Semiconductor Frequency Conversion via Multiphoton Absorption
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Solution Overview
Problem
Current semiconductor laser diodes face limitations in generating laser radiation across a wider wavelength range due to dominant series resistance and immature characteristics, particularly in the 400 nm to 480 nm range, and existing frequency conversion methods are complex and not suitable for short-wave generation.
Innovation Solution
An edge-emitting semiconductor component with a pump laser diode, where optical pump radiation is absorbed by multiphoton absorption in the active zone, generating shorter wavelength radiation through a resonant cavity with specifically designed facets and gratings, allowing flexible waveguide design and efficient frequency conversion without external resonators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional semiconductor laser diodes are used in the 400 nm to 480 nm wavelength range, then laser radiation can be generated, but the beam quality is restricted due to dominant series resistance from low p-conductivity
Solution Approach 1:
The device is segmented into distinct functional regions: a pump laser diode for generating pump radiation, a frequency conversion component for wavelength transformation, and a resonator system. This segmentation allows each component to be independently optimized, enabling high beam quality in the frequency conversion component without being constrained by the electrical properties of the pump source.
Solution Approach 2:
The patent introduces an intermediary frequency conversion component (nonlinear optical crystal or semiconductor structure) that converts pump radiation at one wavelength to laser radiation at a different wavelength. This intermediary allows the system to bypass the electrical conductivity limitations by using optical pumping rather than direct electrical injection in the active laser medium.
2Adaptability or versatility
If frequency doubling is used to generate wavelengths not directly accessible, then more wavelengths can be accessed, but the system becomes more complex requiring external resonators and optical couplers
Solution Approach 1:
The patent merges the frequency conversion component with the resonator to form an integrated cavity system. The nonlinear optical layer is positioned inside the resonator formed by the pump laser diode facets, eliminating the need for external resonators and optical couplers. This integration maintains wavelength versatility while significantly reducing system complexity.
Solution Approach 2:
The pump laser diode facets serve multiple functions: they act as both the pump radiation source and the resonator mirrors. This multi-functionality eliminates the need for separate external resonator components, simplifying the overall system structure while maintaining the ability to generate multiple wavelengths through frequency conversion.
3Productivity
If pump laser diode and frequency-converting component are monolithically integrated, then efficiency increases, but individual optimization becomes difficult
Solution Approach 1:
While the pump laser diode and frequency conversion component are integrated in space, they remain distinct functional segments that can be independently designed and optimized. The pump diode can be optimized for its wavelength and power characteristics, while the frequency conversion component can be independently optimized for its nonlinear optical properties, allowing both to achieve their optimal performance simultaneously.
4Shape
If vertically emitting laser structure is used, then beam shape is determined by external resonator, but radiation extraction is limited to upward direction through small diameter
Solution Approach 1:
Instead of extracting radiation vertically upward through a small diameter as in conventional vertically emitting lasers, the patent inverts the extraction geometry by using the lateral facets of the pump laser diode as emission and resonator surfaces. This allows radiation extraction in the lateral direction through much larger effective areas, significantly increasing productivity while maintaining beam shape control through the resonator configuration.
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
Enables the generation of laser radiation across a broader wavelength range from 630 nm to 220 nm with improved beam quality and power stability, reducing the need for precise temperature control and allowing for more flexible design of waveguides and beam shapes.
Implementation Method 1
the active zone having a cavity, wherein the cavity has a resonant frequency which causes a resonance increase of the optical radiation
Implementation Method 2
the entrance facet having a reflectivity for the pump radiation of less than 0.1 and a reflectivity for the optical radiation greater than 0.7
Data Source
AI summary
The component (200) has semiconductor layers epitaxially formed onto a semiconductor substrate layer (201) and comprising an active zone (203) and a waveguide layer (202). An entrance facet and an exit facet are laterally located with respect to the zone. The zone is designed to absorb pumped optical radiation of a wavelength by multi-photon absorption and to generate an optical radiation of another wavelength that is shorter than the former wavelength. The zone comprises a quantum well (205) surrounded by barriers (206), which have a wider band gap than that of the quantum well. Independent claims are also included for the following: (1) a frequency conversion system (2) a method for operating a semiconductor component (3) a method for manufacturing a semiconductor component.