Injection-Locked Laser Array With Phase Control for Low-Noise Power Scaling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-power laser systems face challenges in maintaining spectral and polarization purity when combining laser beams, leading to increased noise and instability, particularly in large arrays where mutual injection locking is difficult to stabilize and requires external optical isolators that are hard to integrate into a chip-scale solution.
Innovation Solution
A monolithically integrated optical source architecture using a seed laser and an array of secondary lasers with integrated phase shifters and couplers, where the phase of the seed laser output is adjusted for destructive interference with backward propagating light and the output of the secondary lasers is adjusted for constructive interference, eliminating the need for external optical isolators and enabling coherent beam combining with improved stability and power scaling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If discrete solid-state lasers with mutual injection locking are used, then high-power laser output is achieved, but frequency drift and instability occur due to difficulty in stabilizing mutual coupling between multiple lasers
Solution Approach 1:
The system segments the laser array into individual laser elements, each independently phase-controlled, rather than relying on mutual coupling between discrete lasers. This segmentation allows for stable high-power output while maintaining frequency stability through independent control of each element.
Solution Approach 2:
The patent implements active phase-locking control with feedback mechanisms to maintain coherent combination of laser beams. This feedback system continuously adjusts the phase of each laser element to compensate for drift, ensuring frequency stability while scaling power output.
2Reliability
If external optical isolators are used between seed laser and secondary lasers, then spectral purity is maintained, but device complexity increases and chip-scale integration becomes difficult
Solution Approach 1:
The patent merges the optical isolator function into the monolithic integrated chip structure itself, eliminating the need for separate external optical isolators. The integrated design maintains spectral purity through on-chip phase control and coherent combination, reducing device complexity and enabling chip-scale integration.
Solution Approach 2:
The system uses self-service phase control where the laser array elements actively manage their own phase relationships through integrated control mechanisms, eliminating the need for external isolators to protect spectral purity. The coherent combination process itself maintains spectral characteristics.
3Reliability
If coherent beam combining is used, then spectral and polarization purity are maintained, but noise reduction is limited compared to injection-locked arrays
Solution Approach 1:
The patent uses a master oscillator as an intermediary to injection-lock all laser elements in the array. This intermediary ensures that all elements operate at the same frequency with minimized noise, while the coherent combination process maintains spectral purity. The injection locking mechanism acts as a mediator that synchronizes phases and frequencies across the array.
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 achieves a high-power, low-noise optical source with reduced noise and increased stability, allowing for coherent combining of multiple lasers without the need for external isolators, enabling efficient power scaling and maintaining spectral purity, even in large arrays.
Implementation Method 1
the phase of the seed laser output is adjusted for destructive interference with backward propagating light and the output of the secondary lasers is adjusted for constructive interference
Data Source
AI summary
Consistent with the present disclosure, an output of a seed laser is split by a series of first coupler stages and each split portion is provided to a respective laser in an array of secondary lasers to realized injection locking of the laser array. Undesired light output from the secondary laser array back to the seed laser is monitored and the phase of such light is adjusted so that such light is subject to destructive interference and its power is minimized. Accordingly, light output from the secondary laser array back to the seed laser does not degrade the performance of the seed laser. On the other hand, light intended for output from the secondary laser array is combined through a second series of coupler stages and monitored at each stage. The phase of the output of each laser in the array is controlled to equal or be aligned with one another such that laser array outputs constructively interfere with one another. As a result, the combined output power is maximized.