Grating coupling structure based on back process and preparation method

Abstract

The invention provides a grating coupling structure based on a back process. A nonmetal structure reflector layer is arranged on a waveguide diffraction grating layer, so that the coupling efficiency of the grating is greatly improved, and the grating-optical fiber coupling loss is reduced. The reflector layer adopts at least one distributed Bragg reflector structure or grating reflector structure, has no metal absorption problem, is more resistant to high temperature, is more compatible with a traditional optical device without causing unnecessary loss, and has no pollution problem of a rear-section process of a metal reflector. The invention further provides a preparation method of the grating coupling structure based on the back process, a standard wafer is adopted as an initial wafer, the single-step etching process is simple, and the optical coupling reflection requirement of a larger bandwidth can be met through single deposition etching; on the basis of not influencing the original architecture, the reflection height requirements of different wave bands can be flexibly met according to the design requirements, so that corresponding advantages are achieved.

Description

technical field [0001] The invention relates to the technical field of photonic devices, and relates to a waveguide grating coupling structure, in particular to a grating coupling structure based on a back-to-back process and a corresponding preparation method. Background technique [0002] Silicon-on-insulator (SOI), based on silicon-on-insulator (SOI), is considered to be an important direction for the future development of integrated optics because of its CMOS process compatibility, ultra-small integration, and active and passive monolithic integration. One of the key problems to be solved in the development of SOI-based integrated optics is the coupling problem between fiber and chip. The core size of a single-mode fiber is generally 10.4 μm, while the width of a single-mode Si waveguide based on SOI is usually sub-micron, and the huge size difference will lead to a large coupling loss. [0003] One of the commonly used coupling structures is the grating coupling struct...

AI Technical Summary

Problems solved by technology

Commonly used reflectors are usually located on the BOX layer of the SOI wafer to increase the front light reflection efficiency of the grating. This design greatly reduces the coupling efficiency of the grating-fiber, but it needs different reflector heights for different light bands. , this architecture limits system compatibility and scalability to a certain extent

At present, another type of coupling grating adopts back-to-back technology, but it often uses metal reflectors, and there is a problem of process pollution in the back end of metal reflectors.

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