Laser Module Current Allocation for Low-Loss Fiber Coupling
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Solution Overview
Problem
Existing laser modules face a trade-off between reducing coupling loss and maintaining high brightness of laser beams emitted from semiconductor devices, as the divergence angle of longer optical path length beams increases, leading to inefficiencies in optical coupling with optical fibers.
Innovation Solution
A laser module configuration where semiconductor laser devices with longer optical path lengths receive a smaller drive current than those with shorter path lengths, reducing divergence and ensuring all beams are within the optical fiber's acceptance angle, thereby minimizing coupling loss and maintaining high brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the optical path length is increased to accommodate multiple semiconductor laser devices, then the number of devices that can be integrated increases, but the divergence angle of the laser beam increases leading to higher coupling loss
Solution Approach 1:
The patent changes the drive current parameter for different semiconductor laser devices based on their optical path lengths. Devices with longer optical path lengths receive smaller drive currents to reduce beam divergence and maintain coupling efficiency, while devices with shorter path lengths receive larger currents. This dynamic parameter adjustment resolves the contradiction between integrating multiple devices and maintaining low coupling loss.
2Power
If the drive current is increased to maintain high output power, then the laser beam intensity increases, but the divergence angle increases causing the beam to exceed the optical fiber's acceptance angle
Solution Approach 1:
The patent applies local quality by providing different drive currents to different semiconductor laser devices based on their individual optical path lengths. Each device operates at an optimized current level that maintains high output power while keeping the beam divergence within acceptable limits for efficient coupling. This localized optimization resolves the contradiction between power output and coupling efficiency.
3Device complexity
If a single drive current is supplied to all semiconductor laser devices, then the system complexity is reduced, but the optical path length differences cause varying divergence angles and coupling losses
Solution Approach 1:
The patent implements parameter changes by supplying different drive currents to different semiconductor laser devices according to their optical path lengths. This is achieved through a current supply unit that can independently control the drive current for each device or group of devices, optimizing coupling efficiency while managing system complexity through structured current distribution.
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 reduces coupling loss and maintains high brightness of the output laser beam by adjusting drive currents based on optical path lengths, ensuring efficient optical coupling and increased incidence density within the fiber's light-receiving range.
Implementation Method 1
a condenser lens configured to condense laser beams emitted from the plurality of semiconductor laser devices and optically couple the laser beams to the optical fiber
Data Source
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AI summary
The present invention provides a laser module capable of reducing coupling loss of laser beams that are emitted from a plurality of semiconductor laser devices and optically coupled to an optical fiber and of maintaining high brightness of a laser beam outputted from the optical fiber. A laser module 2 has an optical fiber 20, a plurality of semiconductor laser devices 10A-10H, a condenser lens 40 configured to condense laser beams 70A-70H emitted from the semiconductor laser devices 10A-10H and optically couple the laser beams to the optical fiber 20, lead terminals 53 to supply a first drive current to the semiconductor laser devices 10A-10D, and lead terminals 54 to supply a second drive current that is smaller than the first drive current to the second semiconductor laser devices 10E-10H. The optical path length of the laser beam from a laser output surface of the semiconductor laser devices 10E-10H to an incidence surface 41 of the condenser lens 40 is longer than the optical path length of the laser beam from a laser output surface of the semiconductor laser devices 10A-10D to the incidence surface 41 of the condenser lens 40.