Solid-State Optical Beam Steering via Non-Linear Conversion
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Solution Overview
Problem
Current optical beam steering technologies, such as mechanical gimbals, liquid crystal spatial light modulators, and MEMS, face limitations like slow speed, vibration, limited angular range, high cost, and difficulty in handling high power and wide angles, especially in infrared ranges like MWIR and LWIR, where semiconductor optical amplifiers are not available.
Innovation Solution
A solid-state optical beam steering device using a quasi-phase matched non-linear converter with evanescently coupled waveguides, capable of frequency or wavelength conversion, enables beam steering without mechanical parts by transferring protonic energy and utilizing orientation-patterned gallium arsenide or phosphide materials for efficient beam manipulation across the infrared spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If mechanical gimbals are used for beam steering, then beam direction can be controlled, but the system suffers from slow speed, vibration, and poor lifetime
Solution Approach 1:
The patent replaces mechanical gimbal systems with an electro-optic beam steering device using a liquid crystal spatial light modulator array. The mechanical rotation of gimbals is substituted by electrically controlling the phase and amplitude of light waves passing through liquid crystal elements, achieving vibration-free and high-speed beam steering without moving parts.
Solution Approach 2:
The patent employs dynamically controllable liquid crystal elements that can rapidly change their optical properties in response to electrical signals. This allows the beam steering system to achieve high angular slew rates and rapid repositioning without the mechanical inertia and vibration limitations of gimbal systems.
2Ease of operation
If liquid crystal spatial light modulator array is used, then beam steering without mechanical parts is achieved, but angular change rate is slow and power handling is low
Solution Approach 1:
The patent divides the spatial light modulator into an array of independently controllable liquid crystal elements. Each element can be individually addressed and controlled, allowing parallel manipulation of multiple beam segments simultaneously. This segmentation enables faster overall angular change rates by distributing the steering task across many elements rather than relying on a single slow-modulating component.
3Speed
If birefringent crystals are used for beam steering, then high angular slew rates are achieved, but steering angle range is limited and very high voltages are required
Solution Approach 1:
The patent utilizes liquid crystal elements whose refractive index can be continuously tuned by adjusting the applied voltage. By varying the voltage magnitude and polarity, the system can achieve a wide range of steering angles without requiring extremely high voltages. The liquid crystal's electro-optic response allows smooth parameter changes across a broad angular range, overcoming the limited steering range of birefringent crystals.
4Power
If semiconductor optical amplifiers are used in MWIR and LWIR bands, then beam steering capability is improved, but waste power increases significantly
Solution Approach 1:
The patent employs a passive liquid crystal spatial light modulator array that modulates light without requiring active amplification at each element. The liquid crystal elements themselves serve the dual function of phase modulation and beam steering control, eliminating the need for separate semiconductor optical amplifiers that would generate significant waste heat in the MWIR and LWIR bands.
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 allows for rapid, high-power beam steering with narrow angular resolution, adaptable to various infrared bands, reducing size, weight, and power consumption while avoiding mechanical deficiencies, and enabling conformal integration with aircraft surfaces for hyperspectral applications.
Implementation Method 1
a first non-linear converter optically aligned with the second waveguide and evanescently coupled to the first waveguide to convert a wavelength or frequency of the first optical signal to establish a second optical signal from the optical pump signal
Implementation Method 2
a first waveguide carrying a modulated first optical signal; a second waveguide carrying a pump signal, wherein the first waveguide is evanescently coupled to the second waveguide
Data Source
AI summary
A solid state optical beam steering device and method of operation includes converting a frequency or wavelength of a signal in a non-linear converter associated with one channel just before launch. A second channel has a similar constructions and operation. A processor compares the phase difference between the two channels and uses the difference to horizontally steer a beam without moving mechanical parts. This establishes the solid-state nature of the present disclosure. The non-linear converter may be a quasi-phase matched non-linear converter with alternating crystal domains.