Carrier-envelope offset stable, coherently combined ytterbium-doped fiber CPA delivering 1 kW of average power

TL;DR

This paper demonstrates a high-power, carrier-envelope offset stable ytterbium-doped fiber laser system that coherently combines beams to achieve over 1 kW average power with minimal phase noise increase.

Contribution

It introduces the first coherently combined laser system delivering both high average power and high CEO stability simultaneously.

Findings

Achieved over 1 kW average power at 80 MHz repetition rate.

Maintained CEO stability of 220 mrad rms after power amplification.

No CEO noise deterioration due to coherent beam combining.

Abstract

We present a carrier-envelope offset (CEO) stable ytterbium-doped fiber chirped-pulse amplification system employing the technology of coherent beam combining and delivering more than 1 kW of average power at a pulse repetition rate of 80 MHz. The CEO stability of the system is 220 mrad rms, characterized out-of-loop with an f-to-2f interferometer in a frequency offset range of 10 Hz to 20 MHz. The high-power amplification system boosts the average power of the CEO stable oscillator by five orders of magnitude while increasing the phase noise by only 100 mrad. No evidence of CEO noise deterioration due to coherent beam combining is found. Low-frequency CEO fluctuations at the chirped-pulse amplifier are suppressed by a slow loop feedback. To the best of our knowledge, this is the first demonstration of a coherently combined laser system delivering an outstanding average power and high CEO stability at the same time.