Optical Scanning Element Using Electro-Optic Waveguide
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Solution Overview
Problem
Existing optical scanning devices require movable parts or suffer from low signal/noise ratios due to the need for multiple light-receiving elements, and devices using electro-optic effects for wide-angle scanning are limited by small refractive index changes and high driving voltages.
Innovation Solution
An optical scanning device with a single crystal optical waveguide and periodic domain inversion parts, where electrodes apply voltage to generate diffraction gratings, allowing light to be emitted in different directions without a movable part, enabling wide-angle scanning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mechanical scanning system (polygon mirror or MEMS) is used, then wide-angle scanning capability is achieved, but the device requires movable parts which reduces reliability and increases complexity
Solution Approach 1:
The patent replaces the mechanical scanning system (polygon mirror or MEMS with movable parts) with an all-optical waveguide system using electro-optic effects. The light direction is controlled by electric fields applied to domain inversion parts in the waveguide, eliminating mechanical moving parts entirely while achieving wide-angle scanning capability.
Solution Approach 2:
The patent changes the refractive index of the waveguide material through electro-optic effects by applying electric fields to domain inversion parts. This parameter change (refractive index modulation) enables dynamic control of light propagation direction without mechanical movement, resolving the contradiction between scanning capability and mechanical complexity.
2Adaptability or versatility
If light-receiving elements are divided to increase detection coverage, then scanning capability is improved, but the signal/noise ratio deteriorates due to reduced light per element
Solution Approach 1:
The patent replaces the multi-element detection system with a single light-receiving element that detects light emitted from different spatial positions within the waveguide. The electro-optic modulation creates directionally controlled light emission, allowing one detector to capture signals from multiple directions, thereby maintaining detection coverage while improving signal strength and noise ratio.
Solution Approach 2:
The patent transitions from a planar array of multiple detection elements to a three-dimensional light emission scheme within the waveguide volume. Light is emitted from different positions and directions within the waveguide structure, allowing a single detector to receive signals from multiple spatial locations, effectively achieving multi-point detection without dividing the receiving element.
3Measurement precision
If the power of the light source is increased to compensate for low reflected light, then the signal/noise ratio is improved, but the cost increases and eye safety problems arise
Solution Approach 1:
The patent replaces the high-power light source approach with an efficient optical waveguide system that minimizes light loss. The waveguide structure confines and guides light with high efficiency, and the electro-optic modulation enables precise directional control, allowing effective operation at lower light source powers while maintaining signal quality and ensuring eye safety.
Solution Approach 2:
The optical waveguide system performs self-focusing and self-guiding of light, maintaining high light intensity throughout the propagation path without requiring external amplification. The electro-optic modulation efficiently controls light direction with minimal energy loss, allowing the system to operate effectively at low power levels while maintaining measurement precision.
4Device complexity
If electrodes are placed directly on the optical waveguide, then the device structure is simplified, but light emission efficiency is reduced due to electrode obstruction
Solution Approach 1:
The patent moves the electrodes from the top surface plane to the side surfaces of the waveguide, utilizing the vertical dimension. This side-face electrode configuration allows electric fields to be applied effectively for electro-optic modulation while leaving the top emission surface unobstructed, thereby maintaining both structural simplicity and high light emission efficiency.
Solution Approach 2:
The patent segments the electrode structure into multiple independent electrodes positioned on different side faces of the waveguide. This segmentation allows independent control of electric fields from different directions, enabling precise spatial modulation of light emission while maintaining open top surfaces for efficient light extraction.
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 device achieves wide-angle scanning without movable parts, improving signal/noise ratios and reducing the need for high-powered light sources, while maintaining efficient light emission and detection capabilities.
Implementation Method 1
an optical waveguide comprising a single crystal having electro-optic effect
Implementation Method 2
generate a diffraction grating in each of the periodic domain inversion parts... a propagation light is emitted to the outside of the optical scanning device as a diffracted light
Data Source
AI summary
An optical scanning device includes a supporting body 2; an optical waveguide composed of a single crystal having electro-optic effect and integrated with the supporting body directly or through a clad layer; a plurality of periodic domain inversion parts formed in the optical waveguide, the periodic domain inversion parts having periods different from each other; and a plurality of electrodes capable of applying voltages on the periodic domain inversion parts, respectively, to generate diffraction gratings in the periodic domain inversion parts, respectively. The clad layer is composed of a material having a refractive index lower than a refractive index of the single crystal forming the optical waveguide. Each of the periodic domain inversion parts on which the voltage is applied is selected to generate the diffraction grating in the selected periodic domain inversion part so that a propagation light propagated in the optical waveguide is emitted to the outside of the optical scanning device as a diffracted light.