Multi-Lane Transmitter Optical Module with Independent Defocus Control
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Solution Overview
Problem
Existing transmitter optical modules face challenges in maintaining stable optical output power across multiple light-emitting elements due to misalignment and varying defocus amounts, leading to scattered optical coupling efficiency when adjusting optical power for one light-emitting diode (LD) affects the others.
Innovation Solution
A transmitter optical module design incorporating a three-lens system where the first lens focuses the optical signal, the second lens converts it into a collimated beam, and the third lens couples the beam with an optical fiber, allowing for independent adjustment of the second lenses along the optical axis to maintain stable optical coupling efficiency across all LDs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the bias current of the semiconductor laser diode is reduced to set the optical power in the preset power, then the optical power is controlled within the preset range, but the resonance frequency of the LD lowers to degrade high frequency performance
Solution Approach 1:
The invention divides the optical power control function into two independent parts: (1) bias current control for basic power level, and (2) defocus control for fine power adjustment. This segmentation allows the bias current to be set at an optimal level for high frequency performance while using defocus to adjust the actual coupled power into the fiber, thus resolving the contradiction between power control and performance maintenance
Solution Approach 2:
The invention introduces defocus as an intermediary mechanism between the laser diode and the optical fiber. By adjusting the focus position of the concentrating lens, the system can control the amount of optical power coupled into the fiber without changing the bias current, thereby maintaining high frequency performance while achieving preset power levels
2Power
If the optical connector is slid along the Z-axis to offset the incident surface of the optical fiber from the focal point of the concentrating lens, then the optical power coupled to the fiber decreases, but this defocus adjustment may not adequately adjust the optical power for all LDs in a multi-LD system
Solution Approach 1:
The invention makes the defocus adjustment capability local to each LD channel by providing independent defocus adjustment mechanisms for each LD-fiber coupling path. This allows each LD to be independently optimized for its specific alignment conditions, ensuring that all LDs in a multi-LD system can achieve adequate power adjustment despite variations in their individual optical axes and coupling efficiencies
3Quantity of substance
If four laser beams are coupled on the end surface of the optical fiber through the unique concentrating lens, then the optical signals from multiple LDs are multiplexed, but the optical coupling efficiency scatters when defocus adjusts only one LD
Solution Approach 1:
The invention segments the optical coupling system into independent adjustable units, where each LD has its own defocus adjustment capability. This segmentation ensures that when one LD is adjusted for optimal coupling, the others can maintain their own optimization, preventing scattering in coupling efficiency across the multi-LD system while still achieving multiplexing of multiple optical signals
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 ensures stable optical output power and maintains optical coupling efficiency within a designed range for all LDs, reducing dispersion and exceeding standard power limitations, while allowing for precise alignment with improved positional accuracy.
Implementation Method 1
a first lens 12 that has a focal point aligned with an optical output point of the transmitting optical device
Implementation Method 2
a second lens 14 that outputs an optical output of the first lens as a collimated beam
Implementation Method 3
a third lens that couples the concentrated optical beam with an optical fiber
Data Source
AI summary
A transmitter optical module that provides an LD, a first lens with a focal point aligned with an optical output point of the LD, a second lens that generates an optical output of the first lens as a concentrated optical signal, and a third lens that provides an optical output of the second lens in an optical fiber. The second lens is set at a position offset toward the third lens from a position at which the second lens outputs a collimated optical signal. The third lens concentrates an optical output thereof within the optical fiber.