Flared Laser Waveguide for Brightness and Power
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional broad area semiconductor diode lasers face challenges in scaling power while maintaining superior brightness, particularly due to multimode behavior across the slow axis, which limits their efficiency and output power.
Innovation Solution
The introduction of a flared laser oscillator waveguide with a flared current injection region between a high reflector facet and a partial reflector facet, which narrows the electrically-pumped stripe towards the high reflector facet, preventing higher order modes from coupling back into the laser and reducing thermal and electrical resistance, thereby enhancing beam quality and output power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the emitter width is reduced to improve brightness, then brightness is improved, but the maximum output power drops
Solution Approach 1:
The patent introduces a flared waveguide structure that varies the waveguide width along the propagation direction, transitioning from a narrow input waveguide to a wider output waveguide. This dimensional variation allows the device to achieve both high brightness (narrow effective emission area) and high output power (large total emission area) simultaneously by utilizing the third dimension (propagation direction) to reconcile the conflicting requirements.
2Power
If the stripe width is increased to achieve higher output power, then output power increases, but multimode behavior degrades beam quality
Solution Approach 1:
The flared waveguide can be viewed as a series of incremental width segments along the propagation direction. Each segment gradually increases the waveguide width, allowing mode evolution and filtering. This segmentation approach enables the waveguide to support high power through increased total area while maintaining beam quality by progressively managing mode content through the flared structure.
3Illumination intensity
If a narrower waveguide is used to maintain single-mode operation, then beam quality is maintained, but output power is limited
Solution Approach 1:
The waveguide width is made dynamic rather than static, varying continuously along the propagation direction. The waveguide starts narrow to support single-mode operation and gradually flares to a wider output to increase power capacity. This dynamic geometry allows the device to adapt its mode content and power handling capability along the propagation direction, achieving both high beam quality and high output power.
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 smaller beam parameter product (BPP) and higher brightness across the slow-axis, enabling higher output power with improved electrical-to-optical power conversion efficiency and reduced thermal resistance, surpassing conventional broad area laser diodes in performance.
Implementation Method 1
The active layer (quantum well(s), quantum wire(s) or quantum dots, type-II quantum well(s)) resides in the waveguide layer which has a higher index of refraction compared to the surrounding p- and n-doped cladding layers. Light generated from the active layer is confined in the plane of the waveguide.
Implementation Method 2
A typical semiconductor laser comprises n-type layers, p-type layers and an undoped active layer between them such that when the diode is forward-biased, electrons and holes recombine in the active region layer to produce light.
Data Source
AI summary
A high brightness diode laser package includes a plurality of flared laser oscillator waveguides arranged on a stepped surface to emit respective laser beams in one or more emission directions, a plurality of optical components situated to receive the laser beams from the plurality of flared laser oscillator waveguides and to provide the beams in a closely packed relationship, and an optical fiber optically coupled to the closely packed beams for coupling the laser beams out of the diode laser package.