A grating coupler for exciting high-order modes in few-mode fibers

Abstract

The invention discloses a grating coupler for exciting the high-order mode of a few-mode optical fiber. The grating coupler comprises an SOI substrate; a waveguide core layer is arranged on the SOI substrate; and a plurality of notch grooves are formed in the waveguide core layer. According to an LP11a mode, an LP11b mode and an LP21b mode in the few-mode optical fiber, which can be excited by thegrating coupler, the notch grooves are distributed in a manner that the plurality of notch grooves are divided into two groups with a distance D formed therebetween along a light propagation direction, distributed in a manner that the plurality of notch grooves are divided into a left side group and a right side group with a distance D2 formed therebetween along the upper surface of the waveguidecore layer in a direction perpendicular to the light propagation direction, or are distributed in a mode integrating the above two manners, wherein D1 and D2 both make the phase difference of light fields diffracted from the grating coupler to be Pi. The grating coupler of the invention is used for realizing the excitation of the LP11a mode, the LP11b mode and the LP21b mode in the few-mode optical fiber; and the notch grooves can be formed with one-time electron beam etching, and therefore, processing complexity can be greatly decreased, and the grating coupler is easy to process and manufacture.

Description

technical field [0001] The invention relates to silicon-based photonics and chip-level optical interconnection technology, which belongs to the field of integrated optics and micro-nano optics. Background technique [0002] Emerging information technologies such as optical communication, optical interconnection, and optical sensing based on silicon photonic integration show the development trend of building new information hardware, and are becoming an important foundation for a new generation of information systems and networks. For silicon photonic integrated chips, a key issue that cannot be ignored is the input and output of optical signals. In particular, silicon is used as an indirect bandgap material, and its luminous efficiency has not yet met the requirements for use. The existing technology needs to introduce an independent light source from the outside of the photonic chip or use an on-chip hybrid integrated optical gain material. Therefore, photonic integrated c...

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Problems solved by technology

However, the excitation of some modes needs to enter higher-order modes from the waveguide, so an additional waveguide mode converter is required, which increases the complexity of the structure

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