Laser Diode Subassembly Using Dichroic Reflector Array
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Solution Overview
Problem
Laser diode light sources face issues with bulkiness and increased cost due to the need for multiple wavelength-selective external volume Bragg reflectors and dichroic mirrors, which restrict close placement and scalability.
Innovation Solution
The use of an array of laser diode emitters and dichroic reflectors with sequential array indices, where each reflector redirects sub-beams to form a combined optical beam, allowing for a common partial reflector to replace individual wavelength-selective reflectors, enabling compact placement and efficient light combination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If multiple wavelength-selective external volume Bragg reflectors and dichroic mirrors are used to combine laser beams at different wavelengths, then the brightness and power density of the output laser beam is improved, but the device becomes bulkier and more expensive
Solution Approach 1:
The patent merges multiple wavelength-selective reflectors into a single integrated volume Bragg grating that can selectively reflect multiple wavelengths simultaneously. This consolidation reduces the number of separate optical components (dichroic mirrors and individual VBGs) needed in the system, thereby reducing device complexity and bulkiness while maintaining the ability to combine laser beams at different wavelengths effectively
Solution Approach 2:
The invention makes a single volume Bragg grating perform multiple functions by designing it to reflect multiple different wavelengths of light simultaneously. This multi-functional approach replaces what would traditionally require multiple separate wavelength-selective reflectors, reducing the overall number of components needed and simplifying the optical system architecture
2Adaptability or versatility
If multiple wavelength-selective external volume Bragg reflectors are used for each laser diode emitter, then the laser beam combination at different wavelengths is improved, but the cost of the laser diode light source increases
Solution Approach 1:
The patent combines the functionality of multiple individual wavelength-selective VBGs into a single multi-wavelength VBG component. This merging reduces the total number of precision optical components that need to be manufactured and assembled, thereby lowering manufacturing costs while preserving the wavelength-selective beam combination capability across multiple laser diode emitters
3Measurement precision
If dichroic mirrors are placed at small angles of incidence (12-25 degrees) to reflect light in wavelength-selective manner, then the wavelength selectivity is improved, but the placement distance between mirrors increases, making the device bulkier
Solution Approach 1:
The patent changes the operational parameters of the volume Bragg grating by designing it to operate at larger angles of incidence (45±10 degrees) compared to traditional dichroic mirrors (12-25 degrees). This parameter change allows for more compact positioning of optical components while maintaining effective wavelength-selective reflection through the engineered diffraction properties of the VBG structure
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 configuration allows for compact and cost-effective laser diode assemblies with improved scalability, maintaining high brightness and efficiency by using a common partial reflector to form a laser cavity for each emitter, while reducing the number of required reflectors.
Implementation Method 1
Each reflector may have a sequential array index. An array of laser diode emitters may be provided. Each emitter may have a sequential array index from 1 to M in the array of M laser diode emitters. The array indices are assigned in the present disclosure for explanation and identification purposes... Individual reflectors of the array redirect laser sub-beams from individual laser diode emitters having same array indices, to propagate via dichroic reflectors having higher array indices, if any, so as to form a combined optical beam.
Implementation Method 2
a partial reflector disposed downstream of the array of M dichroic reflectors in an optical path of the optical beam and arranged to reflect a portion of each light sub-beam comprising the optical beam to propagate back to its originating laser diode emitter, thereby forming a laser cavity for each one of the M laser diode emitters
Data Source
AI summary
A laser diode subassembly is disclosed, in which dichroic reflectors are disposed sequentially one after another forming an array or stack, each reflector having a sequential array index. An array of laser diode emitters is provided, each emitter having a sequential array index. Individual reflectors of the array redirect laser sub-beams from individual laser diode emitters having same array indices, to propagate via dichroic reflectors having higher array indices, so as to form a combined optical beam. A common partial reflector may be used for the laser diode emitters instead of individual wavelength selective reflectors for each laser diode emitter.