Speaker
Description
Fiber lasers have outstanding features including power handling, efficiency, and beam quality. Spatial and temporal combination of ultrafast fiber lasers provides pulse energy and power scaling (up to 10 J, 100 kW), a promising solution for driving next-generation kilohertz plasma accelerators and their secondary radiation sources, as well as for enabling new capabilities in beam diagnostics, manipulation, and electron removal for radiofrequency accelerators. We are building an architecture that integrates coherent pulse combining in space, time, and spectrum simultaneously, which also provides pulse duration reduction (to as short as 30-40 fs) besides energy/power scaling, critical to applications requiring short pulses (e.g. plasma acceleration).
Here we present the design and development progress of a multidimensionally combined fiber laser that will deliver 150 mJ energy, 40 fs duration, 5 kHz rep-rate, 1 kW average-power pulses, including overcoming challenges due to broad bandwidth in seeding, amplification, gain narrowing/saturation, combining, dispersion and compression.
We completed the system frontend and a high power amplification chain, where laser pulses are burst-modulated, spectrally broadened, stretched, split into three spectral channels, and amplified through multiple single-mode and large-core Yb fiber amplifiers with distributed spectral filtering. Programmable pulse shaping was implemented in each spectral channel, and its feedback optimization was achieved. We developed record large core (85 µm) monolithically integrated fiber amplifiers, and demonstrated record energy amplification (8 mJ) from a monolithically integrated amplifier. In each spectral channel, we will further install a final array of 9 high power fiber amplifiers (the same as the existing type tested at 8 mJ).
In proof-of-principle tests, we demonstrated record short pulses (42 fs) from spectrally combined Yb fiber lasers and record broad bandwidth (supporting ~50 fs) in temporal stacking 10 fiber-amplified laser pulses. An FPGA-based control system has been implemented in the 150 mJ system for laser and combining controls, and machine protection. After the final fiber amplifier arrays are installed, the amplified pulses will be sequentially combined by a diffractive spatial combiner, a dichroic-optic spectral combiner, and a cascaded-cavity temporal stacker, all being fabricated, and finally compressed by an out-of-plane, multilayer dielectric grating compressor.
This work is supported by DOE Office of Science HEP and ARDAP, and Moore Foundation.
| Working group | WG1 |
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