Monolithic Frequency-Doubled Light Source With Integrated SHG Optics
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Solution Overview
Problem
Current semiconductor light emitting devices face challenges in efficiently converting infrared light into visible light for applications like display systems and sensor systems, where high brightness, resolution, and efficiency are required, but achieving this conversion with high power and small size is difficult.
Innovation Solution
A semiconductor light emitting device with an active region emitting infrared light and a planar optical component, such as a micro-lens or gradient refractive index lens, focuses the infrared light into a second harmonic generation crystal, which converts it into visible light, using a selective reflection layer to form an external cavity and enhance the conversion efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a semiconductor light emitting device uses infrared emission with second harmonic generation to achieve visible light conversion, then the brightness and efficiency are improved, but the device size and complexity increase
Solution Approach 1:
The patent combines the infrared light source, planar optical component, and SHG crystal into a single integrated monolithic device structure. This merging of previously separate components (infrared LED/micro-LED, lens, and nonlinear crystal) into one compact unit achieves high brightness visible light conversion while minimizing device size, as the components work together in a unified integrated architecture rather than requiring separate assemblies.
Solution Approach 2:
The planar optical component is formed within or integrated into the semiconductor layers of the light emitting device, creating a nested structure where the optical element is embedded within the semiconductor device architecture. This nesting allows the optical focusing function to be achieved without adding external bulk, maintaining compact device size while enabling efficient infrared-to-visible light conversion through the SHG crystal.
2Productivity
If a planar optical component is added to focus infrared light into the SHG crystal, then the conversion efficiency is improved, but the device complexity increases
Solution Approach 1:
The planar optical component is merged with the semiconductor light emitting device structure, forming an integrated unit where the optical element and light source share a common substrate and fabrication process. This combination achieves efficient infrared light focusing into the SHG crystal while avoiding the complexity of assembling separate optical components, as everything is formed through integrated semiconductor processing techniques.
Solution Approach 2:
The patent replaces traditional mechanical or separate optical focusing systems with a planar optical component formed through semiconductor processing. Instead of using bulky external lenses or complex mechanical focusing mechanisms, the optical function is achieved through planar structures fabricated using standard semiconductor manufacturing techniques, thereby improving conversion efficiency while reducing device complexity.
3Manufacturing precision
If multiple semiconductor layers with different refractive indices are used to form the planar lens, then the focusing capability is improved, but the manufacturing complexity increases
Solution Approach 1:
The patent utilizes changes in refractive index parameters across different semiconductor layers to create the planar lens functionality. By varying the composition or structure of semiconductor layers to achieve different refractive indices, the focusing capability is improved without requiring complex external optical components. This parameter change approach allows precise control of light focusing while using standard semiconductor materials and fabrication processes.
Solution Approach 2:
The planar optical component is formed with spatially varying properties within the semiconductor layers, where different regions have different refractive indices tailored to achieve the desired focusing function. This local quality variation is achieved through selective oxidation or etching of specific semiconductor layers in specific regions, allowing precise focusing control while using conventional semiconductor manufacturing techniques rather than complex external optics.
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 approach enables the efficient conversion of infrared light to visible light, improving the brightness and resolution of display systems and sensor applications by achieving high power and small size, while maintaining low power consumption.
Implementation Method 1
a planar optical component that focuses the light in the longer wavelength into a second harmonic generation (SHG) crystal, which may then convert the light in the longer wavelength into light having a shorter wavelength
Implementation Method 2
The planar optical component may include, for example, a micro-lens formed in semiconductor layers or a gradient refractive index (GRIN) lens formed in the SHG crystal
Data Source
AI summary
A semiconductor light source including a planar optical component that focuses long-wavelength (e.g., infrared) light emitted in a resonant cavity into a nonlinear crystal, which then converts the long-wavelength light into light having a shorter wavelength (e.g., visible light) by frequency doubling. A wavelength-selective reflection layer on the nonlinear crystal reflects the long-wavelength light back into the resonant cavity to form an external cavity and transmits the light having the shorter wavelength out of the external cavity. The resonant cavity includes an active region that emits the long-wavelength light at a high efficiency. The planar optical component includes a micro-lens formed in semiconductor layers or a gradient refractive index lens formed in the nonlinear crystal.