Side Pumped Laser Diode Direct Coupling Gain Medium
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Solution Overview
Problem
Side pumped laser systems are inefficient due to pump radiation divergence, which is often addressed by using optical components like cylindrical lenses and focusing optics, increasing cost and alignment complexity.
Innovation Solution
A side pumped laser design where the pump source is directly incident on the gain medium without optical components, with the pump source closely coupled to the gain medium, allowing divergent radiation to be efficiently coupled, and using a reflective coating on the gain medium to optimize radiation distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If optical components (cylindrical lens, focusing optics) are used to focus pump radiation, then pumping efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent removes the optical components (cylindrical lens, focusing optics) from the pump path, extracting the problematic elements that caused complexity while maintaining pumping efficiency through direct coupling of the pump source to the gain medium
Solution Approach 2:
The pump source is designed to directly illuminate the gain medium without requiring external optical components to shape or focus the beam. The system serves itself by using the natural divergence of the pump source as the pumping mechanism, eliminating the need for additional optical elements
2Loss of energy
If optical components are used to focus pump radiation, then pumping efficiency is improved, but alignment precision requirements increase
Solution Approach 1:
By removing the optical components from the system, the patent eliminates the alignment precision requirements that would be necessary to properly position and focus the pump beam through lenses and optics
Solution Approach 2:
Instead of using optics to focus the divergent pump beam, the patent inverts the approach by allowing the divergence to naturally illuminate the gain medium, turning what was previously a problem (divergence) into the solution
3Temperature
If pump source is positioned at a distance from gain medium, then heat management is improved, but pumping efficiency decreases due to divergence
Solution Approach 1:
The pump source is nested or closely coupled to the gain medium, with the pump source positioned within 2mm (preferably within 1mm or 0.2mm) of the gain medium surface, allowing direct illumination while managing heat through the compact integrated design
Solution Approach 2:
The patent changes the spatial parameter by positioning the pump source extremely close to the gain medium (within 2mm, preferably within 1mm or 0.2mm), which maintains high pumping efficiency despite the close proximity by using the natural divergence of the pump source
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 design results in a more compact, robust, and cost-effective side pumped laser with improved pumping efficiency and uniform output, eliminating the need for additional optics and minimizing light loss.
Implementation Method 1
radiation from the pump source is directly incident on the gain medium, i.e. the light from the pump source may be incident on the gain medium without passing through other optical components
Implementation Method 2
using a reflective coating on the gain medium to optimize radiation distribution
Data Source
AI summary
A side pumped laser comprises an elongated gain medium (10) provided between an output coupler (20) and a counter reflector (15) and a pump source (65) configured to provide radiation to the gain medium (10) along a side axis of the gain medium, wherein the laser is configured such that radiation from the pump source is directly incident on the gain medium; and the pump source is provided proximate, adjacent or in contact with the gain medium. The laser material and compositions, geometries and dimensions are designed to both maximize laser performance and to permit the use of construction techniques commonplace in the production of equipment designed for optical telecoms systems to facilitate low cost high volume and miniaturization. The elongated gain medium (10) may have a polygonal cross-section with a non-coated side surface (55) receiving pump light emitted by a laser diode bar (65) while the other, non-emitting surfaces are coated with for example a gold coating (60) for pump light recycling and cooling of the gain medium by heat conduction. The counter reflector (15) may be provided on one facet of a passive Q-switch (30) and the output coupler (20) on a facet (50b) of the gain medium (10).