A Gradient Match Coupler

Abstract

A gradient matching coupler relates to the field of optical communication integrated devices. The gradient matching coupler includes a gradient silica waveguide, a curved gradient silicon waveguide and a matching area. The gradient silica waveguide is of a conical structure, and gradually narrows along the direction in which light is coupled into a chip. The curved gradient silicon waveguide is disposed in the gradient silica waveguide, and gradually widens. The broadest end of the curved gradient silicon waveguide and the narrowest end of the gradient silica waveguide are in the same plane. The narrowest end of the curved gradient silicon waveguide is a pointed end, and is bent. The distance between the pointed end and the broadest end of the gradient silica waveguide is d1. The materialof the matching area is a matching solution with the refractive index lower than that of silica. The matching area covers the side walls of the gradient silica waveguide. The matching area is dividedinto multiple matching sub areas along the direction in which light is coupled into the chip. The length d0 of the matching sub area connected with the broadest end of the gradient silica waveguide issmaller than d1. The length of the coupler is reduced, and the problem of high back reflection is solved.

Description

technical field [0001] The invention relates to the field of optical communication integrated devices, in particular to a gradual matching coupler. Background technique [0002] The coupling of silicon-based photonic chips to optical fibers is critical. There are two types of silicon-based fiber coupling: grating coupling and end-face coupling. The grating coupler must be incident perpendicular to the chip and has limited bandwidth. The end face coupler generally adopts an inverted cone structure, that is, the silicon waveguide width of the coupler gradually narrows toward the coupling end face. In order to achieve a large mode field matching that of the optical fiber, the buried oxide layer and the silicon substrate coated with the silicon waveguide are generally hollowed out to realize a suspended silica waveguide, and the surrounding silica waveguide is filled with The matching fluid of silica achieves the expansion of the mode field. The coupling of light from the fi...

AI Technical Summary

Problems solved by technology

Current methods only take into account the first process, in the second process, the optical mode field size is still large, so the coupler length is long and the back reflection is high

In addition, the direct coupling of light into the high-index silicon waveguide also brings excessive back reflection

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