LD Module Multiplexer Using Intersecting Beam Axes
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Solution Overview
Problem
Reducing the size of LD modules while maintaining coupling efficiency, as decreasing the focal length of the F-axis converging lens increases the incidence angle of laser beams entering the optical fiber, leading to reduced coupling efficiency due to beams exceeding the acceptance angle of the fiber.
Innovation Solution
A multiplexer that outputs a beam bundle with optical axes in a single plane, where the extensions of these beams intersect at a single point closer to the converging lens than its focal point, allowing for a smaller radius of curvature without decreasing coupling efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the focal length of the F-axis converging lens is reduced to decrease module size, then the distance between the lens and optical fiber is reduced, but the incidence angle of laser beams increases causing coupling efficiency to deteriorate
Solution Approach 1:
The patent changes the spatial arrangement of laser beams from parallel propagation to intersecting propagation in a single plane. By making the optical axes intersect at a point closer to the lens than the focal point, the system creates a new spatial configuration that allows reduced focal length while maintaining acceptable incidence angles for coupling efficiency.
Solution Approach 2:
The patent changes the parameter of beam intersection position from the traditional focal point to a point closer to the lens. This parameter change allows the system to achieve compact size while controlling the incidence angle of beams entering the optical fiber, thereby maintaining coupling efficiency despite the reduced focal length.
2Volume of moving object
If the focal length of the F-axis converging lens is reduced, then the radius of curvature can be smaller, but aberration effects increase leading to degraded beam quality
Solution Approach 1:
The patent introduces a new spatial dimension by arranging all laser beam optical axes to intersect at a single point in a single plane. This dimensional arrangement compensates for the increased aberration effects that would normally result from using a lens with smaller radius of curvature, thereby maintaining beam quality in compact modules.
Solution Approach 2:
The patent changes the intersection point parameter from the focal point to a point closer to the lens. This parameter modification optimizes the balance between compact size and beam quality by reducing the propagation distance through the lens, thereby minimizing aberration accumulation while still achieving effective beam convergence.
3Device complexity
If parallel laser beams are used, then the optical system is simple, but the distance from the lens to the beam intersection point cannot be reduced
Solution Approach 1:
The patent changes the fundamental parameter of beam arrangement from parallel to intersecting in a single plane. This single parameter change enables the beam intersection point to be positioned closer to the lens without requiring complex optical components, thereby achieving compact design while maintaining system simplicity.
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
Enables a reduction in LD module size by minimizing the distance between the converging lens and the intersection point, reducing the incidence angle and aberration effects, thus maintaining high coupling efficiency.
Implementation Method 1
a converging lens converging the beam bundle outputted from the output section
Implementation Method 2
Each of the laser beams emitted from the LD elements in the z-axis positive direction, respectively, is reflected into a y-axis positive direction by a corresponding mirror surface 14a
Data Source
AI summary
A multiplexer includes: an output section outputting a beam bundle made of a plurality of laser beams whose F-axis directions are aligned; and an F-axis converging lens causing the beam bundle outputted from the output section to be converged in the F-axis direction. Optical axes of the plurality of laser beams constituting the beam bundle outputted from the output section intersect with each other at a single point without relying on the F-axis converging lens.