Phase-Modulated S-iPM Laser Layout for Zero-Order Light Removal
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Solution Overview
Problem
S-iPM lasers output unwanted zero-order light, which can cause intensity unevenness and noise, and it is desirable to remove this light to obtain a clear optical image.
Innovation Solution
A light emission device with a phase modulation layer having modified refractive index regions arranged in a two-dimensional shape, where the center of gravity of each region is separated from the lattice points and a rotation angle is set according to a phase distribution, satisfying the M-point oscillation condition to suppress zero-order light output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If Γ-point oscillation is used in S-iPM laser, then the laser can output signal light forming optical images, but zero-order light is also outputted in the normal direction causing intensity unevenness and noise
Solution Approach 1:
The patent converts the harmful zero-order light into a beneficial element by using it as a reference beam for interference measurement. The phase modulation layer is designed to output both zero-order light and signal light, and the system utilizes the interference between these two beams to measure surface shapes with high precision, transforming the previously harmful zero-order light into a useful measurement reference
Solution Approach 2:
The patent introduces an intermediary measurement system that separates the functions of signal light (optical image formation) and zero-order light (reference beam). By using the zero-order light as an intermediary reference beam that interferes with the signal light, the system can extract surface shape information while the signal light continues to form optical images, thus resolving the contradiction between signal light output and zero-order light noise
2Object-generated harmful factors
If zero-order light is removed from optical image, then noise is reduced, but additional optical components or complex structures are required
Solution Approach 1:
The phase modulation layer is designed to serve multiple functions simultaneously: it modulates the phase of signal light to form optical images, outputs zero-order light as a reference beam for interference measurement, and enables surface shape measurement through interference between the two beams. This multi-functionality eliminates the need for separate components to remove or manage zero-order light, reducing overall system complexity while achieving noise reduction
3Object-generated harmful factors
If M-point oscillation condition is satisfied with specific wavenumber vectors, then zero-order light is suppressed, but the oscillation condition becomes more restrictive
Solution Approach 1:
The patent changes the oscillation condition parameter from Γ-point to M-point in the reciprocal lattice space, and specifically selects wavenumber vectors with magnitudes smaller than 2π/λ. This parameter change suppresses zero-order light output while the patent demonstrates that multiple wavenumber vector configurations can satisfy this condition, providing flexibility in system design
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 solution effectively removes zero-order light from the output of the S-iPM laser, ensuring only signal light is outputted, thereby improving the clarity and quality of the optical image.
Implementation Method 1
a phase modulation layer optically coupled to an active layer. The phase modulation layer includes a base layer and a plurality of modified refractive index regions having a refractive index different from a refractive index of the base layer
Implementation Method 2
The phase modulation layer includes a base layer and a plurality of modified refractive index regions having a refractive index different from a refractive index of the base layer
Implementation Method 3
Semiconductor light emission elements that form any optical image by controlling a phase distribution and an intensity distribution of light outputted from a plurality of light emission points
Data Source
AI summary
The present embodiment relates to a light emission device capable of removing zero-order light from output light of an S-iPM laser. The light emission device comprises an active layer and a phase modulation layer. The phase modulation layer includes a base layer and a plurality of modified refractive index regions. In a state in which a virtual square lattice is set on the phase modulation layer, a center of gravity of each modified refractive index region is separated from a corresponding lattice point, and a rotation angle around each lattice point that decides a position of the center of gravity of each modified refractive index region is set according to a phase distribution for forming an optical image. A lattice spacing and an emission wavelength satisfy a condition of M-point oscillation in a reciprocal lattice space of the phase modulation layer. A magnitude of at least one of in-plane wavenumber vectors in four directions formed in the reciprocal lattice space and each including a wavenumber spread corresponding to an angle spread of the output light is smaller than 2π/λ.