Stacked Semiconductor Laser Active Zones for Compact Projectors
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Solution Overview
Problem
Existing light sources for projectors and vehicle headlights face limitations in luminance and beam shaping due to the need for complex optics and inefficient wavelength conversion using phosphors, which are bulky and inefficient, especially in compact applications.
Innovation Solution
A compact semiconductor laser arrangement with multiple electrically pumped active zones emitting different wavelengths, guided by a semiconductor waveguide structure, allowing for direct coupling and efficient emission of colored light without phosphors, enabling tunable color and high luminance with reduced optical complexity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If phosphor-based wavelength conversion is used, then white light can be generated from blue laser, but the device becomes bulky and beam shaping capability is lost
Solution Approach 1:
The invention segments the single blue laser source into multiple active zones within the laser chip itself, with each zone emitting at a different wavelength (blue, cyan, green, yellow-green, red). This eliminates the need for external phosphor conversion components and complex optical systems, directly resolving the contradiction between achieving full-spectrum light and maintaining device compactness.
Solution Approach 2:
The invention extracts the wavelength conversion function from external phosphor materials and integrates it directly into the laser chip's active zones. By generating different wavelengths directly at the light source rather than converting them externally, the patent eliminates bulky phosphor components and maintains beam shaping capability.
2Adaptability or versatility
If multiple semiconductor laser chips are arranged laterally next to each other, then different wavelengths can be emitted, but the radiation from one light source passes through other light sources causing absorption
Solution Approach 1:
The invention transitions from lateral arrangement of multiple chips to a vertical stacking arrangement where multiple active zones are positioned one above another along the growth direction. This dimensional change allows radiation from upper active zones to pass through lower ones without significant absorption, as the beam path through absorbing materials is minimized.
Solution Approach 2:
The invention arranges active zones with specific material compositions at different positions along the growth direction, with each zone optimized for its specific wavelength emission. The material composition and band gap are locally tailored so that radiation from each zone passes through other zones with minimal absorption, as each zone's material is transparent to wavelengths emitted by other zones.
3Adaptability or versatility
If active zones with different material compositions are stacked, then different wavelengths can be emitted, but radiation from preceding active zones may be absorbed in downstream active zones
Solution Approach 1:
Each active zone is designed with specific local material properties (AlInGaN composition ratios) optimized for its emission wavelength, while being transparent to wavelengths from other zones. This local optimization of material composition ensures that radiation from preceding zones passes through downstream zones without significant absorption.
Solution Approach 2:
The invention changes the material composition parameters (Al content, In content, Ga content) of each active zone to achieve different emission wavelengths while maintaining transparency to other wavelengths. By carefully controlling these compositional parameters, the patent minimizes absorption losses between stacked active zones.
4Volume of moving object
If a single waveguide structure guides radiation from all active zones, then the device remains compact, but the waveguide must be traversed by all radiations jointly
Solution Approach 1:
The invention designs a single waveguide structure that serves multiple functions by guiding radiation from all stacked active zones simultaneously. This universal waveguide approach maintains device compactness while handling multiple wavelengths through a unified optical path.
Solution Approach 2:
The waveguide structure uses homogeneous material composition (AlInGaN) throughout, which provides consistent optical properties for guiding different wavelengths. This homogeneity simplifies the waveguide design while enabling it to efficiently guide radiation from all active zones with different material compositions.
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 semiconductor laser arrangement achieves efficient, tunable, and directed emission of colored light, overcoming the limitations of traditional light sources by eliminating the need for complex optics and phosphor-based wavelength conversion, resulting in a compact, high-luminance, and beam-shaped light source.
Implementation Method 1
The waveguide structure is based on the principle of total reflection
Implementation Method 2
The laser radiation is generated by recombination of charge carriers in at least one semiconductor material of the active zones
Data Source
AI summary
A semiconductor laser arrangement and a projector are disclosed. In an embodiment the semiconductor laser arrangement includes at least two electrically pumped active zones, each active zone configured to emit laser radiation of a different emission wavelength and a semiconductor-based waveguide structure, wherein the active zones are electrically independently operable of one another, wherein the active zones optically follow directly one another along a beam direction and are arranged in a descending manner with regard to their emission wavelengths, wherein at least in a region of a last active zone along the beam direction, a laser radiation of all active zones jointly runs through the waveguide structure, wherein at least the last active zone comprises a plurality of waveguides which are stacked one above the other and are oriented parallel to one another, wherein one of the waveguides is configured for the radiation emitted by the last active zone.