Integrated Optical Gyroscope with Spectral Vernier Readout
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Solution Overview
Problem
Existing optical gyroscopes are bulky, require complex calibration, and suffer from vibration and temperature issues, with limited miniaturization due to fiber bend radii and semiconductor ring laser non-linearities, necessitating the development of highly integrated, miniaturized, and cost-effective solutions for accurate angular velocity measurement.
Innovation Solution
The optical gyroscope incorporates a passive closed-path optical cavity with extraction means and a readout channel featuring an interferometric device, enabling spectral modification and detection of optical power levels, utilizing a planar lightwave circuit with integrated components like silicon-on-insulator or III-V materials to achieve compactness and robustness, and employs phase modulation to suppress backscattering noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If fiber-based gyroscopes are used, then measurement accuracy is maintained, but device size and complexity increase due to limited bend radii preventing further scaling
Solution Approach 1:
The patent replaces fiber-optic mechanical structures with integrated semiconductor ring laser structures fabricated using standard CMOS or similar semiconductor manufacturing processes. This substitution enables miniaturization while maintaining measurement functionality through on-chip optical waveguides that form the resonator cavity, eliminating the need for bulky fiber coils.
Solution Approach 2:
The patent integrates multiple functional components (optical waveguides, resonator cavity, readout optics, and detection elements) onto a single semiconductor chip. This merging of functions into a compact integrated structure achieves both size reduction and maintained measurement accuracy through precise on-chip optical path control.
2Volume of moving object
If semiconductor ring lasers are used for miniaturization, then device size is reduced, but measurement precision deteriorates due to non-linearities and intra-cavity backscattering
Solution Approach 1:
The patent converts the harmful effect of intra-cavity backscattering into a useful signal by implementing a readout scheme that detects backscattered light intensity variations. The backscattering that previously caused noise and measurement errors is now utilized as the measurement signal itself, enabling accurate angular velocity detection while maintaining compact semiconductor ring laser structure.
3Device complexity
If passive resonator cavities are integrated on chip, then device integration is improved, but external optical access and test equipment remain cumbersome
Solution Approach 1:
The patent combines the resonator cavity, readout optics, and detection elements into a single integrated on-chip structure. The readout optics are fabricated directly on the chip using standard semiconductor processing techniques, eliminating the need for external optical access and test equipment while maintaining full measurement functionality.
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 results in highly sensitive, compact, and cost-effective optical gyroscopes capable of accurate angular velocity measurements with reduced noise and external equipment requirements, suitable for industrial applications.
Implementation Method 1
They rely on the Sagnac effect, which describes the physical effect of a rotating frame on the optical phases of counter-propagating light beams.
Implementation Method 2
the at least one readout channel comprises an interferometric device, realizing the spectral modification of an extracted fraction of the received first optical signal
Data Source
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AI summary
An optical gyroscope (100, 200, 300, 400) and a method for measuring an angular velocity of rotation are described. A closed-path optical cavity (106) is configured for receiving at least a first optical signal circulating as at least one cavity mode of pre-determined orientation (CW, CCW) inside the optical cavity. Extraction means (112, 122), in optical communication with the optical cavity (106), are extracting a fraction of at least the circulating first optical signal from the optical cavity, wherein an amplitude of the extracted fraction is increasing when a resonance condition for the optical cavity in optical communication with the extraction means is approached. A readout channel included in the optical gyroscope is comprising an interferometric device (113, 123) adapted to spectrally modify the extracted fraction so as to produce a spectral Vernier effect. A difference between free spectral ranges of the interferometric device and the optical cavity (106) is larger than the associated spectral widths. Readout detectors (114, 124) are included in the readout channel for detecting optical power levels of the spectrally modified optical signal, based on which the angular velocity is determined.