Photonic Crystal Optical Scanning Element for Fast Angle Control
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Solution Overview
Problem
Existing optical scanning elements have limitations such as insufficient scan angles, requiring multiple light sources with different wavelengths and slow response times due to wavelength-dependent deflection or temperature-dependent refractive index changes.
Innovation Solution
An optical scanning element utilizing a photonic crystal layer with periodically formed holes and a diffraction grating, combined with electrodes, allows for rapid angle changes through voltage application, enabling large scan angles and downsizing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a light deflector with wavelength-dependent deflection angle is used, then the deflection angle can be adjusted for different wavelengths, but multiple light sources with different wavelengths are required which increases device complexity
Solution Approach 1:
The patent changes the refractive index parameter of the electro-optical crystal substrate by applying voltage to electrodes. This voltage-induced refractive index change modifies the emission angle of light from the photonic crystal waveguide, enabling deflection angle adjustment without changing wavelength or requiring multiple light sources
Solution Approach 2:
The patent replaces the mechanical/thermal approach (heating the element to change refractive index) with an electrical approach (applying voltage to electrodes to change refractive index via electro-optical effect). This substitution achieves faster response and eliminates the need for multiple light sources
2Adaptability or versatility
If the light deflector is heated to change the deflection angle, then the emission angle can be adjusted, but the response time becomes slow
Solution Approach 1:
The patent substitutes thermal heating with electrical voltage application. The electro-optical effect responds almost instantaneously to voltage changes, replacing the slow thermal diffusion process of heating and achieving fast response time while maintaining emission angle adjustability
Solution Approach 2:
The patent changes the refractive index parameter through electrical voltage rather than thermal heating. This parameter change method provides rapid response because electrical fields establish almost instantly compared to thermal fields, enabling fast emission angle adjustment
3Device complexity
If a conventional light deflector is used, then the structure is relatively simple, but the scan angle is insufficient
Solution Approach 1:
The patent uses a composite structure combining photonic crystal waveguide (periodic hole pattern in electro-optical crystal) with diffraction grating and electrode system. This composite design achieves large scan angle by leveraging the synergistic effects of photonic bandgap, diffraction, and electro-optical modulation while maintaining reasonable structural complexity
Solution Approach 2:
The patent introduces a new dimension of control by applying voltage in the electrical domain to modulate the optical properties of the photonic crystal. This additional control dimension enables large scan angle adjustment without significantly increasing structural complexity
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 achieves a scanning element with a wide scan angle, quick responsiveness, and reduced size, overcoming the limitations of existing technologies by using electro-optical crystals to control refractive index changes with voltage, thus reducing costs and complexity.
Implementation Method 1
utilizing a photonic crystal layer with periodically formed holes and a diffraction grating, combined with electrodes, allows for rapid angle changes through voltage application
Implementation Method 2
a diffraction grating arranged in at least one portion selected from an upper portion, a left side surface portion, and a right side surface portion of the optical waveguide
Implementation Method 3
using electro-optical crystals to control refractive index changes with voltage
Data Source
AI summary
Provided is an optical scanning element, which has a large scan angle, is quickly responsive, and can be downsized. The optical scanning element includes: a photonic crystal layer having holes periodically formed in an electro-optical crystal substrate; a line-defect optical waveguide formed in the photonic crystal layer; a diffraction grating arranged in at least one portion selected from an upper portion, a left side surface portion, and a right side surface portion of the optical waveguide; and electrodes arranged on a left side and a right side of the optical waveguide. The optical scanning element is configured so that an emission angle of light emitted from an upper surface of the optical waveguide is changed.