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Liu J, Zhang Z. Polymer-Embedding Germanium Nanostrip Waveguide of High Polarization Extinction. Polymers (Basel) 2023; 15:4093. [PMID: 37896336 PMCID: PMC10610098 DOI: 10.3390/polym15204093] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 10/06/2023] [Accepted: 10/08/2023] [Indexed: 10/29/2023] Open
Abstract
Germanium (Ge) nanostrip was embedded in a polymer and studied as a waveguide. The measurements reveal that this new type of semiconductor/polymer heterogeneous waveguide exhibits strong absorption for the TE mode from 1500 nm to 2004 nm, while the propagation loss for the TM mode declines from 20.56 dB/cm at 1500 nm to 4.89 dB/cm at 2004 nm. The transmission characteristics serve as an essential tool for verifying the optical parameters (n-κ, refractive index, and extinction coefficient) of the strip, addressing the ambiguity raised by spectroscopic ellipsometry regarding highly absorbing materials. Furthermore, the observed strong absorption for the TE mode at 2004 nm is well beyond the cut-off wavelength of the crystalline bulk Ge (~1850 nm at room temperature). This redshift is modeled to manifest the narrowing of the Tauc-fitted bandgap due to the grain order effect in the amorphous Ge layer. The accurate measurement of the nanometer-scale light-absorbing strips in a waveguide form is a crucial step toward the accurate design of integrated photonic devices that utilize such components.
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Affiliation(s)
- Jinyuan Liu
- College of Information Science and Electronic Engineering, Zhejiang University, Hangzhou 310027, China;
- Laboratory of Photonic Integration, School of Engineering, Westlake University, Hangzhou 310024, China
| | - Ziyang Zhang
- Laboratory of Photonic Integration, School of Engineering, Westlake University, Hangzhou 310024, China
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2
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Li Q, Xiong X, Yan Z, Cheng G, Xu F, Shen Z, Yi Q, Yu Y, Shen L. High-speed mid-infrared graphene electro-optical modulator based on suspended germanium slot waveguides. Opt Express 2023; 31:29523-29535. [PMID: 37710751 DOI: 10.1364/oe.496269] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2023] [Accepted: 08/05/2023] [Indexed: 09/16/2023]
Abstract
The mid-infrared (MIR) region is attracting increasing interest for on-chip synchronous detection and free-space optical (FSO) communications. For such applications, a high-performance electro-optical modulator is a crucial component. In this regard, we propose and investigate a graphene-based electro-absorption modulator (EAM) and microring modulator (MRM) using the suspended germanium waveguide platform. The modulators are designed for the second atmospheric window (8 to 12 µm). The incorporation of double-layer graphene on the suspended slot waveguide structure allows for the significant enhancement of light-graphene interaction, theoretically achieving a 3-dB bandwidth as high as 78 GHz. The EAM shows a calculated modulation depth of 0.022-0.045 dB/µm for the whole operation wavelength range. The MRM exhibits a calculated extinction ratio as high as 68.9 dB and a modulation efficiency of 0.59 V·cm around 9 µm. These modulators hold promise for constructing high-speed FSO communication and on-chip spectroscopic detection systems in the MIR atmospheric window.
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3
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Georgiev GV, Cao W, Zhang W, Ke L, Thomson DJ, Reed GT, Nedeljkovic M, Mashanovich GZ. Near-IR & Mid-IR Silicon Photonics Modulators. Sensors (Basel) 2022; 22:9620. [PMID: 36559988 PMCID: PMC9783169 DOI: 10.3390/s22249620] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 11/17/2022] [Accepted: 11/30/2022] [Indexed: 06/17/2023]
Abstract
As the silicon photonics field matures and a data-hungry future looms ahead, new technologies are required to keep up pace with the increase in capacity demand. In this paper, we review current developments in the near-IR and mid-IR group IV photonic modulators that show promising performance. We analyse recent trends in optical and electrical co-integration of modulators and drivers enabling modulation data rates of 112 GBaud in the near infrared. We then describe new developments in short wave infrared spectrum modulators such as employing more spectrally efficient PAM-4 coding schemes for modulations up to 40 GBaud. Finally, we review recent results at the mid infrared spectrum and application of the thermo-optic effect for modulation as well as the emergence of new platforms based on germanium to tackle the challenges of modulating light in the long wave infrared spectrum up to 10.7 μm with data rates of 225 MBaud.
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Goldstein J, Lin H, Deckoff-Jones S, Hempel M, Lu AY, Richardson KA, Palacios T, Kong J, Hu J, Englund D. Waveguide-integrated mid-infrared photodetection using graphene on a scalable chalcogenide glass platform. Nat Commun 2022; 13:3915. [PMID: 35798746 DOI: 10.1038/s41467-022-31607-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2022] [Accepted: 06/16/2022] [Indexed: 11/14/2022] Open
Abstract
The development of compact and fieldable mid-infrared (mid-IR) spectroscopy devices represents a critical challenge for distributed sensing with applications from gas leak detection to environmental monitoring. Recent work has focused on mid-IR photonic integrated circuit (PIC) sensing platforms and waveguide-integrated mid-IR light sources and detectors based on semiconductors such as PbTe, black phosphorus and tellurene. However, material bandgaps and reliance on SiO2 substrates limit operation to wavelengths λ ≲ 4 μm. Here we overcome these challenges with a chalcogenide glass-on-CaF2 PIC architecture incorporating split-gate photothermoelectric graphene photodetectors. Our design extends operation to λ = 5.2 μm with a Johnson noise-limited noise-equivalent power of 1.1 nW/Hz1/2, no fall-off in photoresponse up to f = 1 MHz, and a predicted 3-dB bandwidth of f3dB > 1 GHz. This mid-IR PIC platform readily extends to longer wavelengths and opens the door to applications from distributed gas sensing and portable dual comb spectroscopy to weather-resilient free space optical communications. Mid-infrared photonic integrated circuits (PICs) are important for sensing and optical communications, but their operational wavelengths are usually limited below 4 μm. Here, the authors report the realization of photothermoelectric graphene photodetectors incorporated in a chalcogenide glass-on-CaF2 PIC operating at 5.2 μm, showing promising results for gas sensing applications.
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5
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Sánchez-Postigo A, Ortega-Moñux A, Soler Penadés J, Osman A, Nedeljkovic M, Qu Z, Wu Y, Molina-Fernández Í, Cheben P, Mashanovich GZ, Wangüemert-Pérez JG. Suspended germanium waveguides with subwavelength-grating metamaterial cladding for the mid-infrared band. Opt Express 2021; 29:16867-16878. [PMID: 34154239 DOI: 10.1364/oe.422764] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 04/22/2021] [Indexed: 06/13/2023]
Abstract
In recent years, sensing and communication applications have fueled important developments of group-IV photonics in the mid-infrared band. In the long-wave range, most platforms are based on germanium, which is transparent up to ∼15-µm wavelength. However, those platforms are limited by the intrinsic losses of complementary materials or require complex fabrication processes. To overcome these limitations, we propose suspended germanium waveguides with a subwavelength metamaterial lateral cladding that simultaneously provides optical confinement and allows structural suspension. These all-germanium waveguides can be fabricated in one dry and one wet etch step. A propagation loss of 5.3 dB/cm is measured at a wavelength of 7.7 µm. These results open the door for the development of integrated devices that can be fabricated in a simple manner and can potentially cover the mid-infrared band up to ∼15 µm.
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6
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Kozak DA, Tyndall NF, Pruessner MW, Rabinovich WS, Stievater TH. Germanium-on-silicon waveguides for long-wave integrated photonics: ring resonance and thermo-optics. Opt Express 2021; 29:15443-15451. [PMID: 33985244 DOI: 10.1364/oe.420687] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 04/09/2021] [Indexed: 06/12/2023]
Abstract
Germanium-on-silicon (GOS) represents the leading platform for foundry-based long-wave infrared photonic integrated circuits (LWIR PICs), due to its CMOS compatibility and absence of oxides. We describe ring resonance (Q-factors between 2×103 and 1×104) and thermo-optic tunability in germanium-on-silicon waveguides throughout the long-wave-infrared. The ring resonances are characterized by Q-factors and couplings that agree with measurements of propagation loss (as low as 6 dB/cm) and simulations and are enabled by broadband edge coupling (12dB/facet over a 3 dB bandwidth of over 4 microns). We demonstrate the furthest into the infrared that ring resonators have been measured and show the potential of this platform for photonic integration and waveguide spectroscopy at wavelengths from 7 microns to beyond 11 microns.
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Koompai N, Chaisakul P, Limsuwan P, Le Roux X, Vivien L, Marris-Morini D. Design and Simulation Investigation of Si 3N 4 Photonics Circuits for Wideband On-Chip Optical Gas Sensing around 2 µm Optical Wavelength. Sensors (Basel) 2021; 21:s21072513. [PMID: 33916817 PMCID: PMC8038381 DOI: 10.3390/s21072513] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/25/2021] [Accepted: 04/01/2021] [Indexed: 11/16/2022]
Abstract
We theoretically explore the potential of Si3N4 on SiO2 waveguide platform toward a wideband spectroscopic detection around the optical wavelength of 2 μm. The design of Si3N4 on SiO2 waveguide architectures consisting of a Si3N4 slot waveguide for a wideband on-chip spectroscopic sensing around 2 μm, and a Si3N4 multi-mode interferometer (MMI)-based coupler for light coupling from classical strip waveguide into the identified Si3N4 slot waveguides over a wide spectral range are investigated. We found that a Si3N4 on SiO2 slot waveguide structure can be designed for using as optical interaction part over a spectral range of interest, and the MMI structure can be used to enable broadband optical coupling from a strip to the slot waveguide for wideband multi-gas on-chip spectroscopic sensing. Reasons for the operating spectral range of the system are discussed.
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Affiliation(s)
- Natnicha Koompai
- Centre de Nanosciences et de Nanotechnologies, Université Paris Sud, CNRS, Université Paris Saclay, 91120 Palaiseau, France
- Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Papichaya Chaisakul
- Department of Physics, Faculty of Science, Kasetsart University, Bangkok 10900, Thailand
| | - Pichet Limsuwan
- Department of Physics, Faculty of Science, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand
| | - Xavier Le Roux
- Centre de Nanosciences et de Nanotechnologies, Université Paris Sud, CNRS, Université Paris Saclay, 91120 Palaiseau, France
| | - Laurent Vivien
- Centre de Nanosciences et de Nanotechnologies, Université Paris Sud, CNRS, Université Paris Saclay, 91120 Palaiseau, France
| | - Delphine Marris-Morini
- Centre de Nanosciences et de Nanotechnologies, Université Paris Sud, CNRS, Université Paris Saclay, 91120 Palaiseau, France
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Al-Saymari FA, Craig AP, Lu Q, Marshall ARJ, Carrington PJ, Krier A. Mid-infrared resonant cavity light emitting diodes operating at 4.5 µm. Opt Express 2020; 28:23338-23353. [PMID: 32752332 DOI: 10.1364/oe.396928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 07/05/2020] [Indexed: 06/11/2023]
Abstract
We report on a mid-infrared resonant cavity light emitting diode (RCLED) operating at the wavelength of 4.5 µm with a narrow spectral linewidth at room temperature. Compared to a reference LED without a resonant cavity, our RCLED exhibits (85x) higher peak intensity, (13x) higher integrated output power, (16x) narrower spectral linewidth and (7x) superior temperature stability. The device consists of a one-wavelength thick micro-cavity containing an Al0.12In0.88As/InAs0.85Sb0.15 quantum well active region sandwiched between two high contrast AlAs0.08Sb0.92/GaSb distributed Bragg reflector mirrors, grown lattice-matched on GaSb by molecular beam epitaxy. The high spectral brightness, narrow linewidth and superior temperature stability are attractive features, enabling these devices to be used for detection of N2O at 4.5 µm. We show that with only minor adjustments the gases CO2 (4.2 µm) and CO (4.6 µm) are also readily accessible.
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Huang CC, Huang CC. Theoretical analysis of mode conversion by refractive-index perturbation based on a single tilted slot on a silicon waveguide. Opt Express 2020; 28:18986-18999. [PMID: 32672185 DOI: 10.1364/oe.394809] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
We propose a compact mode converter operating at the mid-infrared wavelength of 3.4 µm, comprising an etched parallelogram slot filled with silicon nitride on a silicon-on-calcium fluoride platform. The tilted slot introduces transverse and longitudinal index perturbations on the waveguide eigenmodes, achieving mode conversion in the propagation direction. Differing from previous reports using massive parameter sweep, we provide analytical formulas to determine geometry parameters by considering the modified phase-matching condition and the profiles of coupling coefficient of coupled-mode theory. Rigorous 3D numerical examples demonstrate the transverse electric (TE)0-to-TE1, TE0-to-TE2, TE0-to-TE3, and TE0-to-TE4 converters to achieve conversion efficiencies (inter-modal crosstalk [CT] values) of >92.7% (<-27 dB), >91.7% (<-16 dB), >88.2% (<-13 dB), and >75.8% (<-10 dB), respectively, with a total transmitted power of >93%. Converter device lengths range from 16.84 to 24.61 µm for TE0-to-TE1 to TE0-to-TE4, respectively. Over a broadband wavelength of 100 nm, the conversion efficiency, power transmission, and maximum inter-modal CT are almost >80%, >90%, and <-10 dB, respectively. Also, the fabrication tolerance of the proposed structure is addressed. The proposed model can not only realize arbitrary mode-order conversion but extend to other wavelength bands. To validate the feasibility of our model, the numerical results of our device operating at the wavelength of 1.55 µm are also offered and compared with those of other reports. The proposed idea may pave a new approach to designing mode converters with arbitrary geometries.
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Yoo KM, Midkiff J, Rostamian A, Chung CJ, Dalir H, Chen RT. InGaAs Membrane Waveguide: A Promising Platform for Monolithic Integrated Mid-Infrared Optical Gas Sensor. ACS Sens 2020; 5:861-869. [PMID: 32129061 DOI: 10.1021/acssensors.0c00180] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Mid-infrared (mid-IR) absorption spectroscopy based on integrated photonic circuits has shown great promise in trace-gas sensing applications in which the mid-IR radiation directly interacts with the targeted analyte. In this paper, considering monolithic integrated circuits with quantum cascade lasers (QCLs) and quantum cascade detectors (QCDs), the InGaAs-InP platform is chosen to fabricate passive waveguide gas sensing devices. Fully suspended InGaAs waveguide devices with holey photonic crystal waveguides (HPCWs) and subwavelength grating cladding waveguides (SWWs) are designed and fabricated for mid-infrared sensing at λ = 6.15 μm in the low-index contrast InGaAs-InP platform. We experimentally detect 5 ppm ammonia with a 1 mm long suspended HPCW and separately with a 3 mm long suspended SWW, with propagation losses of 39.1 and 4.1 dB/cm, respectively. Furthermore, based on the Beer-Lambert infrared absorption law and the experimental results of discrete components, we estimated the minimum detectable gas concentration of 84 ppb from a QCL/QCD integrated SWW sensor. To the best of our knowledge, this is the first demonstration of suspended InGaAs membrane waveguides in the InGaAs-InP platform at such a long wavelength with gas sensing results. Also, this result emphasizes the advantage of SWWs to reduce the total transmission loss and the size of the fully integrated device's footprint by virtue of its low propagation loss and TM mode compatibility in comparison to HPCWs. This study enables the possibility of monolithic integration of quantum cascade devices with TM polarized characteristics and passive waveguide sensing devices for on-chip mid-IR absorption spectroscopy.
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Affiliation(s)
- Kyoung Min Yoo
- Department of Electrical and Computer Engineering, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758, United States
| | - Jason Midkiff
- Department of Electrical and Computer Engineering, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758, United States
| | - Ali Rostamian
- Department of Electrical and Computer Engineering, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758, United States
| | - Chi-jui Chung
- Department of Electrical and Computer Engineering, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758, United States
| | - Hamed Dalir
- Omega Optics Inc., 8500 Shoal Creek Blvd., Bldg. 4, Suite 200, Austin, Texas 78757, United States
| | - Ray T. Chen
- Department of Electrical and Computer Engineering, The University of Texas at Austin, 10100 Burnet Rd., Austin, Texas 78758, United States
- Omega Optics Inc., 8500 Shoal Creek Blvd., Bldg. 4, Suite 200, Austin, Texas 78757, United States
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Griskeviciute U, Millar RW, Gallacher K, Valente J, Paul DJ. Ge-on-Si waveguides for sensing in the molecular fingerprint regime. Opt Express 2020; 28:5749-5757. [PMID: 32121790 DOI: 10.1364/oe.382356] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2019] [Accepted: 02/03/2020] [Indexed: 06/10/2023]
Abstract
Low loss, single mode, Ge-on-Si rib waveguides are used to demonstrated optical sensing in the molecular fingerprint region of the mid-infrared spectrum. Sensing is carried out using two spin-coated films, with strong absorption in the mid-infrared. These films are used to calibrate the modal overlap with an analyte, and therefore experimentally demonstrate the potential for Ge-on-Si waveguides for mid-infrared sensing applications. The results are compared to Fourier transform infrared spectroscopy measurements. The advantage of waveguide spectroscopy is demonstrated in terms of the increased optical interaction, and a new multi-path length approach is demonstrated to improve the dynamic range, which is not possible with conventional FTIR or attenuated total reflection (ATR) measurements. These results highlight the potential for Ge-on-Si as an integrated sensing platform for healthcare, pollution monitoring and defence applications.
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12
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Lozeman JJA, Führer P, Olthuis W, Odijk M. Spectroelectrochemistry, the future of visualizing electrode processes by hyphenating electrochemistry with spectroscopic techniques. Analyst 2020; 145:2482-2509. [DOI: 10.1039/c9an02105a] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reviewing the future of electrochemistry combined with infrared, Raman, and nuclear magnetic resonance spectroscopy as well as mass spectrometry.
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Affiliation(s)
- Jasper J. A. Lozeman
- BIOS Lab-on-a-Chip Group
- MESA+ Institute
- University of Twente
- 7522 NB Enschede
- The Netherlands
| | - Pascal Führer
- BIOS Lab-on-a-Chip Group
- MESA+ Institute
- University of Twente
- 7522 NB Enschede
- The Netherlands
| | - Wouter Olthuis
- BIOS Lab-on-a-Chip Group
- MESA+ Institute
- University of Twente
- 7522 NB Enschede
- The Netherlands
| | - Mathieu Odijk
- BIOS Lab-on-a-Chip Group
- MESA+ Institute
- University of Twente
- 7522 NB Enschede
- The Netherlands
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Sánchez-Postigo A, Ortega-Moñux A, Pereira-Martín D, Molina-Fernández Í, Halir R, Cheben P, Penadés JS, Nedeljkovic M, Mashanovich GZ, Wangüemert-Pérez JG. Design of a suspended germanium micro-antenna for efficient fiber-chip coupling in the long-wavelength mid-infrared range. Opt Express 2019; 27:22302-22315. [PMID: 31510526 DOI: 10.1364/oe.27.022302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Accepted: 05/28/2019] [Indexed: 06/10/2023]
Abstract
Recent developments of photonic integrated circuits for the mid-infrared band has opened up a new field of attractive applications for group IV photonics. Grating couplers, formed as diffractive structures on the chip surface, are key components for input and output coupling in integrated photonic platforms. While near-infrared optical fibers exhibit large mode field diameters compared to the wavelength, in the long-wave regime commercially available single-mode optical fibers have mode field diameters of the order of the operating wavelength. Consequently, an efficient fiber-chip surface coupler designed for the long-wave infrared range must radiate the power propagating in the waveguide with a higher radiation strength than a conventional grating coupler in the near-infrared range. In this article, we leverage the short electrical length required for long-wave infrared couplers to design a broadband all-dielectric micro-antenna for a suspended germanium platform at 7.67 µm. The design methodology is inspired by fundamental grating coupler equations, which remain valid even when the micro-antenna has only two or three diffractive elements. A simulated coupling efficiency of ~ 40% is achieved with a 1-dB bandwidth broader than 430 nm, which is almost twice the typical fractional bandwidth of a conventional grating coupler. In addition, the proposed design is markedly tolerant to fiber tilt misalignments of ±10°. This all-dielectric micro-antenna design paves the way for efficient fiber-chip coupling in long-wavelength mid-infrared integrated platforms.
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