Subwavelength NLC Beam Steering via Vertical Electrodes
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current beam-steering devices for LiDAR applications face limitations such as slow scanning frequencies, limited field-of-view, and low optical efficiency due to mechanical complexities, insertion loss, and high-order diffraction effects, particularly in transmission mode operations.
Innovation Solution
The use of subwavelength gaps infiltrated with nematic liquid crystals (NLC) between vertically positioned transparent electrodes, allowing for individual actuation and rapid reorientation of NLC molecules to achieve high deflection efficiencies and wide field-of-view, while suppressing higher diffracted orders and reducing response time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional LC modulators are used for beam steering in transmission mode, then device integration and lightweight operation are improved, but scanning frequency remains limited to kHz regime
Solution Approach 1:
The device divides the LC layer into multiple independently controllable pixel regions, each with its own electrode. This segmentation allows parallel control of multiple beam directions simultaneously, enabling faster scanning frequencies while maintaining easy on-chip integration of individual pixel control.
2Adaptability or versatility
If conventional LC modulators operate at large deflection angles, then beam steering capability is improved, but optical efficiency decreases due to high-order diffraction effects
Solution Approach 1:
Each pixel region is designed with locally optimized electrode geometries and LC cell thicknesses tailored to achieve specific deflection angles. This local quality optimization allows large deflection angles to be achieved with minimal high-order diffraction effects, maintaining high optical efficiency across the entire steering range.
3Adaptability or versatility
If conventional beam steering devices are used, then field-of-view is limited, but device complexity and mechanical requirements increase
Solution Approach 1:
The invention replaces mechanical scanning systems with an all-optical transmission-mode LC modulator system. By using voltage-controlled LC reorientation rather than mechanical movement, the device achieves wide field-of-view capabilities without the mechanical complexity, bulkiness, and failure vulnerabilities of mechanical scanners.
4Speed
If integrated OPAs are used for high scanning frequencies, then scanning speed is improved, but output optical power is limited due to insertion loss
Solution Approach 1:
The invention introduces vertically positioned transparent electrodes as intermediaries between the LC layer and the incident light. These electrodes enable voltage-controlled LC reorientation in transmission mode with minimal insertion loss, allowing high scanning frequencies to be achieved while maintaining high output optical power levels.
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 approach enables high-speed, high-efficiency beam steering with wide field-of-view capabilities, achieving deflection angles of up to ±25° and optical efficiencies of 85%, significantly surpassing previous technologies in both speed and performance.
Implementation Method 1
the application of an electrical voltage can induce a controllable phase retardation to the transmitted beam, required to deflect the light from its initial direction
Implementation Method 2
LC molecules exhibit uniaxial birefringence in the range 0.05-0.45, with an optical axis aligned with the longitudinal axis of the molecules
Implementation Method 3
a voltage application causes bulk elastic deformations leading to collective rotations of the LC molecules along (perpendicularly) to the electric field direction
Implementation Method 4
the application of an electrical voltage can induce a controllable phase retardation to the transmitted beam, required to deflect the light from its initial direction
Implementation Method 5
The LC reorientation occurs to minimize the LC free energy resulting from the competition between the electrical and the anchoring forces
Data Source
AI summary
A beam-steering device (BSD) including a dielectric substrate (DS) and a cover window (DCW), both transparent; a plurality of transparent conducting rails (VEL), extending parallel to each other between the dielectric surfaces, dividing a space between the substrates into a plurality of elongated cells (LC0-LC3); a nematic liquid crystal (LC) filling the elongated cells; and a plurality of electrical interconnections (ELI) suitable to apply an electric potential (V0-VN) to each one of the conducting rails. The pitch P of the conducting rails is smaller than an optical wavelength λ; and the height H of the conducting rails is at least equal to λ/Δn, Δn being the birefringence of the liquid crystal at the optical wavelength.