Ring Resonator Reflection Filter for Stable Single-Mode Tunable Lasers
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Solution Overview
Problem
Existing wavelength-tunable laser devices face challenges in achieving fine adjustment of phase to reduce laser linewidth and select resonator modes effectively, especially when the spacing between resonator modes is narrow, making it difficult to achieve stable single mode oscillation.
Innovation Solution
A reflection filter device with a ring resonator and dual-branch portion, including a phase adjuster and refractive index changing units, is integrated into the laser resonator, generating comb-shaped reflection spectra with overlapping peaks to facilitate precise wavelength tuning and phase adjustment, allowing for finer control of resonator modes and laser emission wavelength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resonator length is increased to reduce laser linewidth, then the longitudinal mode spacing is reduced, but it becomes difficult to achieve stable single mode oscillation
Solution Approach 1:
The reflection filter is segmented into multiple functional components: a ring resonator for wavelength selection, dual-branch portions for signal splitting and combining, and phase adjusters for fine-tuning. This segmentation allows independent optimization of each component to achieve both narrow linewidth and stable single mode oscillation.
Solution Approach 2:
The patent introduces dynamically adjustable phase shifters in the dual-branch portions that allow real-time control of the optical path difference between branches. This dynamic adjustment capability enables the system to maintain stable single mode oscillation while achieving narrow linewidth by adaptively tuning the interference conditions.
2Measurement precision
If the resonator length is increased to reduce laser linewidth, then the device complexity increases, but fine adjustment of phase becomes difficult
Solution Approach 1:
The patent introduces phase adjusters as intermediary elements between the fixed resonator structure and the output. These phase adjusters serve as mediators that simplify the control interface by providing direct electrical control over optical phase, eliminating the need for complex mechanical adjustments even in long resonators.
Solution Approach 2:
The patent replaces mechanical phase adjustment mechanisms with electrically controlled phase shifters. This substitution eliminates complex mechanical structures while enabling precise phase control for linewidth reduction, thereby reducing device complexity despite increased resonator length.
3Measurement precision
If the resonator length is increased to reduce laser linewidth, then the manufacturing precision requirements increase, but fine adjustment of phase is needed
Solution Approach 1:
The patent uses programmatically controllable phase shifters that allow post-fabrication tuning of phase parameters. This capability compensates for manufacturing variations in long resonators by enabling electronic adjustment of the optical path difference, thereby achieving narrow linewidth without requiring extremely precise fabrication tolerances.
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 easier selection of resonator modes and stable single mode oscillation by allowing for precise adjustment of the laser emission wavelength, even when resonator modes are closely spaced, thereby reducing laser linewidth and improving side mode suppression ratio.
Implementation Method 1
a ring resonator filter including a ring-shaped waveguide and two straight waveguides, each of the two straight waveguides being optically coupled to the ring-shaped waveguide
Implementation Method 2
at least one of the two arms is equipped with a phase adjuster
Implementation Method 3
a refractive index changing unit arranged along the phase adjuster
Implementation Method 4
a laser resonator including a diffraction grating
Data Source
AI summary
A reflection filter device includes: a ring resonator filter including a ring-shaped waveguide and two arms, each of the two arms being optically coupled to the ring-shaped waveguide; and a dual-branch portion including a light input/output port and two branch ports, the light input/output port being configured to allow input and output of light, the two branch ports being configured to allow output of the light input from the light input/output port, the light being split into two, the two arms being connected to the two branch ports, respectively, at least one of the two arms being equipped with a phase adjuster.