Multi-Spot End-Pumped Laser Amplifier With Telecentric Beamlet Expansion
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Solution Overview
Problem
Current ultrafast fiber lasers are limited by transversal-mode instabilities, resulting in peak power and average power constraints, and existing solutions like chirped-pulse amplification systems are complex and expensive.
Innovation Solution
A laser amplifier system utilizing multiple end pump spots with a fiber-coupled laser diode array and a telecentric telescope to magnify pump beamlets, allowing for efficient amplification without the need for multiple optical crystals or complex CPA systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If chirped-pulse amplification (CPA) with large-area photonic crystal fibers is used to achieve higher peak powers and average powers, then pulse energies beyond 1 mJ can be achieved, but system complexity and expense increase significantly
Solution Approach 1:
The pump source is segmented into multiple fiber-coupled laser diodes arranged in a specific geometric pattern, with each diode contributing to a distinct pump spot on the crystal. This segmentation allows distributed pumping that achieves high power without requiring complex CPA systems, as each diode operates independently at manageable power levels that collectively deliver the desired high peak and average power output.
2Power
If multiple diode bars are used to create a homogenized pump field over the entire crystal aperture, then higher powers can be achieved, but the pump shaping and delivery optics become complex, expensive, and bulky
Solution Approach 1:
Instead of attempting to homogenize the pump field across the entire crystal aperture with complex optics, the invention places multiple discrete pump spots at specific locations on the crystal surface. Each pump spot delivers concentrated power locally, and the collective arrangement of these spots provides uniform power distribution across the crystal without requiring complex pump shaping optics.
Solution Approach 2:
The invention transitions from a single-plane pump arrangement to a three-dimensional spatial configuration of multiple pump spots distributed across the crystal surface. This dimensional approach allows power to be delivered from multiple locations simultaneously, achieving high total power while maintaining simple optical paths for each individual pump beam.
3Power
If slab amplifiers with homogenized pump fields are used, then higher powers can be achieved, but beam quality deteriorates with high M2 values and the beam shape becomes difficult to control
Solution Approach 1:
The pump field is segmented into multiple discrete spots rather than a continuous homogenized field. This segmentation allows each pump spot to generate a clean Gaussian beam profile, and the superposition of these individual Gaussian beams maintains overall beam quality while delivering high total power, avoiding the beam degradation associated with slab amplifier homogenized fields.
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 system achieves high peak and average powers (>300 W) with excellent beam quality, reducing system complexity and cost while maintaining high performance.
Implementation Method 1
a telecentric telescope configured to magnify each individual pump beamlet and output the magnified pump beamlets such that the pump beamlets remain parallel and substantially non-divergent
Implementation Method 2
The amplifier pump signal, comprised of the multiple magnified pump beamlets, is incident on an optical crystal positioned within a resonator-like amplifier. At least one input signal is also incident on the optical crystal and is amplified by the optical crystal
Data Source
AI summary
The present application discloses various embodiments of a laser amplifier system utilizing multiple end pump spots to pump an optical crystal during the amplification process which includes a telecentric telescope configured to magnify each individual pump beamlet and output the magnified pump beamlets such that the pump beamlets remain parallel and substantially non-divergent incident on an optical crystal positioned within a resonator-like thereby permitting the construction of a compact laser amplifier system.