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High-performance silicon-on-insulator grating coupler with completely vertical emission.
Optics Express
|September 26, 2015
Summary
Researchers achieved high-performance grating couplers with vertical emission using critical coupling. This silicon-on-insulator device offers low loss and minimal back reflection for fiber optic applications.
Area of Science:
- Photonics and Optical Engineering
- Materials Science
Background:
- Grating couplers are essential for interfacing optical fibers with photonic integrated circuits.
- Achieving high coupling efficiency and vertical emission simultaneously remains a challenge.
Purpose of the Study:
- To investigate the physical concept of critical coupling for high-performance grating couplers.
- To design and numerically validate a grating coupler with vertical emission on silicon-on-insulator (SOI).
Main Methods:
- Numerical simulations based on critical coupling principles.
- Design of a grating coupler structure for 1310 nm wavelength operation.
- Analysis of coupling loss, spectral bandwidth, and back reflection.
Main Results:
- A coupling loss of -1.46 dB was achieved when coupled to a standard single-mode fiber.
- A spectral full-width-half-maximum (FWHM) of 20 nm was demonstrated.
- A back reflection of -24 dB was obtained without full optimization.
Conclusions:
- Critical coupling enables high-performance grating couplers with excellent vertical emission.
- The proposed design offers practical advantages by relaxing lithography requirements.
- This work advances SOI-based photonic integration.
