- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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The Critical Adiabatic Linear Tapered Waveguide Combined with a Multimode Waveguide Coupler on an SOI Chip
摘要： A multimode waveguide interference (MMI) coupler is combined with a critical linear tapered waveguide on a silicon-on-insulator (SOI) chip. When the TE0 mode is a critical adiabatic mode conversion from a single-mode waveguide to an extreme linear tapered waveguide combined with an MMI, this linear tapered waveguide is achieved to the maximum divergence angle (i.e., the shortest length). The maximum divergence angle is expressed by θ ≤ 2 tan? 1[(0.35Wmmi ? Ws)/(0.172Lmmi)] under a 1 × 1 MMI combined with this critical linear tapered waveguide. The expression formula is demonstrated by three di?erent widths of a 1 × 1 MMI of 4 μm/8 μm/12 μm combined with the critical linear tapered waveguide. So, the maximum divergence angle is obtained at θ ? 16°/14°/8°, with respect to this linear tapered waveguide loss of 0.022 dB/0.172 dB/0.158 dB, and this linear tapper length is reduced by 93.7%/92.9%/87.5% than the divergence angle θ ? 1°. The output power of a 1 × 1 MMI combined with a critical linear tapered waveguide is enhanced at least 1.5 times under 0.95 above condition.
关键词： multimode waveguide interference (MMI) coupler,TE0 mode,linear tapered waveguide,silicon-on-insulator (SOI) chip,adiabatic mode conversion
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - On Chip Sub-Wavelength Grating Fabry-Perot Cavity, toward Integrated Cavity Optomechanics Applications
摘要： Sub-Wavelength Grating (SWG) periodic media are comprised of alternative dielectric layers with a pitch Λ small enough in comparison to the wavelength to supress any diffraction or interference effect. As a good first approximation, SWG media can be considered as uniform and lossless ones, with an averaging effect over the dielectric permittivity [1]. The use of SWG media as core and/or cladding materials of optical waveguides was first proposed and demonstrated in 2010 [2] as a way to realize easy engineering of the refractive guided index of light with simple lithographic patterning. Since then, SWG waveguides have found various applications such as waveguide crossing, multimode interferometers, optical filters, mid-infrared waveguides, or even optical biosensing [3]. We propose to include SWG waveguides within a suspended Fabry-Perot (FP) cavity (see Fig. 1a). The core of the cavity is formed by alternative Silicon and Air SWG layers, while the input and output mirrors are two Direct Bragg Reflectors (DBR). The whole structure is fully suspended through the use of two support arms. We present the theoretical modelization, technological realization and optical characterisations of such a cavity. The design was conducted through both an analytical model that treats SWG media with equivalent refractive indexes, and two dimensional effective index Finite-Difference Time-Domain (FDTD) simulations. Actual devices were realized on 200 mm silicon on insulator (SOI) wafers in our clean room facilities with e-beam patterning of the waveguide level, and characterized via full-scale wafer optical spectrum measurement between 1520 nm and 1580 nm. At time of writing, we measured optical quality factors of 10 000 over 2 μm long cavities. We believe this kind of suspended structure can be used in the field of Cavity Optomechanics, where an optical cavity is coupled to a mechanical resonator [4]. Indeed, because it is fully suspended, we await mechanical resonance to occur, the cavity behaving similarly to a doubly clamped holey cantilever (see Fig. 1c). Apart from the traditional optical phase shift occurring with propagation length variations of the cavity, there should also be a phase shift arising from the SWG nature of the waveguide, whose equivalent refractive index depends on the pitch Λ (and thus length) of the cavity. Due to this additional effect, we expect a strong optomechanical coupling rate.
关键词： Sub-Wavelength Grating,silicon on insulator,optical waveguides,Fabry-Perot cavity,cavity optomechanics
更新于2025-09-12 10:27:22
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Coupling Between Silicon Waveguide and Metal-Dielectric-Metal Plasmonic Waveguide with Lens-Funnel Structure
摘要： Various photonic integrated components have been implemented by ultra-thin silicon-on-insulator (SOI) waveguides; therefore, it is desirable to couple ultra-thin SOI waveguides to plasmonic waveguides. In this paper, we present an ultra-thin SOI waveguide to a metal-dielectric-metal plasmonic waveguide based on a lens-funnel structure consisting of truncated Luneburg lens and metallic parabolic funnel. The lens is implemented by varying the guiding layer thickness. The effect of different parameters of the coupler’s geometry is studied using the finite-difference time-domain method. The 1.13-μm-long coupler improves the average coupling efficiency in the C-band from 66.4 to 82.1%. The numerical simulations indicate that the coupling efficiency is higher than 69% in the entire O, E, S, C, L, and U bands of optical communication.
关键词： Luneburg lens,Silicon-on-insulator,All-dielectric metamaterials,Plasmonic waveguide,Optical coupler,Strip waveguide
更新于2025-09-12 10:27:22
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A Low-Profile and High-Gain Frequency Beam Steering sub-THz Antenna Enabled by Silicon Micromachining
摘要： A very low-profile sub-THz high-gain frequency beam steering antenna, enabled by silicon micromachining, is reported for the first time in this paper. The operation bandwidth of the antenna spans from 220 GHz to 300 GHz providing a simulated field of view of 56?. The design is based on a dielectric filled parallel-plate waveguide (PPW) leaky-wave antenna fed by a pillbox. The pillbox, a two-level PPW structure, has an integrated parabolic reflector to generate a planar wave front. The device is enabled by two extreme aspect ratio, 16 mm x 16 mm large perforated membranes, which are only 30 μm thick, that provide the coupling between the two PPWs and form the LWA. The micromachined low-loss PPW structure results in a measured average radiation efficiency of ?1 dB and a maximum gain of 28.5 dBi with an input reflection coefficient below ?10 dB. The overall frequency beam steering frontend is extremely compact (24 mm x 24 mm x 0.9 mm) and can be directly mounted on a standard WM-864 waveguide flange. The design and fabrication challenges of such high performance antenna in the sub-THz frequency range are described and the measurement results of two fabricated prototypes are reported and discussed.
关键词： beam steering,leaky-wave antennas,silicon on insulator,terahertz radiation,silicon micromachining,quasi-optics,submillimeter-wave antennas
更新于2025-09-11 14:15:04
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Mode Sensitivity Analysis of Subwavelength Grating Slot Waveguides
摘要： In this paper, we investigate the mode sensitivity (Smode) of subwavelength grating slot (SWGS) waveguides. Smode is an important parameter in various waveguide-based photonic circuits such as sensors, modulators, and thermally-controlled devices. It is a measure of the sensitivity of the waveguide effective index towards the refractive index perturbations in the cladding medium. The SWGS waveguide exhibits high mode sensitivity, as it combines sensitivity enhancement features of both slot and subwavelength grating waveguides. Finite-difference time-domain simulations are performed for the analysis, design, and optimization of the hybrid structure. The SWGS waveguide is incorporated into a Mach-Zehnder interferometer and fabricated on a silicon-on-insulator platform for the experimental estimation of Smode. The measured Smode value of 79% is consistent with the theoretical prediction of 83%.
关键词： Subwavelength grating,sensor,silicon-on-insulator,integrated optics,slot waveguide
更新于2025-09-11 14:15:04
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Zero-Birefringence Silicon Waveguides Based on Tilted Subwavelength Metamaterials
摘要： Polarization independent silicon-on-insulator nanowires are highly sought after, due the inherent high birefringence of this material platform. State-of-the-art designs of non-birefringent waveguides include ridge waveguides and square nanowires, which either imply large dimensions, multiple etching steps, low fabrication tolerances or high wavelength dependence. In this work, we overcome all the aforementioned limitations through tilted subwavelength structures which provide anisotropy control of the resulting metamaterial. With a waveguide cross section of only 300 nm x 550 nm (height x width), the zero-birefringence point is obtained for an approximately 48?-tilt of the subwavelength structure. Birefringence of the nominal design deteriorates by only 9.10?3 even in the presence of size deviations of ± 10 nm. Moreover, birefringence is maintained under 6.10?3 in a 100-nm bandwidth around the central wavelength of 1550 nm. This innovative approach is readly adaptable to a wide range of waveguide sizes, while maintaining single-etch-step fabrication.
关键词： polarization independence,silicon-on-insulator (SOI),sub-wavelength grating (SWG),Zero-birefringence waveguides,anisotropy engineering
更新于2025-09-11 14:15:04
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Applications of Silicon Photonics in Sensors and Waveguides || New Approach to Mach-Zehnder Interferometer (MZI) Cell Based on Silicon Waveguides for Nanophotonic Circuits
摘要： In this chapter, we present a new scheme for Mach-Zehnder Interferometer (MZI) structure based on only one 4×4 multimode interference (MMI) coupler. We design the new MZI cell on the silicon on insulator (SOI) platform. The MZI based on directional coupler and 2×2 MMI coupler is also investigated in detail. The new MZI cell is a basic building block for photonic applications such as optical quantum gate, optical computing and reconfigurable processors. The numerical simulations show that our approach has advantages of compact size, ease of fabrication with the current complementary metal oxide semiconductor (CMOS) circuitry.
关键词： multimode interference,finite difference time difference,directional coupler,modified effective index method,multimode waveguide,finite difference method,silicon on insulator
更新于2025-09-11 14:15:04
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Design of Microdisk-Shaped Ge on Si Photodetector with Recess Structure for Refractive-Index Sensing
摘要： In this paper, we introduce a disk-shaped Ge-on-Si photodetector for refractive-index difference sensing at an operating wavelength of 1550 nm. For the implementation of a small-scale sensor, a Ge layer was formed on top of a Si layer to increase the absorption coefficient at the expense of the light-detection area. Additionally, the sensor had a ring waveguide structure along the edge of the disk formed by a recess into the inner part of the disk. This increased the interaction between the dominant optical mode traveling along the edge waveguide and the refractive index of the cladding material to be sensed, and conclusively increased detection sensitivity. The simulation results show that the proposed sensor exhibited a detection sensitivity of >50 nm/RIU (Refractive Index Unit), a quality factor of approximately 3000, and a minimum detectable refractive index change of 0.95 × 10?2 RIU with a small disk radius of 3 μm. This corresponds to 1.67 times the sensitivity without a recess (>30 nm/RIU).
关键词： refractive index sensor,disk resonator,silicon on insulator,germanium photodetector
更新于2025-09-11 14:15:04
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Cryogenic Characterization of 22nm FDSOI CMOS Technology for Quantum Computing ICs
摘要： An approach is proposed to realize large-scale, “high-temperature” and high-fidelity quantum computing ICs based on single- and multiple coupled quantum-dot electron- and hole-spin qubits monolithically integrated with the mm-wave spin manipulation and readout circuitry technology. Measurements of minimum-size 6nmx20nmx80nm Si-channel n-MOSFETs (electron-spin qubit), SiGe-channel p-MOSFETs (hole-spin qubit), and double quantum-dot complementary qubits reveal strong quantum effects in the subthreshold region at 2 K, characteristic of resonant tunneling in a quantum dot. S-parameter measurements of a transimpedance amplifier (TIA) for spin readout show improved performance from 300 K to 2 K. Finally, the qubit-with-TIA circuit has 50Ω output impedance, 78dBΩ transimpedance gain with unity-gain bandwidth of 70 GHz and consumes 3.1 mW.
关键词： CMOS,silicon-on-insulator,quantum information processing,radio frequency,monolithic integrated circuits,semiconductor quantum dots,silicon,cryogenics
更新于2025-09-10 09:29:36
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A differential Hall effect measurement method with sub-nanometre resolution for active dopant concentration profiling in ultrathin doped Si <sub/>1?</sub><i> <sub/>x</sub></i> Ge <i> <sub/>x</sub></i> and Si layers
摘要： In this paper, we present an enhanced differential Hall effect measurement method (DHE) for ultrathin Si and SiGe layers for the investigation of dopant activation in the surface region with sub-nanometre resolution. In the case of SiGe, which constitutes the most challenging process, we show the reliability of the SC1 chemical solution (NH4OH/H2O2/H2O) with its slow etch rate, stoichiometry conservation and low roughness generation. The reliability of a complete DHE procedure, with an etching step as small as 0.5 nm, is demonstrated on a dedicated 20 nm thick SiGe test structure fabricated by CVD and uniformly doped in situ during growth. The developed method is finally applied to the investigation of dopant activation achieved by advanced annealing methods (including millisecond and nanosecond laser annealing) in two material systems: 6 nm thick SiGeOI and 11 nm thick SOI. In both cases, DHE is shown to be a uniquely sensitive characterisation technique for a detailed investigation of dopant activation in ultra-shallow layers, providing sub-nanometre resolution for both dopant concentration and carrier mobility depth profiles.
关键词： contact resistance,sub-nanometre resolution,fully depleted silicon on insulator (FDSOI),carrier mobility,differential Hall effect,dopant activation,laser annealing
更新于2025-09-10 09:29:36