Semiconductor Laser Wave Front Control via Spatial Light Modulator
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Solution Overview
Problem
Conventional semiconductor laser devices lack the capability for wave front control, preventing the formation of intended variable laser beam patterns through phase control of each minute region.
Innovation Solution
A semiconductor laser device incorporating a semiconductor laser chip with a diffraction grating layer and a spatial light modulator, where the spatial light modulator includes a common electrode, pixel electrodes, and a liquid crystal layer to modulate the phase of the laser beam by varying the refractive index with applied voltage, enabling wave front control and formation of variable laser beam patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional semiconductor laser device is used, then the device structure is simple, but wave front control capability is lacking
Solution Approach 1:
The patent merges the semiconductor laser chip with a spatial light modulator into a single integrated device. The spatial light modulator is directly coupled to the laser chip, allowing phase modulation of the laser beam without requiring separate external modulation systems. This combination provides wave front control capability while maintaining a compact integrated structure.
Solution Approach 2:
The patent introduces a spatial light modulator as an intermediary component between the laser source and the output. This modulator acts as a mediator that controls the phase of light waves by applying voltage to pixel electrodes, thereby enabling wave front control without fundamentally changing the laser chip structure.
2Adaptability or versatility
If phase control of each minute region is not implemented, then the device structure is simple, but formation of intended variable laser beam patterns is not possible
Solution Approach 1:
The spatial light modulator is divided into multiple pixel electrodes, each corresponding to a minute region of the laser beam cross-section. By independently controlling the voltage applied to each pixel electrode, the patent enables phase control of specific regions, allowing formation of various laser beam patterns such as annular beams or focused spots.
Solution Approach 2:
The patent applies different voltages to different pixel electrodes to create local phase variations across the laser beam cross-section. This local quality control allows specific regions of the beam to be modulated differently, enabling precise control of beam patterns and wave front shaping.
3Ease of operation
If a spatial light modulator is added to the semiconductor laser chip, then wave front control is enabled, but device complexity increases
Solution Approach 1:
The spatial light modulator serves multiple functions: it acts as a phase modulator, a beam shaper, and a wave front controller simultaneously. By using this single component, the patent eliminates the need for separate optical elements for each function, thereby reducing overall device complexity while maintaining high ease of operation for wave front control.
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 formation of intended variable laser beam patterns by modulating the phase of each minute region, allowing for precise superimposition of wave fronts and improved image formation capabilities.
Implementation Method 1
a permittivity (refractive index) of the liquid crystal layer varies depending on voltage applied to the pixel electrode. Thus, an optical path length of the liquid crystal layer with respect to the laser beam varies and a phase varies.
Implementation Method 2
a diffraction grating layer which is optically connected to the active layer, and the spatial light modulator includes a common electrode, a plurality of pixel electrodes, and a liquid crystal layer arranged between the common electrode and the pixel electrodes
Data Source
AI summary
This semiconductor laser device includes a semiconductor laser chip and a spatial light modulator SLM which is optically connected to the semiconductor laser chip. The semiconductor laser chip LDC includes an active layer 4, a pair of cladding layers 2 and 7 sandwiching the active layer 4, and a diffraction grating layer 6 which is optically connected to the active layer 4. The spatial light modulator SLM includes a common electrode 25, a plurality of pixel electrodes 21, and a liquid crystal layer LC arranged between the common electrode 25 and the pixel electrodes 21. A laser beam output in a thickness direction of the diffraction grating layer 6 is modulated and reflected by the spatial light modulator SLM and is output to the outside.