Multi-Channel Optical Module Crosstalk Suppression
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Solution Overview
Problem
Conventional multi-channel optical modules face challenges in accurately monitoring optical output power for each wavelength channel in wavelength multiplex optical transmission systems, leading to crosstalk issues due to stray light components and light loss from beam splitters.
Innovation Solution
The proposed multi-channel optical module incorporates a beam splitter and wavelength filters between the beam splitter and monitor PDs, ensuring only specific wavelengths are monitored, thereby preventing stray light from adjacent channels from interfering with the monitoring process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a beam splitter is used to branch output light for monitoring, then optical power monitoring becomes possible, but light loss occurs due to passing loss of the beam splitter
Solution Approach 1:
An optical waveguide is introduced as an intermediary component to guide the branched light from the beam splitter to the monitor photodetector. This waveguide structure minimizes light loss by providing a dedicated optical path that maintains light intensity while enabling monitoring functionality.
2Measurement precision
If monitor PDs are placed on the output side of light source chips, then output power monitoring is possible, but crosstalk is generated due to stray light components from adjacent channels
Solution Approach 1:
The optical path for each wavelength channel is segmented and isolated using wavelength-specific optical waveguides. Each waveguide is designed to transmit only its designated wavelength, physically separating the optical paths to prevent stray light from adjacent channels from reaching the monitor photodetectors, thereby eliminating crosstalk.
Solution Approach 2:
The monitoring system uses feedback control where the monitor photodetector detects the optical power through the wavelength-specific waveguide, and this information is fed back to adjust the light source output to maintain constant power levels, while the waveguide structure ensures only the intended wavelength is monitored.
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 configuration effectively suppresses crosstalk between adjacent channels, maintaining consistent optical power measurements across all channels, even when multiple channels are operated simultaneously.
Implementation Method 1
a plurality of wavelength filters inserted between the beam splitter and each of the plurality of monitor PDs and each wavelength filter transmitting only the wavelength of the light source coupled by the beam splitter
Implementation Method 2
a plurality of monitor PDs for monitoring optical power branched from the beam splitter
Data Source
AI summary
Crosstalk between adjacent channels is suppressed when monitoring optical output power. A multi-channel optical module for multiplexing and outputting a plurality of wavelength channels, which includes a plurality of light sources each having a different wavelength, a plurality of collimator lenses coupled to the respective outputs of the plurality of light sources, a beam splitter coupled to an output of each of the plurality of collimator lenses, a plurality of monitor PDs for monitoring optical power branched from the beam splitter, and a plurality of wavelength filters inserted between the beam splitter and each of the plurality of monitor PDs and each wavelength filter transmitting only the wavelength of the light source coupled by the beam splitter.