研究目的
To design broadband grating couplers using a gradient-based optimization strategy for silicon photonics applications, achieving specified target bandwidths without geometric constraints.
研究成果
The inverse design approach successfully produced broadband grating couplers with 3 dB bandwidths exceeding 100 nm and efficiencies from -3.0 to -5.4 dB. Experimental results validated the simulations, showing up to 120 nm bandwidths with minor discrepancies due to fabrication issues. This method offers flexibility for wideband applications in silicon photonics.
研究不足
The method may lead to multiple peaks in spectra for large bandwidths, increased back reflections, and sensitivity to fabrication variations like overetching. Optimization could be stopped earlier for efficiency, and additional constraints might be needed for uniform performance.
1：Experimental Design and Method Selection:
The grating couplers were designed using a gradient-based inverse design approach with adjoint optimization, involving continuous and discrete stages for permittivity variation and binary conversion. Simulations used finite-difference frequency-domain (FDFD) and finite-difference time-domain (FDTD) methods.
2：Sample Selection and Data Sources:
Designs were based on 220 nm silicon-on-insulator (SOI) with various partial-etch fractions (40%, 60%, 80%, 100%) and target bandwidths (40-120 nm). Fabricated devices were on SOI wafers.
3：List of Experimental Equipment and Materials:
Equipment included electron-beam lithography system (JEOL JBX-6300FS), plasma etcher, tunable CW source (Agilent 81989A), supercontinuum source (Fianium SC400-4), optical spectrum analyzer, photodetectors, piezo controllers, polarization controllers, and materials like ZEP-520A resist and SMF-28 fibers.
4：Experimental Procedures and Operational Workflow:
Fabrication involved spinning resist, e-beam lithography, plasma etching, resist stripping, and HF dip. Characterization used a fiber-in/fiber-out setup with automated alignment, reference spectrum measurement, and coupling efficiency calculation.
5：Data Analysis Methods:
Data were analyzed by comparing simulated and measured spectra, calculating 3 dB bandwidths and efficiencies, and assessing waveguide losses through length variation.
独家科研数据包，助您复现前沿成果，加速创新突破
获取完整内容-
electron-beam lithography system
JBX-6300FS
JEOL
Used for patterning the grating couplers on the silicon-on-insulator wafer during fabrication.
-
tunable continuous-wave source
81989A
Agilent
Used as a light source for alignment in the characterization setup.
-
supercontinuum source
SC400-4
Fianium
Used for measuring coupling efficiency in the characterization setup.
-
optical spectrum analyzer
Used to record spectra during characterization.
-
photodetector
Used to measure power during alignment and characterization.
-
piezo controller
Used for automated alignment of fibers in the characterization setup.
-
polarization controller
Used to adjust polarization of the light source in the characterization setup.
-
FDTD software
Lumerical
Used for fine discretization simulations to verify device efficiencies.
-
登录查看剩余6件设备及参数对照表
查看全部
