Semiconductor Light Emitting Element Removing Zero-Order Light Noise
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Solution Overview
Problem
Conventional semiconductor light emitting elements, particularly S-iPM lasers, suffer from the issue of outputting zero-order light alongside the desired optical image, which acts as noise and is not utilized, making it necessary to develop a structure that can effectively remove zero-order light to enhance image quality.
Innovation Solution
A semiconductor light emitting element with a phase modulation layer and distributed Bragg reflector layers is designed such that the phase modulation layer's modified refractive index regions are positioned off-center within a virtual square lattice, and the distributed Bragg reflector layers are strategically placed to reflect zero-order light, allowing only the desired optical image to be emitted.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional S-iPM laser structure is used, then the desired optical image can be output along with zero-order light, but the zero-order light acts as noise and reduces image quality
Solution Approach 1:
The patent extracts and removes the zero-order light component from the output beam by introducing a spatial filter or aperture that blocks the central zero-order beam while allowing the desired first-order diffracted beams to pass through, thereby eliminating the noise source while preserving the useful optical image
Solution Approach 2:
The patent introduces an intermediary optical element (such as a spatial filter, aperture, or beam blocking structure) positioned at the focal plane of a lens to selectively block the zero-order light while transmitting the diffracted beams that carry the optical image information
2Device complexity
If the phase modulation layer uses a standard square lattice with centered modified refractive index regions, then the structure is simple, but zero-order light cannot be removed
Solution Approach 1:
The patent introduces asymmetry into the phase modulation layer by shifting the modified refractive index regions from the center of each lattice unit to an offset position, which disrupts the symmetry that generates strong zero-order diffraction and thereby suppresses the zero-order light output
Solution Approach 2:
The patent modifies the local structure within each lattice unit by creating an asymmetric distribution of the modified refractive index regions, where the position and shape of these regions are specifically designed to control the diffraction pattern and minimize zero-order light generation
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 successfully removes zero-order light from the output, improving the signal-to-noise ratio and enabling the formation of arbitrary optical images with enhanced clarity and precision.
Implementation Method 1
a distributed Bragg reflector layer which has a transmission characteristic with respect to a specific optical image outputted along an inclined direction and has a reflection characteristic with respect to zero-order light outputted along a normal direction
Implementation Method 2
The phase modulation layer has a base layer and a plurality of modified refractive index regions each of which has a refractive index different from a refractive index of the base layer
Data Source
AI summary
The present embodiment relates to a semiconductor light emitting element having a structure that enables removal of zero-order light from output light of an S-iPM laser. The semiconductor light emitting element includes an active layer, a pair of cladding layers, and a phase modulation layer. The phase modulation layer has a base layer and a plurality of modified refractive index regions each of which is individually arranged at a specific position. One of the pair of cladding layers includes a distributed Bragg reflector layer which has a transmission characteristic with respect to a specific optical image outputted along an inclined direction with respect to a light emission surface and has a reflection characteristic with respect to the zero-order light outputted along a normal direction of the light emission surface.