EP-4741895-A1 - OPTICAL DETECTOR, OPTICAL RECEIVING SYSTEM, OPTICAL DETECTION METHOD AND CHIP

EP4741895A1EP 4741895 A1EP4741895 A1EP 4741895A1EP-4741895-A1

Abstract

A photodetector, an optical receiving system, an optical detection method, and a chip are provided. The photodetector includes a microring detector (33) and N microring resonant cavities (32) that are successively arranged and coupled. A 1 st microring resonant cavity (32) is coupled to a waveguide (31), the microring detector (33) is coupled to an N th microring resonant cavity (32). A first coupling coefficient between the waveguide (31) and the 1 st microring resonant cavity (32) is not less than a second coupling coefficient between the microring detector (33) and the N th microring resonant cavity (32). The microring detector (33) is configured to generate a first photocurrent based on a target optical signal. The first photocurrent is used for detecting strength of the target optical signal. The target optical signal is obtained by the microring detector (33) and the N microring resonant cavities (32) by filtering initial optical signals transmitted in the waveguide (31). Extinction ratio of the photodetector is higher.

Inventors

REN, Yang

Assignees

Huawei Technologies Co., Ltd.

Dates

Publication Date: 20260513
Application Date: 20240130

Claims (20)

A photodetector, wherein the photodetector is coupled to a waveguide, the photodetector comprises a microring detector and N microring resonant cavities that are successively arranged, wherein N is an integer greater than or equal to 1, a 1 st microring resonant cavity in the N microring resonant cavities is coupled to the waveguide and a coupling coefficient is a first coupling coefficient, the microring detector is coupled to an N th microring resonant cavity in the N microring resonant cavities and a coupling coefficient is a second coupling coefficient, and the first coupling coefficient is greater than or equal to the second coupling coefficient; and the microring detector is configured to generate a first photocurrent based on a target optical signal, wherein the first photocurrent is used for detecting strength of the target optical signal, and the target optical signal is obtained by the microring detector and the N microring resonant cavities by filtering initial optical signals transmitted in the waveguide.
The photodetector according to claim 1, wherein N is an integer greater than or equal to 2, two adjacent microring resonant cavities in the N microring resonant cavities are coupled, a coupling coefficient between every two adjacent microring resonant cavities in the N microring resonant cavities is a third coupling coefficient, the first coupling coefficient is greater than or equal to the third coupling coefficient, and the second coupling coefficient is less than or equal to the third coupling coefficient.
The photodetector according to claim 2, wherein N is an integer greater than 2, a third coupling coefficient between an intermediate resonant cavity and a previous microring resonant cavity is greater than or equal to a third coupling coefficient between the intermediate resonant cavity and a next microring resonant cavity, and the intermediate resonant cavity is a microring resonant cavity other than the 1 st microring resonant cavity and the N th microring resonant cavity in the N microring resonant cavities.
The photodetector according to any one of claims 1 to 3, wherein the microring detector and the N microring resonant cavities have different radiuses.
The photodetector according to any one of claims 1 to 4, wherein a loss coefficient of the microring detector is greater than a loss coefficient of each of the N microring resonant cavities.
The photodetector according to any one of claims 1 to 5, wherein a first optical-to-electrical conversion structure is disposed on the microring detector; and the first optical-to-electrical conversion structure is configured to generate the first photocurrent based on the target optical signal.
The photodetector according to any one of claims 1 to 6, wherein a first tuner is disposed on the microring detector; and the first tuner is configured to adjust a first resonant wavelength of the microring detector to a wavelength of the target optical signal, wherein the first resonant wavelength is a center wavelength in a wavelength range of the target optical signal.
The photodetector according to any one of claims 1 to 7, wherein a second optical-to-electrical conversion structure is disposed on each of the N microring resonant cavities; and the second optical-to-electrical conversion structure is configured to generate a second photocurrent, wherein the second photocurrent is used for detecting the strength of the target optical signal.
The photodetector according to any one of claims 1 to 8, wherein a second tuner is disposed on each of the N microring resonant cavities; and the second tuner is configured to adjust a second resonant wavelength of each microring resonant cavity to the wavelength of the target optical signal, wherein the second resonant wavelength is a center wavelength in a wavelength range of an optical signal transmitted in each microring resonant cavity.
An optical receiving system, wherein the optical receiving system comprises an optical detection array, the optical detection array comprises a waveguide and at least one photodetector, the at least one photodetector is separately coupled to the waveguide, and each of the at least one photodetector is the photodetector according to any one of claims 1 to 9; the waveguide is configured to receive initial optical signals transmitted by an optical transmitter; and each of the at least one photodetector is configured to generate a first photocurrent, wherein the first photocurrent is used for detecting strength of an optical signal of a corresponding wavelength in the initial optical signals, and a wavelength of an optical signal detected by each photodetector is different.
The optical receiving system according to claim 10, wherein the optical receiving system further comprises a receiver array and a receiver circuit, the receiver array comprises at least one transimpedance amplifier and at least one operational amplifier, a quantity of the at least one transimpedance amplifier, a quantity of the at least one operational amplifier, and a quantity of the at least one photodetector are the same, one transimpedance amplifier is connected to one operational amplifier, one transimpedance amplifier is connected to one photodetector, and the at least one operational amplifier is connected to the receiver circuit; the transimpedance amplifier is configured to convert the first photocurrent into a first photovoltage; the operational amplifier is configured to amplify the first photovoltage to obtain an amplified photovoltage, and send the amplified photovoltage to the receiver circuit; and the receiver circuit is configured to receive the amplified photovoltage.
An optical detection method, wherein the method is applied to a photodetector, the photodetector is coupled to a waveguide, the photodetector comprises a microring detector and N microring resonant cavities that are successively arranged, wherein N is an integer greater than or equal to 1, a 1 st microring resonant cavity in the N microring resonant cavities is coupled to the waveguide and a coupling coefficient is a first coupling coefficient, the microring detector is coupled to an N th microring resonant cavity in the N microring resonant cavities and a coupling coefficient is a second coupling coefficient, and the first coupling coefficient is greater than or equal to the second coupling coefficient; and the method comprises: generating, by the microring detector, a first photocurrent based on a target optical signal, wherein the first photocurrent is used for detecting strength of the target optical signal, and the target optical signal is obtained by the microring detector and the N microring resonant cavities by filtering initial optical signals transmitted in the waveguide.
The method according to claim 12, wherein N is an integer greater than or equal to 2, two adjacent microring resonant cavities in the N microring resonant cavities are coupled, a coupling coefficient between every two adjacent microring resonant cavities in the N microring resonant cavities is a third coupling coefficient, the first coupling coefficient is greater than or equal to the third coupling coefficient, and the second coupling coefficient is less than or equal to the third coupling coefficient.
The method according to claim 12 or 13, wherein N is an integer greater than 2, a third coupling coefficient between an intermediate resonant cavity and a previous microring resonant cavity is greater than or equal to a third coupling coefficient between the intermediate resonant cavity and a next microring resonant cavity, and the intermediate resonant cavity is a microring resonant cavity other than the 1 st microring resonant cavity and the N th microring resonant cavity in the N microring resonant cavities.
The method according to any one of claims 12 to 14, wherein the microring detector and the N microring resonant cavities have different radiuses.
The method according to any one of claims 12 to 15, wherein a loss coefficient of the microring detector is greater than a loss coefficient of each of the N microring resonant cavities.
The method according to any one of claims 12 to 16, wherein a first optical-to-electrical conversion structure is disposed on the microring detector; and generating, by the microring detector, the first photocurrent based on the target optical signal comprises: generating, by the first optical-to-electrical conversion structure, the first photocurrent based on the target optical signal.
The method according to any one of claims 12 to 17, wherein a first tuner is disposed on the microring detector; and before generating, by the microring detector, the first photocurrent based on the target optical signal, the method further comprises: adjusting, by the first tuner, a first resonant wavelength of the microring detector to a wavelength of the target optical signal; and filtering, by the microring detector, the initial optical signals based on the first resonant wavelength, to obtain the target optical signal, wherein the first resonant wavelength is a center wavelength in a wavelength range of the target optical signal.
The method according to any one of claims 12 to 18, wherein a second optical-to-electrical conversion structure is disposed on each of the N microring resonant cavities; and the method further comprises: generating, by the second optical-to-electrical conversion structure, at least one second photocurrent, wherein the second photocurrent is used for detecting the strength of the target optical signal.
The method according to any one of claims 12 to 19, wherein a second tuner is disposed on each of the N microring resonant cavities; and before generating, by the microring detector, the first photocurrent based on the target optical signal, the method further comprises: adjusting, by the second tuner, a second resonant wavelength of the microring resonant cavity to the wavelength of the target optical signal; and filtering, by the microring resonant cavity, the initial optical signals based on the second resonant wavelength, to obtain the target optical signal, wherein the second resonant wavelength is the center wavelength in the wavelength range of the target optical signal.

Description

This application claims priority to Chinese Patent Application No. 202311107881.2, filed on August 29, 2023 and entitled "PHOTODETECTOR, OPTICAL RECEIVING SYSTEM, OPTICAL DETECTION METHOD, AND CHIP", which is incorporated herein by reference in its entirety. TECHNICAL FIELD This application relates to the field of optical communication, and in particular, to a photodetector, an optical receiving system, an optical detection method, and a chip. BACKGROUND In an optical/electrical communication process, a transmit end sends optical signals of a plurality of different wavelengths to a receive end. The optical signals are transmitted via a transmission medium and reach the receive end. An optical receiving system is deployed on a chip of the receive end, and the optical receiving system detects the optical signals via a photodetector, to receive the optical signals. SUMMARY This application provides a photodetector, an optical receiving system, an optical detection method, and a chip, to improve extinction ratio of optical detection. Technical solutions are as follows. According to a first aspect, a photodetector is provided. The photodetector is coupled to a waveguide. The photodetector includes a microring detector and N microring resonant cavities that are successively arranged. N is an integer greater than or equal to 1. A 1st microring resonant cavity in the N microring resonant cavities is coupled to the waveguide and a coupling coefficient is a first coupling coefficient. The microring detector is coupled to an Nth microring resonant cavity in the N microring resonant cavities and a coupling coefficient is a second coupling coefficient, and the first coupling coefficient is greater than or equal to the second coupling coefficient; The microring detector is configured to generate a first photocurrent based on a target optical signal. The first photocurrent is used for detecting strength of the target optical signal. The target optical signal is obtained by the microring detector and the N microring resonant cavities by filtering initial optical signals transmitted in the waveguide. The N microring resonant cavities and the microring detector jointly filter the initial optical signals to obtain the target optical signal, and generate the first photocurrent based on the target optical signal, so that the strength of the target optical signal can be detected. Filtering the initial optical signals can ensure that a wavelength range of the target optical signal obtained through filtering is smaller, to improve extinction ratio. In addition, the microring detector is directly coupled to the Nth microring resonant cavity, so that an insertion loss in a process in which an optical signal is transmitted from the Nth microring resonant cavity to the microring detector can be reduced. The first coupling coefficient between the waveguide and the 1st microring resonant cavity is made to be greater than the second coupling coefficient between the microring detector and the Nth microring resonant cavity, so that it can be ensured that the photodetector exhibits an expected bandwidth, and a characteristic of a flat-top photocurrent response of optical detection is implemented, to detect a more stable optical signal and reduce detection difficulty. In a possible implementation, N is an integer greater than or equal to 2. Two adjacent microring resonant cavities in the N microring resonant cavities are coupled. A coupling coefficient between every two adjacent microring resonant cavities in the N microring resonant cavities is a third coupling coefficient. The first coupling coefficient is greater than or equal to the third coupling coefficient. The second coupling coefficient is less than or equal to the third coupling coefficient. A value relationship between the first coupling coefficient, the second coupling coefficient, and the third coupling coefficient is ensured, so that it can be further ensured that the photodetector exhibits an expected bandwidth, and a characteristic of a flat-top photocurrent response of optical detection is implemented. In a possible implementation, N is an integer greater than 2, a third coupling coefficient between an intermediate resonant cavity and a previous microring resonant cavity is greater than or equal to a third coupling coefficient between the intermediate resonant cavity and a next microring resonant cavity, and the intermediate resonant cavity is a microring resonant cavity other than the 1st microring resonant cavity and the Nth microring resonant cavity in the N microring resonant cavities. A value relationship between the third coupling coefficient between the intermediate resonant cavity and the previous microring resonant cavity and the third coupling coefficient between the intermediate resonant cavity and the next microring resonant cavity is defined, so that it is further ensured that the photodetector can exhibit an expected bandwidth, and a characteristic of a flat-to