Spot size converter and preparation method thereof

Abstract

The invention discloses a spot size converter and a preparation method thereof. The spot size converter comprises a silicon substrate, a buried oxide layer, a first waveguide located on the buried oxide layer, at least two second waveguides parallel to the first waveguide, an upper cladding and at least two low-refractive-index waveguides, wherein the second waveguides are arranged on the two sides of the first waveguide; the width of the first waveguide is gradually reduced from the incident surface to the emergent surface; the upper cladding is located on the buried oxide layer, the first waveguide and the second waveguides; the at least two low-refractive-index waveguides are located in the upper cladding, are higher than the first waveguide and are parallel to the first waveguide; thelow-refractive-index waveguides are arranged on the two sides of the first waveguide; the width of the low-refractive-index waveguide is gradually increased from the light incident surface to the light emergent surface, and the refractive index of the low-refractive-index waveguide is lower than that of the first waveguide. According to the invention, the alignment tolerance is large, and the substrate absorption loss is small.

Description

technical field [0001] The invention belongs to the field of silicon photonics technology, and in particular relates to a mode spot converter and a preparation method thereof. Background technique [0002] In order to realize the matching between the light source / fiber output mode field and the silicon waveguide mode field, an inverted tapered mode-spot conversion structure or a grating coupler is mostly used at present. The principle of the inverted cone mode spot conversion structure is that the size of the waveguide gradually decreases. When the size of the waveguide is small to a certain value, the waveguide cannot achieve the confinement of the light, so as to achieve the amplification of the mode field and match the output mode field of the light source / fiber. ; However, the alignment tolerance of the inverted cone mode spot conversion structure is small, and the requirements for alignment accuracy of the light source / fiber are relatively high. Although the grating co...

AI Technical Summary

Problems solved by technology

Although the grating coupler has a large alignment tolerance when coupling with the light source / fiber, it has a large loss; and for an edge-emitting laser (such as a DFB laser) light source, to achieve coupling between the light source and the grating coupler, additional Adding reflective mirrors converts the output direction of the light source from horizontal emission to the direction perpendicular to the grating coupler, and the structure is more complicated

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