Laser Wavelength Sweep Continuity via Feedback Control
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Solution Overview
Problem
Swept-wavelength lasers experience discontinuities and non-linearity due to mode hops, which affect the accuracy and quality of applications like optical coherence tomography and telecommunications, and existing solutions are either temporary or require expensive equipment for calibration.
Innovation Solution
A laser system with a processor-controlled wavelength tuning mechanism that uses post-sweep feedback from monitoring devices to adjust control currents and reduce or eliminate mode hops, maintaining a continuous and monotonic wavelength sweep by analyzing multivariate optical amplitude feedback data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mode hops are prevented through accurate, tightly-toleranced components and precision alignment, then wavelength continuity is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent employs feedback control by monitoring the laser wavelength during sweeping and dynamically adjusting control parameters to prevent mode hops. The system detects wavelength discontinuities and applies corrective adjustments in real-time, eliminating the need for extremely tight component tolerances and precision alignment while maintaining wavelength continuity.
Solution Approach 2:
The patent changes control parameters (such as current injection levels, temperature, or cavity length) dynamically during the laser sweeping process to maintain continuous wavelength operation. By adjusting these parameters in response to detected mode hop conditions, the system prevents discontinuities without requiring fixed, tightly-toleranced components.
2Reliability
If real-time elements such as piezoelectric transducers are used to adjust cavity length, then wavelength continuity is improved, but device complexity and cost increase
Solution Approach 1:
The system uses feedback control to monitor wavelength during sweeping and adjusts control parameters accordingly. This software-based feedback mechanism replaces the need for complex real-time hardware adjustment elements like piezoelectric transducers, achieving wavelength continuity through intelligent control rather than mechanical intervention.
Solution Approach 2:
The patent replaces mechanical real-time adjustment mechanisms (such as piezoelectric transducers that physically change cavity length) with electronic/software-based control of laser parameters. This substitution eliminates complex mechanical components while achieving the same goal of preventing mode hops through dynamic parameter adjustment.
3Reliability
If the laser is carefully aligned and components are tightly toleranced, then mode hops are prevented at a point in time, but additional discontinuities occur over time due to temperature and vibration changes
Solution Approach 1:
The patent implements continuous feedback monitoring of the laser wavelength during operation. By detecting mode hops and wavelength deviations in real-time and applying corrective adjustments to control parameters, the system maintains wavelength continuity over extended periods despite temperature changes, vibrations, and component aging that would otherwise cause drift and additional discontinuities.
Data Source
AI summary
A system (10, 20) and method including a wavelength tuning mechanism and a laser path length tuning mechanism for reducing discontinuities in a sweep range. A processor (14) is coupled to a wavelength monitoring device (18) and the tuning mechanisms. The processor analyzes data from the wavelength monitor to adjust the wavelength tuning and cavity length tuning at discontinuities in the wavelength sweep to reduce the discontinuities.