Semiconductor Laser Dual Ring Resonators Wavelength Tuning
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Solution Overview
Problem
Existing wavelength tunable semiconductor lasers face increased optical loss due to smaller bend radii in ring resonators, which affects the free spectral range and optical intensity of the laser output.
Innovation Solution
The semiconductor laser design includes two ring resonators with different free spectral ranges, connected in series through an optical waveguide, where the first ring resonator has a larger FSR than the second, allowing for sharper wavelength-transmittance characteristics and reduced bending loss by using smaller bend radii, while maintaining high optical intensity through specific optical coupler configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If one ring resonator has a larger FSR value to achieve wavelength tuning, then the optical path length of its waveguide is decreased, but the bend radius becomes small resulting in increased bending loss
Solution Approach 1:
The patent divides the single ring resonator into multiple ring resonators (first ring resonator with larger FSR and second ring resonator with smaller FSR). Each ring resonator has an optimized bend radius that minimizes bending loss, while their combined FSR characteristics provide the desired wavelength tuning capability without requiring any single resonator to have a excessively small bend radius
2Measurement precision
If multiple ring resonators with different FSRs are used to achieve wavelength tuning, then the wavelength-transmittance characteristics become sharper, but the device complexity increases
Solution Approach 1:
The patent combines multiple ring resonators with different FSR characteristics into a unified laser device where they share common components (gain region, DBR region, optical waveguide, end facet). This merging approach achieves sharp wavelength-transmittance characteristics while avoiding the complexity of completely separate resonator systems, as the resonators work together within a single integrated cavity
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 configuration enables sharper peak waveforms in wavelength-transmittance characteristics, resulting in a narrower emission wavelength width and higher optical output intensity, effectively addressing the issue of increased optical loss in ring resonators with smaller bend radii.
Implementation Method 1
a distributed Bragg reflector (DBR) region including a diffraction grating
Implementation Method 2
The first ring resonator is optically coupled to the optical waveguide through the first optical coupler
Data Source
AI summary
A semiconductor laser includes a gain region; a distributed Bragg reflector (DBR) region including a diffraction grating; an end facet facing the DBR region with the gain region arranged therebetween; a first ring resonator including a first ring-like waveguide and a first optical coupler; a second ring resonator including a second ring-like waveguide and a second optical coupler; and an optical waveguide that is optically coupled to the end facet and extending in a predetermined optical-axis direction. The first and second ring resonators are optically coupled to the optical waveguide through the first and second optical couplers, respectively. Also, the DBR region, the gain region, and the end facet constitute a laser cavity. Further, the first ring resonator has a free spectral range different from a free spectral range of the second ring resonator.