Semiconductor Laser Diode With Monolithic Dual Resonators
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Solution Overview
Problem
Semiconductor laser diodes face challenges in achieving high optical output power with good beam quality, as broad resonator structures lead to inhomogeneous mode distributions and facet instability, while high optical power diodes have insufficient beam quality due to inhomogeneities in index-guided and gain-guided laser structures.
Innovation Solution
A semiconductor laser diode design featuring two monolithically integrated resonators, where one resonator is electrically pumped to generate a pump beam that optically pumps the second resonator, improving beam quality by reducing the laser threshold and suppressing unwanted emission, and allowing for a compact, high-quality beam source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If broad laser resonator structures are used to achieve high optical output powers, then optical power is improved, but beam quality deteriorates due to inhomogeneous mode distributions and filamentations
Solution Approach 1:
The patent divides the single resonator into multiple resonators (first resonator and second resonator) with different resonator directions. The first resonator generates laser light in a first direction, and the second resonator generates laser light in a second direction perpendicular to the first. This segmentation allows each resonator to operate with narrower aperture requirements, maintaining beam quality while achieving high total optical power through combined output.
2Power
If broad laser resonator structures are used to achieve high optical output powers, then optical power is improved, but facet stability deteriorates due to inhomogeneous intensity distributions and hot spots
Solution Approach 1:
By segmenting the laser structure into multiple resonators with perpendicular resonator directions, the patent distributes the optical power generation across separate active regions. This prevents the formation of concentrated hot spots on any single facet, as each resonator's narrower aperture creates more uniform intensity distributions, thereby improving facet stability and reliability.
3Device complexity
If index-guided and gain-guided laser structures are used, then device integration is improved, but beam quality deteriorates due to inhomogeneities in horizontal wave guidance
Solution Approach 1:
The patent transitions from horizontal wave guidance (which suffers from inhomogeneities in index-guided and gain-guided structures) to vertical cavity resonators where light propagation occurs in the vertical direction. This dimensional change eliminates the horizontal guidance inhomogeneity problem while maintaining monolithic integration, as the resonators are formed within the semiconductor layer structure grown in the vertical direction.
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 achieves high beam quality and reduced laser threshold, enabling efficient coupling of pump radiation while preventing undesired emission, thus overcoming the limitations of traditional semiconductor laser diodes.
Implementation Method 1
Each of the resonators has a laser-active material, i.e., a material that is suitable for generating laser light by stimulated emission
Implementation Method 2
The laser-active material of each of the resonators is arranged between respective resonator mirrors
Implementation Method 3
The resonators are optically coupled so that light from at least one of the resonators can be coupled into another of the resonators, where it can excite the laser-active material to generate light
Data Source
AI summary
A semiconductor laser diode is disclosed. In an embodiment a semiconductor laser diode includes a first resonator and a second resonator, the first and second resonators having parallel resonator directions along a longitudinal direction and being monolithically integrated into the semiconductor laser diode, wherein the first resonator includes at least a part of a semiconductor layer sequence having an active layer and an active region configured to be electrically pumped to generate a first light, wherein the longitudinal direction is parallel to a main extension plane of the active layer, and wherein the second resonator has an active region with a laser-active material configured to be optically pumped by at least a part of the first light to produce a second light which is partially emitted outwards from the second resonator.