Self-Injection Locking Laser Tuning for Fast Low-Noise Modulation
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Solution Overview
Problem
Current self-injection locking laser systems have limited frequency agility due to slow tunability, which restricts their ability to achieve rapid frequency tuning while maintaining low phase noise and high spectral efficiency in applications like distributed fiber sensing and coherent LiDAR.
Innovation Solution
A method for operating a frequency agile tunable self-injection locking laser system by controlling the diode current and actuation voltage to optimize the refractive index of the optical resonator, allowing for a broad tuning range and maintaining self-injection locking, using piezo or electro-optical actuators to induce mechanical stress or electric displacement fields, thereby changing the effective optical path length.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If thermal tuning is used in integrated photonic devices, then frequency tuning capability is achieved, but tuning speed becomes slow due to thermal response time
Solution Approach 1:
The patent replaces the thermal (heat-based) tuning mechanism with a piezoelectric actuator that uses mechanical stress to tune the resonator frequency. This substitution eliminates the slow thermal response time while maintaining frequency tuning capability, directly resolving the contradiction between achieving frequency tuning and maintaining fast response speed.
2Speed
If rapid frequency tuning of the resonator is performed, then frequency agility is improved, but phase noise increases due to reduced photon lifetime
Solution Approach 1:
The patent changes the tuning parameter from thermal (affecting photon lifetime) to piezoelectric stress (affecting refractive index and physical dimensions). This parameter change allows rapid frequency tuning while maintaining the photon lifetime in the resonator, thereby resolving the contradiction between frequency agility and phase noise performance.
3Reliability
If discrete crystalline resonators are used for self-injection locking, then phase noise is reduced, but frequency agility becomes limited
Solution Approach 1:
The patent introduces a piezoelectric actuator that enables dynamic tuning of the resonator frequency while maintaining the self-injection locking condition. This dynamic capability transforms the previously static discrete crystalline resonator system into a frequency-agile system that can rapidly switch between frequencies while preserving low phase noise characteristics.
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 approach enables continuous frequency modulation over a large tuning range, enhancing frequency agility while maintaining low phase noise and high spectral efficiency, suitable for applications requiring rapid frequency changes without mode hopping.
Implementation Method 1
controlling a piezo or an electro-optical actuator configured to apply a variation of the refractive index of a resonator material through mechanical stress
Implementation Method 2
controlling a piezo or an electro-optical actuator configured to apply a variation of the refractive index of a resonator material through mechanical stress or an electric displacement field
Data Source
AI summary
A frequency agile tunable self-injection locking laser system being formed by a laser device coupled to at least one optical resonator and method and controller therefor are disclosed. A diode current and an optical resonator are controllable. A self-injection locking range is selected and the self-injection locking range corresponds an optical feedback phase for back-reflected light from the optical resonator into the laser device. A diode current is set and a maximum tuning range of the actuation voltage in which self-injection locking is maintained is determined. The laser system is operated with actuation voltages in a range depending on the determined tuning range.