Optical Module APD Bias Control via Segmented Photodiodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical receivers face challenges in maintaining constant electrical signal output due to variations in light polarization and electrical crosstalk between photodiodes, affecting the bias voltage control of avalanche photodiodes.
Innovation Solution
An optical module design that includes a light-receiving device and an avalanche photodiode (APD), where the light-receiving device receives a portion of the optical signal and outputs a first photocurrent, while the APD receives the remaining signal, with a control unit adjusting the bias voltage to maintain a preset ratio of photocurrents, independent of light polarization and crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the bias voltage applied to the APD is controlled based on the output from the PIN-PD that receives light reflected by the APD, then the bias voltage control function is achieved, but the output current from the PIN-PD varies depending on the polarization of the light
Solution Approach 1:
The incident optical signal is divided into two portions: one portion is reflected by the APD and received by the PIN-PD for monitoring, while the other portion passes through the APD for signal detection. This segmentation allows independent optimization of the monitoring path and signal detection path, enabling polarization-independent control while maintaining APD performance
Solution Approach 2:
The PIN-PD acts as an intermediary device that monitors the reflected light portion to provide feedback for bias voltage control. By using the PIN-PD to sense the optical signal characteristics and convert them to electrical signals for control purposes, the system achieves stable bias voltage regulation without being affected by polarization variations
2Device complexity
If the PIN-PD and the APD are integrally formed in the same substrate, then the device integration is achieved, but the output current from the PIN-PD is affected by the APD through electrical crosstalk
Solution Approach 1:
The integrated device is segmented into distinct functional regions: the APD region for signal detection and the PIN-PD region for monitoring. By spatially separating these functions within the same substrate and providing independent electrical contacts for each region, the design achieves integration while minimizing electrical crosstalk between the two photodiodes
Solution Approach 2:
Different regions of the substrate are optimized for different functions: the APD region is designed with high gain characteristics for weak signal detection, while the PIN-PD region is designed with low noise characteristics for accurate monitoring. This local optimization allows each region to perform its specific function independently, reducing mutual interference
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design ensures a constant average electrical signal output by controlling the bias voltage based on the photocurrents from both devices, effectively isolating the APD from polarization-dependent variations and crosstalk, thereby stabilizing the optical-to-electrical conversion efficiency.
Implementation Method 1
The light-receiving device receives a portion of the optical signal and outputs a first photocurrent
Implementation Method 2
The APD outputs a second photocurrent corresponding to the rest portion of the optical signal
Implementation Method 3
avalanche photodiode (APD) with a multiplication factor
Data Source
AI summary
The present invention provides an optical receiver that uses an avalanche photodiode (APD) whose multiplication factor m is controlled to compensate the temperature dependence thereof. An optical module of the present invention includes a light-receiving device in addition to the APD. The light-receiving device may be a semiconductor thin film or a PIN photodiode, and is disposed in front of the APD. Accordingly, the light-receiving device receives a portion of signal light, and transmits a rest portion thereof. The APD receives the rest portion of the signal light. The bias voltage applied to the APD is so controlled that a first photocurrent generated in the light-receiving device and a second photocurrent generated in the APD maintain a constant ratio.