20GHz traveling wave optical waveguide detector

Abstract

The invention discloses a 20GHz traveling wave optical waveguide detector which is applied to the technical field of photoelectricity and is used for solving the problems of non-uniform distribution of photocurrent along a waveguide direction, relatively large coupling loss and limited incident light power of an existing waveguide type detector. According to the invention, firstly, an optical waveguide structure is reasonably designed according to a super-mode matching theory to change the exponential distribution of the photocurrent, so that the photocurrent is distributed in a relatively long waveguide range as much as possible, and the high quantum efficiency is ensured while the photocurrent is uniform; secondly, a method for realizing the optical waveguide and the microwave waveguidein the same structure is provided, and waveguide characteristic impedance is designed to match load impedance, so that traveling wave transmission of a transmission line is realized, and the limitation of RC time constants on bandwidth is overcome; and characteristic impedance of the detector is designed to be 50 Omega to match a back-end coplanar waveguide structure and an external coaxial cable.

Description

technical field [0001] The invention belongs to the field of optoelectronic technology, in particular to a waveguide photodiode. Background technique [0002] The high-power high-speed photodetector is a detection device based on the interaction between light and matter, and its function is to convert the incident light signal into a high-power microwave signal. High-power high-speed optical detector is an indispensable device in optically controlled phased array radar, ultra-high-speed test system and optical fiber LAN communication, and its performance plays a decisive role in the whole system. However, the photodetector is limited by its inherent physical factors, such as the RC time constant and carrier transit time limit the bandwidth, making it difficult to achieve high-speed response, and the length of the waveguide limits the responsivity, so it is difficult to achieve both high speed and high power. . [0003] Conventional vertical-incidence photodetectors cannot ...

AI Technical Summary

Problems solved by technology

However, the current waveguide detector also has the following problems: the photocurrent is unevenly distributed along the waveguide direction, it is exponentially attenuated, and the coupling loss is large; the photocurrent is very strong at the front end of the waveguide, and gradually weakens in the direction of propagation. The front end of the waveguide determines the photocurrent. The saturation value of , which limits the incident optical power

[0006] In 2008, in order to solve the problem of uneven photocurrent distribution and large coupling loss of waveguide detectors, the University of California, San Diego proposed a Directional Coupling Waveguide Photodetector (DCPD, Directional Coupling Waveguide Photodetector) scheme.

[0007] However, the air gap at the upper end of the coupling layer of this structure has a great influence on the coupling length and absorption length, and when the width of the air gap changes, it will lead to uneven photocurrent distribution.

The photolithographic etching process of the air gap on the coupling layer is also not easy to fabricate

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