Silicon-based waveguide grating coupler on insulator and preparation method thereof

Abstract

The invention relates to photonic device technical field, concretely providing a silicon-based waveguide grating coupler on an insulator and a preparation method thereof. The grating coupler comprises a Silicon-On-Insulator (SOI) chip. The SOI chip is characterized in that: the SOI chip is composed of a silicon substrate, a restriction layer and a top silicon layer, wherein the restriction layer is above the silicon substrate, the top silicon layer is above the restriction layer, a surface of the top silicon layer is provided with diffraction grating, a broad waveguide, a taper waveguide and a submicron waveguide connecting with the taper waveguide are provided at an opposite side of the diffraction grating, and a fiber used for receiving diffracted light is provided above the diffraction grating on the top silicon layer. The invention provides a preparation method of the grating coupler, electron beam exposure and common lithography are combined, which means that fine grating and the submicron waveguide structure are defined by the high precision electron beam exposure and a second silicon etching window is defined by the low precision common lithography, thus technology tolerance of production is substantially raised and integrity of a fine structure is guaranteed.

Description

technical field [0001] The invention relates to the technical field of photonic devices, in particular to a silicon-on-insulator waveguide grating coupler and a preparation method thereof. Background technique [0002] Since the beginning of the new century, with the continuous development of micro-nano optoelectronic integration technology, the integration of chips has become higher and higher, the size of devices has been continuously reduced, and the waveguide used to transmit optical signals has gradually shrunk to the sub-micron scale. Among the many optical waveguide materials used in the communication band, silicon-on-insulator (SOI) materials are easy to produce submicron-level low-loss optical waveguides due to the strong light confinement ability of the waveguide layer; at the same time, the preparation process is compatible with the microelectronic IC process , which greatly reduces the cost of preparing optoelectronic chips, making it one of the most competitive ...

AI Technical Summary

Problems solved by technology

However, as the size of the SOI optical waveguide shrinks, the mode spot size of the light in the waveguide also becomes smaller than 1 μm, while the mode spot size in the optical fiber is 8-10 μm. The matching will lead to the appearance of radiation mode and back reflection, and the light entering such a small-sized waveguide from the optical fiber will often cause a large loss, which brings great difficulties to the on-line test of the device and subsequent packaging. performance is also limited

Therefore, in the field of integrated optoelectronics, although SOI submicron waveguides can be used to make various highly integrated and high-performance optoelectronic devices, the coupling between optical waveguides and optical fibers has always been an urgent problem to be solved.

However, since the optical waveguide is usually etched deeper than the grating, the fabrication of the grating coupler often requires a two-step electron beam lithography and etching process, which not only increases the fabrication cost, but also limits the process tolerance due to overlay errors. also reduced

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