LD Module Emitter Width Optimization for Reliability
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Solution Overview
Problem
Increasing the resonator length of a semiconductor laser diode (LD) to enhance reliability and reduce light loss in LD modules leads to a decrease in electrooptic conversion efficiency, making it challenging to maintain high reliability without compromising efficiency in LD modules.
Innovation Solution
The LD module design features a multi-mode laser diode with an emitter width greater than the optical fiber's core diameter, coupled with an optical system that converges the laser beam to ensure it enters the fiber efficiently, eliminating the need for increased resonator length and maintaining electrooptic conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the resonator length of the LD is increased to enhance reliability and reduce light loss, then the heat-dissipating property is improved and light loss in the active layer is reduced, but the electrooptic conversion efficiency decreases
Solution Approach 1:
The invention changes the geometric parameters of the LD, specifically using a broad-area laser diode with a wide emitter width (greater than the fiber core diameter) and optimizing the resonator length to a specific range (0.5-2.0 mm). This parameter optimization allows the laser to achieve reliable operation with reduced light loss while maintaining acceptable electrooptic conversion efficiency by finding the optimal balance point among competing parameters.
Solution Approach 2:
The invention transitions from considering only the resonator length dimension to incorporating the emitter width dimension as a critical parameter. By using a broad-area laser diode where the emitter width exceeds the fiber core diameter, the solution adds a spatial dimension to the problem-solving approach, allowing light density reduction and improved reliability without solely relying on increased resonator length.
2Temperature
If the resonator length of the LD is increased to reduce light loss in the active layer, then the temperature in the active layer is lowered, but the electrooptic conversion efficiency decreases
Solution Approach 1:
The invention optimizes the resonator length parameter to a specific range (0.5-2.0 mm) that balances temperature control and efficiency. By setting the resonator length within this optimized range and combining it with a broad emitter width, the active layer temperature is effectively managed to prevent overheating and maintain stable operation without excessively compromising electrooptic conversion efficiency.
3Reliability
If the emitter width of the LD is made greater than the fiber core diameter to reduce light density, then the reliability of the LD is enhanced, but the coupling efficiency with the fiber may be compromised
Solution Approach 1:
The invention introduces optical elements (lenses or optical systems) as intermediaries between the broad-area laser diode and the optical fiber. These optical components serve as mediators that collect and focus the divergent light from the wide emitter onto the smaller fiber core, enabling effective coupling despite the emitter width being greater than the fiber core diameter. This intermediary approach preserves both the reliability benefits of reduced light density and the coupling efficiency.
4Reliability
If techniques are used to prevent catastrophic optical damages in high-output LDs, then the reliability of the LD is improved, but the electrooptic conversion efficiency may be affected
Solution Approach 1:
The invention changes the operating parameters by using a broad-area laser diode configuration with emitter width greater than the fiber core diameter and optimizing the resonator length to 0.5-2.0 mm. This parameter change fundamentally alters the light distribution and stress characteristics, preventing catastrophic optical damages through reduced light density while maintaining efficient operation and avoiding the need for additional protective techniques that might compromise efficiency.
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 enhances the reliability of the LD module by reducing light density and ensuring efficient coupling with the optical fiber, without decreasing electrooptic conversion efficiency, thus achieving a balance between reliability and efficiency.
Implementation Method 1
an optical system provided between the laser diode and the fiber, the optical system converging a laser beam emitted from the laser diode
Data Source
Figure 1(a)~1(d)
Figure 2
Figure 3
AI summary
An emitter width WLD of an LD (11) is set so as to be greater than a diameter Dc, of a core (121), in an entrance end surface (12S) of an optical fiber (12). An optical system (13) provided between the LD (11) and the optical fiber (12) is configured to cause a diameter DB, of a laser beam, in the entrance end surface (12S) of the optical fiber (12) to become smaller than the diameter Dc, of the core, in the entrance end surface (12S) of the optical fiber (12). This causes an enhancement in reliability of the LD (11) without causing a reduction in efficiency of coupling the LD (11) with the optical fiber (12).