Coherent addition of fiber-amplified ultrashort laser pulses

Abstract

We report on a novel approach of performance scaling of ultra-fast lasers by means of coherent combination. Pulses from a single mode-locked laser are distributed to a number of spatially separated fiber amplifiers and coherently combined after amplification. Splitting and combination is achieved by polarization cubes, i.e. the approach bases on polarization combining. A Hänsch-Couillaud detector measures the polarization state at the output. The error signal (deviation from linear polarization) is used to stabilize the synchronization of different channels. In a proof-of-principle experiment the combination of two femtosecond fiber-based CPA systems is presented. A combining efficiency as high as 97% has been achieved. The technique offers a unique scaling potential and can be applied to all ultrafast amplification schemes independent of the architecture of the gain medium.

The ELI-ALPS facility: the next generation of attosecond sources

“…The beam is finally focused by a spherical mirror at almost normal incidence, located in either the auxiliary chamber CH-01.03 for phase1 or in CH-01.04 for phase2. Assuming a laser peak intensity in the gas cell of the order of -10 W cm 15 2 results in estimated focal lengths of 2.2m (phase 1) and 5.7m (phase 2). The actual focal length to be used for the XUV generation will be determined during beamline commissioning.…”

Analytical analysis of coherent combining of ultrashort laser pulses

“…Different elements have been successfully proposed such as partially reflective surfaces [9] or polarization dependent beam splitters [6]. While all of these elements can in principle just combine two beams, by cascading them, the number of channels to be combined can be increased.…”

“…In the ultrashort pulse regime, coherent combination makes it possible to scale the pulse energy, as well as the average power independently from the amplification scheme. This concept has already been demonstrated for two single mode fiber amplifiers, delivering ultrashort pulses with a combining efficiency of over 95% [6]. Additionally, by using LMA fibers, combined pulse energies of 120µJ have been already achieved [7].…”

The coherent combination of fibre lasers – Towards realistic applications

“…Previous theoretical work [1] has shown that the maximum peak power that can be extracted from a photonic crystal fibre (PCF) is of the order of 10 GW. So, to drive a wakefield, the output of many fibres need to be combined together [1,2,3]. A facility-scale, coherently-combined fibre-laser system, utilising potentially hundreds of PCFs, will generate significant cost.…”