Liquid Light Guide Coupling for Poor-Beam-Quality Semiconductor Lasers
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Solution Overview
Problem
High-power semiconductor lasers with poor beam quality face challenges in being coupled into optical fibers due to beam quality limitations, leading to significant coupling losses and inefficiencies, particularly in medical laser applications where uniform light intensity distribution is required.
Innovation Solution
A semiconductor laser coupling, transmission, and imaging apparatus using a liquid light guide is developed, comprising a laser source, a low refractive index tube body with rod mirrors and light guide liquid, and an imaging lens, which allows for total internal reflection and homogenization of the laser beam, ensuring uniform power distribution at the output end.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If optical fibers are used for semiconductor laser coupling, then the laser beam can be transmitted, but high-power semiconductor lasers with poor beam quality cannot be effectively coupled due to beam quality limitations
Solution Approach 1:
The patent changes the key parameter from optical fiber to liquid light guide, which fundamentally alters the acceptance characteristics. The liquid light guide has a much larger numerical aperture (up to 75 degrees full angle) compared to optical fibers (0.15-0.37 NA), enabling it to accept laser beams with poor quality and high BPP values that optical fibers cannot couple effectively.
2Quantity of substance
If the fiber core diameter is increased to accept larger laser beams, then more power can be transmitted, but the rigidity and flexibility limitations make it very difficult for the fiber core diameter to exceed 1000 um
Solution Approach 1:
The patent uses a liquid light guide filled with liquid medium instead of a solid optical fiber. The liquid can be contained in a flexible tube with much larger diameter (caliber typically 2mm, 3mm, 5mm, 8mm or more) without the mechanical constraints that limit optical fiber core diameters to under 1000 micrometers, enabling transmission of higher power lasers.
3Reliability
If the numerical aperture of the optical fiber is increased to accept larger incidence angles, then coupling efficiency improves, but the beam quality requirement (BPP) still cannot be met for high-power semiconductor lasers
Solution Approach 1:
The patent changes the numerical aperture parameter from 0.15-0.37 (optical fiber) to up to 0.75 (liquid light guide with 75 degrees full incidence angle). This tenfold increase in NA allows the system to accept high-power semiconductor laser beams with large BPP values (up to 600 mm*degree) that would be completely rejected by conventional optical fibers.
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
The apparatus effectively couples and transmits high-power semiconductor lasers with poor beam quality, achieving highly uniform power density distribution suitable for medical applications, such as dermatologic surgery, by using a liquid light guide that can handle higher peak powers and reduce coupling losses.
Implementation Method 1
the semiconductor laser beam is totally reflected inside the accommodating cavity and exits from the exiting end surface
Implementation Method 2
are focused by a convex lens onto an end surface of an optical fiber
Data Source
AI summary
The present disclosure discloses a semiconductor laser coupling, transmission, and imaging apparatus using a liquid light guide, and a device. The apparatus includes: a laser source; a liquid light guide, including a low refractive index tube body, two rod mirrors, light guide liquid, and an imaging lens; wherein the tube body has an accommodating cavity penetrating through the tube body in a lengthwise direction; the two rod mirrors are plugged at two ends of the accommodating cavity, and the light guide liquid fills the accommodating cavity; a first rod mirror located on the light entering side has a coupling end surface, and a second rod mirror located on the light exiting side has an exiting end surface. The present disclosure solves, by using the liquid light guide to replace an optical fiber, the problem that high-power semiconductor laser with poor beam quality cannot be coupled into the optical fiber.