PIC Spectrometer Ring Resonator Array Calibration
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Solution Overview
Problem
Current optical spectrometers for space-flight applications are bulky and heavy, limiting their size, weight, and power efficiency, and they require precise fabrication of ring resonators for high accuracy.
Innovation Solution
A photonic integrated circuit (PIC) spectrometer with an array of integrated ring resonators and detectors, utilizing a matrix multiplication process to determine the spectral content of light, and featuring a CMOS-compatible photonic platform for reduced size and weight.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional optical spectrometers are used for space-flight applications, then spectral measurement capability is achieved, but size and weight become bulky and heavy
Solution Approach 1:
The patent replaces traditional mechanical optical components (gratings, prisms, moving parts) with a photonic integrated circuit that uses waveguide-based ring resonators to achieve spectral measurement. This substitution of mechanical systems with integrated photonic structures dramatically reduces size and weight while maintaining spectral measurement capability, making it suitable for space-flight applications.
Solution Approach 2:
The patent implements multiple ring resonators with different radii nested within a single integrated photonic chip structure. Each ring resonator is coupled to the same waveguide bus, allowing multiple spectral channels to be measured simultaneously or sequentially without requiring separate physical instruments, thereby compacting the overall system size.
2Measurement precision
If precise fabrication of ring resonators is performed, then measurement accuracy is improved, but manufacturing complexity and difficulty increase
Solution Approach 1:
The patent performs preliminary calibration by measuring the actual resonance wavelengths of each ring resonator before final operation. A calibration matrix is constructed based on these measured wavelengths, which compensates for any fabrication variations. This preliminary characterization action allows the system to achieve high measurement accuracy despite variations in manufacturing precision.
Solution Approach 2:
The patent implements a feedback mechanism where the measured resonance wavelengths of the ring resonators are used to update the calibration matrix. This feedback loop allows the system to adapt to actual device characteristics and maintain high measurement accuracy. The calibration matrix is repeatedly updated based on measured data, compensating for fabrication tolerances.
3Volume of moving object
If multiple ring resonators are integrated on a single chip, then device compactness is improved, but fabrication tolerances and manufacturing challenges increase
Solution Approach 1:
The patent designs ring resonators with different radii (e.g., 50 µm, 75 µm, 100 µm) to achieve different free spectral ranges and spectral coverage. By varying the geometric parameters of the ring resonators, the system can cover a broad spectral range (400-4000 nm) while maintaining compact integration. The calibration process further compensates for parameter variations due to fabrication tolerances.
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 PIC spectrometer achieves a broad spectral range from 400 nm to 4000 nm with high resolution (resolving power of 10^5 to 10^6) in a compact form, reducing size and weight significantly compared to traditional spectrometers.
Implementation Method 1
Each ring resonator of an array of integrated ring resonators and detectors is optically coupled to the optical bus and to at least one detector
Implementation Method 2
In a zoom mode, a plurality of ring resonator resonances can be tuned by the micro heaters to sample a spectrum across a resonator spectral range at high resolution
Implementation Method 3
The integrated optical spectrometer can include integrated silicon photodetectors responsive to a visible range from about 400 nm to 1000 nm
Data Source
AI summary
An integrated optical spectrometer includes an optical bus configured to accept a light to be measured. Each ring resonator of an array of integrated ring resonators and detectors is optically coupled to the optical bus and to at least one detector. A matrix multiplication process is operatively coupled to each detector. The matrix multiplication process determines based on data from the array of integrated ring resonators and detectors and a calibration matrix of the array of integrated ring resonators and detectors, a spectral content of the light to be measured. A method of calibrating and operating an integrated optical spectrometer, a method to generate a calibration matrix for a ring array of a photonic integrated circuit (PIC) spectrometer, and a method for spectrum reconstruction for a photonic integrated circuit (PIC) spectrometer are also described.