Multiple Flared Laser Waveguide for Brightness and Power Scaling
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Solution Overview
Problem
Conventional semiconductor diode lasers face challenges in scaling output power while maintaining high brightness, particularly due to multimode behavior across the slow axis, which limits their efficiency and power conversion capabilities.
Innovation Solution
The implementation of a multiple flared oscillator waveguide design with component flared waveguides having a high reflector facet and a partial reflector facet, where the partial reflector facet is wider than the high reflector facet, and the current injection region is flared to prevent higher order modes from coupling back into the laser, resulting in improved beam quality and increased power conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the emitter width is reduced to improve brightness, then the slow-axis brightness improves, but the maximum output power drops
Solution Approach 1:
The patent divides the laser emitter into multiple separate emitters (e.g., three emitters) arranged in an array. Each emitter has a narrow width that supports only fundamental mode operation, ensuring high brightness. By combining multiple emitters, the total output power increases while each individual emitter maintains diffraction-limited beam quality. This segmentation resolves the contradiction by allowing brightness optimization at the individual emitter level while achieving power scaling through multiplication of emitters.
2Power
If the stripe width is increased to scale power, then the output power increases, but the beam quality degrades due to multimode behavior
Solution Approach 1:
Instead of using a single wide stripe that supports multiple modes, the patent segments the wide emission region into multiple narrow stripes, each supporting only the fundamental mode. This allows the overall device to achieve high power output equivalent to a wide stripe while maintaining the beam quality of narrow single-mode emitters. The segmented approach prevents higher-order modes from forming while still providing large total pumped area.
Solution Approach 2:
The patent transitions from a single-dimensional wide stripe geometry to a multi-emitter array geometry. By arranging multiple narrow emitters in an array configuration (e.g., lateral or vertical arrangement), the system achieves power scaling in a different dimensional configuration rather than simply expanding the stripe width. This dimensional change allows power scaling without the detrimental multimode effects that occur in wide single-stripe geometries.
3Illumination intensity
If a single-mode ridge waveguide is used to improve beam quality, then the beam quality improves, but the output power is limited
Solution Approach 1:
The patent applies segmentation by using multiple independent single-mode ridge waveguides (emitters) rather than a single wide multimode waveguide. Each ridge waveguide maintains single-mode operation for high beam quality, while the array of multiple ridges provides the power scaling capability. This resolves the contradiction by combining the beam quality advantage of single-mode operation with the power advantage of multiple emitters working in parallel.
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 higher output power with reduced beam parameter product (BPP) and enhanced slow-axis brightness, enabling power scaling without compromising beam quality, and allows for larger total pumped areas with lower thermal and electrical resistance.
Implementation Method 1
Opposing end facets of the waveguide define high and partial reflectors to provide feedback for oscillation of light within the resonator
Implementation Method 2
a flared current injection region extending and widening between the multimode high reflector facet and the partial reflector facet
Implementation Method 3
The active layer 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.
Data Source
AI summary
A broad area semiconductor diode laser device includes a multiple flared oscillator waveguide including a plurality of component flared oscillator waveguides, each component flared oscillator waveguide including a multimode high reflector facet, a partial reflector facet spaced apart from the high reflector facet, and a flared current injection region extending and widening between the multimode high reflector facet and the partial reflector facet, wherein the ratio of a partial reflector facet width to a high reflector facet width is n:1, where n>1, and wherein the component flared oscillator waveguides of the multiple flared oscillator waveguide are arranged in a row such that portions of the flared current injection regions of adjacently situated component flared oscillator waveguides overlap each other or are in proximity to each other on the order of the wavelength of light emitted by the component flared oscillator waveguides.