PIC Optical Transmitter With Beam Steering for Speckle Reduction
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Solution Overview
Problem
Existing spectrophotometric systems face challenges in accurately measuring chemical compositions of tissues due to sparse wavelength sampling and laser speckle noise, which degrades signal-to-noise ratio and requires frequent calibration.
Innovation Solution
A photonic integrated circuit (PIC) with an array of lasers, wavelength multiplexers, couplers, and wavelength meters is designed to deliver high optical power efficiently while mitigating speckle noise through beam steering and wavelength measurement, using passive and active optical phased arrays and temperature sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single laser is used for spectroscopic sensing, then the device complexity is low, but the wavelength sampling is sparse and speckle noise is high
Solution Approach 1:
The system segments the light source into multiple lasers, each operating at a distinct wavelength. This segmentation enables dense wavelength sampling across the spectral range, transforming a single-laser sparse sampling system into a multi-laser high-resolution system without requiring a single complex tunable laser
2Measurement precision
If multiple lasers are used to increase wavelength sampling density, then the measurement precision improves, but laser speckle noise increases
Solution Approach 1:
The patent introduces spatial diversity by steering multiple laser beams through different angles onto the tissue sample. This adds a spatial dimension to the measurement, where beams from different angles produce different speckle patterns that can be averaged or processed to reduce overall speckle noise while maintaining dense wavelength sampling
3Power
If optical power is delivered efficiently to the sample, then the signal-to-noise ratio improves, but calibration requirements increase
Solution Approach 1:
The system incorporates wavelength meters that provide real-time feedback on the actual wavelengths emitted by each laser. This feedback enables dynamic calibration and compensation for wavelength drift, allowing the system to maintain accurate spectroscopic measurements without requiring frequent manual recalibration, thus reducing the burden of calibration while preserving high optical power delivery efficiency
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 achieves precise wavelength measurement and reduced speckle noise, enabling accurate spectroscopic sensing of tissue chemical compositions with improved signal quality and reduced calibration needs.
Implementation Method 1
a passive optical phased array configured to steer an output beam through an angle corresponding to a wavelength change
Implementation Method 2
a first wavelength multiplexer, connected to the first array of lasers
Implementation Method 3
a first coupler, connected to the wavelength multiplexer; and a first wavelength meter, connected to a first output of the first coupler
Data Source
AI summary
A system including an optical transmitter. In some embodiments, the system includes: a first array of lasers; a first wavelength multiplexer, connected to the first array of lasers; a first coupler, connected to the wavelength multiplexer; and a first wavelength meter, connected to a first output of the first coupler.