinear-optical crystal Proustite. We show that the dispersive and nonlinear-optical characteristics of Proustite are critical for achieving very simple and reliable measurements of such pulses from fiber lasers and optical parametric amplifiers.

Extremely simple device for measuring 20-fs pulses

We demonstrate an extremely simple frequency-resolved optical-gating device (GRENOUILLE) capable of measuring pulses with spectra wider than 100 nm. Its nearly all-reflective geometry minimizes the material dispersion, allowing accurate measurement of pulses as short as 19 fs.

Measuring several-cycle 1.5-m pulses using frequency-resolved optical gating

We demonstrate frequency-resolved optical gating (FROG) for measuring the full intensity and phase of several-optical-cycle 1.5-m pulses generated from a Kerr-lens mode-locked (KLM) Cr4+:YAG laser. This involves the use of an angle-dithered second-harmonic-generation crystal to achieve the full pulse bandwidth despite the use of a relatively thick nonlinear crystal.

Measuring pulse-front tilt in ultrashort pulses using GRENOUILLE

We show that the spatio-temporal distortion, pulse-front tilt, is naturally, easily, and sensitively measured by the recently demonstrated, extremely simple variation of single-shot second-harmonic generation frequency-resolved optical gating (SHG FROG): GRENOUILLE. While GRENOUILLE traces are ordinarily centered on the zero of delay, a pulse with pulse-front tilt yields a trace whose center is shifted to a nonzero delay that is proportional to the pulse-front tilt. As a result, the trace-center shift reveals both the magnitude and sign of the pulse-front tilt-independent of the temporal pulse intensity and phase. The effects of pulse-front tilt can then easily be removed from the trace and the intensity and phase vs. time also retrieved, yielding a full description of the pulse in space and time.

Measuring spatial chirp in ultrashort pulses using single-shot Frequency-Resolved Optical Gating

We show that the spatio-temporal distortion, spatial chirp, is naturally and easily measured by single-shot versions of second-harmonic generation frequency-resolved optical gating (SHG FROG) (including the extremely simple version, GRENOUILLE);. While SHG FROG traces are ordinarily symmetrical, a pulse with spatial chirp yields a trace with a shear that is approximately twice the pulse spatial chirp. As a result, the trace shear unambiguously reveals both the magnitude and sign of the pulse spatial chirp. The effects of spatial chirp can then be removed from the trace and the intensity and phase vs. time also retrieved, yielding a full description of the spatially chirped pulse in space and time.