Voltage-Controlled LC Wedge for Tunable Beam Steering
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Solution Overview
Problem
Existing optical beam steering technologies, such as glass wedges and liquid crystal (LC) arrays, face limitations in tunable range and suffer from diffraction scattering due to their segmented nature, which is problematic for applications like LIDAR and optical communication systems.
Innovation Solution
A single, large-sized voltage-controlled LC-based optical wedge is used to create a continuous, linear phase variation along its length, allowing for adjustable beam steering by varying the applied bias voltages, thereby overcoming the limitations of traditional methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an array of liquid crystal cells is used to provide beam steering, then the beam steering angle can be changed, but the segmented nature of multiple cells creates diffraction scattering of the propagating beam
Solution Approach 1:
The patent merges multiple separate LC cells into a single unitary LC cell structure. This single cell has continuous liquid crystal material without segmentation, eliminating the stepped phase profile that causes diffraction scattering. The continuous structure maintains beam steering capability while removing the harmful scattering effect caused by cell boundaries.
Solution Approach 2:
The patent applies segmentation in reverse by removing the segmentation that exists in conventional LC arrays. Instead of dividing the optical path into multiple discrete cells, the invention uses a single continuous LC cell where the liquid crystal material extends uniformly across the entire aperture, eliminating the interfaces between segments that cause diffraction.
2Device complexity
If a glass wedge device is used for beam steering, then the steering mechanism is simple, but the physical dimensions of the wedge are fixed and the available range of beam steering is not tunable over time
Solution Approach 1:
The patent transforms the static, fixed steering angle of a glass wedge into a dynamic, tunable steering angle by using voltage-controlled liquid crystal material. The refractive index of the LC material can be changed by applying different voltages, allowing the beam steering angle to be adjusted dynamically without changing the physical dimensions of the device structure.
Solution Approach 2:
The patent changes the refractive index parameter of the optical medium by applying different voltages to the liquid crystal material. This parameter change allows the beam steering angle to be tuned over a range of values while maintaining the same physical device structure, combining the simplicity of a fixed wedge with the tunability of variable optics.
3Adaptability or versatility
If a large number of separate LC cells are used to overcome the physical limitations of the glass wedge, then beam steering angle can be adjusted, but the need to individually control each cell increases device complexity
Solution Approach 1:
The patent combines multiple separate LC cells and their individual electrode structures into a single unitary LC cell with a unified electrode system. This merging reduces the total number of components, eliminates the need for individual cell control, and simplifies the overall device architecture while maintaining the ability to adjust beam steering angle through voltage 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
This solution enables active, controllable beam steering over a wide range, minimizing insertion loss, crosstalk, and polarization-dependent loss, while allowing for precise alignment and extended beam steering capabilities.
Implementation Method 1
a voltage-controlled optical wedge is formed by creating an adjustable voltage gradient along the length of a relatively large-sized unitary LC cell
Implementation Method 2
a glass wedge device that provides steering by mechanically rotating the wedge to change its angle of refraction
Data Source
AI summary
A voltage-controlled optical wedge is formed by creating an adjustable voltage gradient along the length of a relatively large-sized LC cell. A pair of bias voltages (AC voltages) are applied at the opposing side terminations of the LC cell, their RMS values selected to create a continuous phase variation along the length of the cell, where a defined phase variation is associated with a specific beam steering angle. Adjustments in the applied bias voltages (specifically, changes in the RMS values of the bias voltages) result in changing the beam steering angle, providing for active, controllable beam steering as a function of time. The LC cell may be configured to provide either a linear or nonlinear continuous phase variation, as preferred for different beam steering applications.