Phase Modulation Layer Layout for Zero-Order Light Suppression
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Solution Overview
Problem
Conventional S-iPM lasers output zero-order light in addition to signal light, which acts as noise and is undesirable for desired optical images, necessitating a solution to reduce zero-order light in the output.
Innovation Solution
A light emission device with a phase modulation layer having modified refractive index regions arranged on an imaginary square lattice, where the centers of gravity of these regions are strategically positioned to minimize zero-order light output by optimizing the distance and angle from lattice points, allowing light to form optical images along the normal and inclined directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional S-iPM laser structure is used, then arbitrary optical images can be formed, but zero-order light is generated as noise
Solution Approach 1:
The patent applies asymmetry by intentionally shifting the center of gravity of the modified refractive index region from the lattice point position. This asymmetric arrangement (distance greater than 0.30 times lattice spacing) disrupts the symmetry that generates zero-order light, thereby suppressing the noise while preserving the ability to form arbitrary optical images through controlled phase modulation.
Solution Approach 2:
The patent changes the positional parameter of the modified refractive index region relative to the lattice point. By adjusting the distance parameter to be greater than 0.30 times the lattice spacing, the phase modulation characteristics are optimized to reduce zero-order light intensity while maintaining effective optical image formation capability.
2Measurement precision
If zero-order light is removed from output, then signal-to-noise ratio improves, but light emission efficiency may be affected
Solution Approach 1:
The patent applies local quality by creating a modified refractive index region with specific properties at a specific location (shifted from lattice point). This localized phase modulation structure selectively suppresses zero-order light in certain directions while maintaining efficient light emission in other directions, thus improving signal-to-noise ratio without significantly compromising overall light emission efficiency.
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 reduces zero-order light in S-iPM lasers, enhancing the signal-to-noise ratio of the output beam pattern and enabling the formation of arbitrary optical images along desired directions.
Implementation Method 1
the phase modulation layer has a base layer and a plurality of modified refractive index regions each having a refractive index different from the refractive index of the base layer
Data Source
AI summary
A light emission device of one embodiment reduces zero-order light included in output of an S-iPM laser. The light emission device includes a light emission unit and a phase modulation layer. The phase modulation layer has a base layer and modified refractive index regions each including modified refractive index elements. In each unit constituent region centered on a lattice point of an imaginary square lattice set on the phase modulation layer, the distance from the corresponding lattice point to each of the centers of gravity of the modified refractive index elements is greater than 0.30 times and is not greater than 0.50 times of the lattice spacing. In addition, the distance from the corresponding lattice point to the center of gravity of the modified refractive index elements as a whole is greater than 0 and is not greater than 0.30 times of the lattice spacing.