Tunable Laser Thermal Phase Retarder Alignment
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Solution Overview
Problem
Existing tunable lasers face challenges with alignment and control due to bulky components and low optical powers, limiting their widespread use in optical telecommunication systems, particularly in achieving wavelength agility and high optical powers.
Innovation Solution
A tunable laser design incorporating a semiconductor gain medium, a thermally tunable frequency selector, and a thermally tunable phase retarder in an external cavity configuration, with integrated resistive heaters, allowing for easy alignment and high optical power generation across the C- or L-bands.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If bulky free-space optical components are used in tunable lasers, then wavelength tunability is achieved, but device size and alignment difficulty increase
Solution Approach 1:
The patent integrates the frequency selector and phase retarder into a single unified component structure, where the phase retarder is positioned within the optical cavity formed by the frequency selector's mirrors. This merging eliminates the need for separate alignment of multiple discrete components, thereby reducing alignment difficulty while maintaining full wavelength tunability across C- and L-bands.
2Volume of moving object
If integrated tunable lasers are fabricated, then device size is reduced, but manufacturing complexity and alignment challenges increase
Solution Approach 1:
The integrated device is segmented into functionally distinct regions: a frequency selector section with tunable mirrors and an optical gain medium section with the phase retarder embedded in the cavity. This segmentation allows each section to be optimized independently for its specific function while being fabricated as an integrated unit, reducing overall manufacturing complexity despite the compact size.
3Adaptability or versatility
If discrete filters are cascaded to achieve wide wavelength tuning, then wavelength range is extended, but alignment and control challenges increase
Solution Approach 1:
The frequency selector is designed as a universal component that can tune across both C-band and L-band wavelengths using a single device structure. The phase retarder within the optical cavity provides unified control for both frequency selection and mode stabilization, eliminating the need for multiple discrete filters and simplifying the control mechanism while achieving extended wavelength range.
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 solution enables compact, high-yield manufacturing of tunable lasers with improved alignment and control, enhancing wavelength tunability and optical power output, thus addressing the limitations of previous designs.
Implementation Method 1
a thermally tunable frequency selector
Implementation Method 2
a thermally tunable phase retarder
Implementation Method 3
integrated resistive heaters
Implementation Method 4
a semiconductor gain medium
Data Source
AI summary
A tunable laser includes an optical cavity comprising a first and second mirror. A gain medium is positioned in the optical cavity that generates stimulated emission in the optical cavity when biased. A thermally tunable optical filter is positioned in the optical cavity that is heated to a temperature that selects a desired optical mode of the optical cavity. A thermally tunable optical phase retarder is positioned in the optical cavity that is heated to a temperature which changes an optical path length in the optical cavity by an amount corresponding to a resonant frequency of the tunable optical filter so that a phase-matching condition of the optical cavity is shifted to the desired optical mode of the optical cavity selected by the thermally tunable optical filter.