Optical Phased Array Chip Calibration via Reversed Laser Injection
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Solution Overview
Problem
Existing calibration systems for optical phased array (OPA) chips suffer from low standardization and automation, leading to inefficient and non-universal testing methods that are limited by the tradeoff between refresh rate, field of view, and angular resolution, especially when evaluating high-channel count OPAs.
Innovation Solution
A calibration system utilizing reversed injection of collimated laser for OPA chips, combined with phase-shift adjustments and automated modules for precise alignment and power measurement, enabling high-throughput wafer-level and batch calibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If free space beam quality evaluation is used with SWIR camera, then beam quality can be evaluated, but refresh rate is limited and throughput is low
Solution Approach 1:
The patent replaces the mechanical/imaging-based SWIR camera system with an electrical measurement system. Instead of using optical imaging to evaluate beam quality, the invention uses electrical signals to directly measure and characterize the optical field, enabling much faster measurement speeds that are not limited by camera refresh rates.
Solution Approach 2:
The patent introduces an intermediary measurement approach that uses electrical signals as a mediator between the optical field and the measurement system. By converting optical field characteristics into electrical measurements, the system achieves high-speed characterization without the bottlenecks of direct optical imaging.
2Measurement precision
If Fourier optical imaging system is used, then far field pattern can be mapped, but field of view and angular resolution have tradeoff limitations
Solution Approach 1:
The patent moves the measurement from the spatial domain (optical imaging) to the electrical signal domain. By measuring optical field characteristics through electrical means rather than optical imaging, the system avoids the inherent tradeoffs between field of view and angular resolution that constrain Fourier optical imaging systems.
3Reliability
If customized test configurations are used for verification, then individual claims can be validated, but standardization and automation are low
Solution Approach 1:
The patent creates a universal electrical measurement system that can validate multiple individual claims and test configurations through a single standardized interface. The electrical measurement approach provides a multi-functional platform that maintains verification accuracy while enabling automated testing across different OPA chip designs and configurations.
4Ease of operation
If on-chip optical field control and free space beam quality evaluation are combined, then calibration can be performed, but system complexity increases
Solution Approach 1:
The patent extracts the beam quality evaluation function from the physical optical path and relocates it to an electrical measurement domain. By separating the measurement function from the optical propagation path, the system reduces complexity while maintaining calibration capability.
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 system achieves efficient, automated, and flexible calibration of OPA chips, maximizing throughput and minimizing distortion, suitable for various aperture sizes and scales, with reduced reliance on high-performance SWIR cameras.
Implementation Method 1
The calibration methods for OPA chips comprises the steps of: reversely injecting collimated laser to an OPA chip under calibration to perform coherent beam combination on the collimated laser within the OPA chip
Implementation Method 2
reversely injecting collimated laser to an OPA chip under calibration to perform coherent beam combination on the collimated laser within the OPA chip
Implementation Method 3
each of the phase shifters comprises a tunable waveguide section with electric connections and an optical field control mechanism
Implementation Method 4
an optical field control mechanism including but not limited to the thermo-optical effect, the free carrier plasma dispersion effect, the piezoelectric effect, and the electro-optic effect
Data Source
AI summary
A calibration system and related methods for optical phased array chips. The calibration system includes an adjustable mount module, an infrared microscopic observation module, an arrayed driver module, a two-dimensional laser beam scanning module, a photoelectric conversion module and an upper computer, and utilizes computer-vision-enabled positioning and phase error compensation algorithms as software components. Collimated laser is emitted from the target beamforming angle and aimed at the emission aperture of the chip, and is subsequently sampled by the array elements in a reversed injection manner. Based on the reciprocity of light propagation, by maximizing the power reversely output from the bus waveguide of the optical phased array chip, beamforming at the target angle is achieved supported by software implementations of optimization algorithms. The system and related methods are readily achievable, highly automated, and offers fast and batch calibration with relatively low expenses, good flexibility and long-term compatibility.