Single-chip OCT With Digitally Variable Reference Arm
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Solution Overview
Problem
Current OCT systems are bulky, complex, and sensitive to alignment issues due to numerous fiber and free-space optical components, and they require sample scanning to obtain cross-sectional images, which complicates dispersion compensation and reduces signal-to-noise ratio (SNR).
Innovation Solution
An integrated-optics-based OCT system with a digitally variable reference arm and a delay controller that allows for digital control of the reference arm length and optical power, enabling simpler dispersion compensation and improved SNR, featuring a planar-lightwave circuit (PLC) with a 3-dB coupler, surface waveguides, and a beam combiner, along with photodetectors and a processor for processing interference signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If integrated-optics-based OCT system with digitally variable reference arm is used, then device complexity is reduced and SNR is improved, but manufacturing precision requirements increase due to monolithic integration on substrate
Solution Approach 1:
The patent merges multiple optical components (coupler, reference arm, sample arm, beam combiner, delay controller) into a single monolithic planar-lightwave circuit integrated on one substrate. This integration eliminates the need for separate fiber and free-space optical components, reducing overall system complexity while requiring precise monolithic fabrication techniques to maintain optical performance.
2Ease of operation
If digitally controlled delay controller is implemented, then dispersion compensation is simplified, but device complexity increases due to additional control mechanisms
Solution Approach 1:
The patent replaces traditional mechanical dispersion compensation methods (such as movable mirrors or manual adjustment mechanisms) with a digitally controlled delay controller implemented as an integrated optical circuit. The delay controller uses electronic digital signals to adjust optical path length, eliminating complex mechanical components while simplifying dispersion compensation operation through software control.
3Adaptability or versatility
If reference arm length is made variable through delay controller, then imaging flexibility is improved, but loss of energy increases due to additional optical path variations
Solution Approach 1:
The patent implements a dynamically adjustable reference arm length through the delay controller, which can vary the optical path length in real-time based on imaging requirements. This dynamic adjustment allows the system to adapt to different imaging depths and resolutions while minimizing optical power loss through efficient waveguide coupling and low-loss material design in the integrated circuit.
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 high-resolution imaging with reduced complexity in dispersion compensation and improved signal-to-noise ratio, overcoming the limitations of prior art by allowing digital adjustment of the reference arm length and optical power, thus enhancing imaging capabilities without the need for sample scanning.
Implementation Method 1
A 3-dB coupler distributes the input light signal into a sample signal and a reference signal
Implementation Method 2
A beam combiner combines the reference signal and the reflected signal to generate an interferometric signal
Implementation Method 3
A first photodetector provides an output signal based on the interferometric signal
Data Source
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AI summary
A high-performance single-chip, integrated-optics-based OCT system is disclosed, where the length of the reference arm is digitally variable. The reference arm includes a plurality of switch stages comprising a 2x2 tunable wavelength-independent waveguide switch that can direct an input light signal onto either of two different-length output waveguides. In some embodiments, the directional couplers are thermo-optic based. Some embodiments include a solid-state scanning system for scanning a sample signal along a line of object points on the sample under test.