Pseudo-Random Phased Array Eliminates Grating Lobes
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Solution Overview
Problem
Current two-dimensional optical phased arrays face limitations such as slow steering speed, temperature sensitivity, grating lobes, and limited field of regard due to the use of liquid crystal or optical waveguide technologies, which hinder their effectiveness in military and commercial applications.
Innovation Solution
A two-dimensional optical phased array constructed as a stacked assembly of multiple chips with optical waveguide structures, metal electrodes, and dielectric filling, featuring pseudo-random emitter spacing and microlenses to eliminate grating lobes and enhance steering speed, operating over a wide temperature range and multiple wavelength bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If liquid crystal based optical phased array is used, then power consumption is low, but steering speed is slow (10's of milliseconds)
Solution Approach 1:
The optical phased array is segmented into multiple independent emitter elements arranged in a two-dimensional array, where each element can be independently controlled by separate electrodes. This segmentation allows parallel control of multiple elements, enabling fast beam steering without the slow response time of liquid crystal-based systems.
Solution Approach 2:
The patent replaces liquid crystal-based phase modulation with a direct electro-optic modulation approach using transparent conducting oxide electrodes. This substitution eliminates the need for liquid crystal molecules to reorient, achieving sub-millisecond response times while maintaining low power consumption through capacitive charging of the electrode structures.
2Ease of manufacture
If regular spaced emitter array is used, then manufacturing is simple, but grating lobes are generated reducing beam quality
Solution Approach 1:
The patent employs a pseudo-random asymmetric spacing pattern for the emitter elements rather than a regular periodic arrangement. This asymmetric distribution eliminates grating lobes by preventing constructive interference at unwanted angles, while the pseudo-random nature allows for simplified fabrication processes compared to precisely engineered aperiodic structures.
Solution Approach 2:
The emitter spacing parameters are varied according to a pseudo-random sequence, changing the spatial distribution characteristics of the array. This parameter variation eliminates the periodicity that causes grating lobes, improving beam quality without requiring complex manufacturing precision.
3Device complexity
If fixed aperture phased array is used, then structure is simple, but field of regard is limited
Solution Approach 1:
The patent implements dynamic beam steering capability by independently controlling the phase and amplitude of each emitter element through electronic modulation. This dynamic control allows the beam to be steered across a wide field of regard (>120 degrees) without any mechanical movement, maintaining structural simplicity while achieving high adaptability.
Solution Approach 2:
The two-dimensional emitter array structure serves multiple functions: it provides wide field of regard coverage, enables fast beam steering, and maintains structural simplicity. The same array configuration supports operation across different wavelength bands, enhancing versatility without increasing device complexity.
4Device complexity
If single wavelength phased array is used, then design is simple, but multi-band operation capability is lost
Solution Approach 1:
The patent designs the emitter elements and interconnect structures to be wavelength-agile, allowing the same physical structure to operate across multiple wavelength bands (e.g., 1.55 μm, 10.6 μm). The transparent conducting oxide electrodes and waveguide structures are engineered to support broad spectral operation, providing multi-band capability without increasing design complexity.
Solution Approach 2:
The optical properties of the emitter elements are engineered to be可调 (tunable) across different wavelength ranges by modifying the refractive index and absorption characteristics of the materials. This allows the phased array to maintain its structural simplicity while adapting to different wavelength bands through material parameter optimization.
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 enables fast beam steering (less than 1 millisecond), large field of regard (>120°), and simultaneous multi-wavelength operation with negligible sidelobes, making it suitable for infrared countermeasures and compact laser radar systems while being robust to temperature and vibration.
Implementation Method 1
optical waveguide structures
Implementation Method 2
microlenses to eliminate grating lobes
Data Source
AI summary
A phased array that comprises a predetermined number of emitter/receiver elements; said emitter/receiver elements being arranged on a array formed of stacked rows, wherein the emitter/receiver elements in each row of the array are distributed according to a pseudo-random pattern; and the heights of the rows vary according to a pseudo-random pattern.