Optical waveguide structure for vertically coupled photodetectors

Abstract

The invention relates to an optical waveguide structure for a photodetector coupled in a vertical direction, comprising an intrinsic layer, an absorption layer, an upper waveguide layer, a gap layer, a lower waveguide layer, a cover layer and a substrate sequentially stacked from top to bottom , the gap layer is used as a low refractive index coupling layer between the upper waveguide layer and the lower waveguide layer, and the upper waveguide layer and the lower waveguide layer form a vertical coupler (equivalent to a vertically coupled photodiode) It is used to make the light incident from the lower waveguide layer gradually coupled to the upper waveguide layer, and make the light be absorbed by the absorbing layer while being transmitted in the upper waveguide layer and the lower waveguide layer. The beneficial effect of the invention is that: when the air gap changes in the horizontally coupled photodiode structure, the coupling length and the absorption length will both change, and the drawbacks of difficult fabrication of photoetching and etching processes are solved.

Description

technical field [0001] The invention belongs to the field of optoelectronic technology, and in particular relates to a photodiode. Background technique [0002] Photodetectors are one of the indispensable devices in broadband communication systems, wireless communication systems and high-frequency measurement systems, and are also the core devices in optical receivers. A photodiode is an optical waveguide structure used in photodetectors for photoelectric conversion. The development of high-power and high-speed photodiodes began with the improvement of the traditional PIN (positiveintrinsicnegativediode) photodiode structure; the waveguide photodiode (WaveguideDiode, WD) scheme was proposed in the late 1990s and early 20th century; the direction-coupled photodiode was proposed in the last two years. Diode (DirectionalCouplingPhotoDiode, DCPD) scheme. [0003] like figure 1 As shown, in the traditional PIN photodiode, the incident light is incident from the direction perpe...

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Problems solved by technology

[0006] The purpose of the present invention is to overcome the defects in the prior art that when the air gap on the coupling layer changes, the coupling length and absorption length of the photodiode will change, and propose a photodetector for coupling in the vertical direction The optical waveguide structure

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