Coherent combining of ultrashort fiber-amplified laser pulses

We report on a novel concept to scale the performance 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. The splitting and combination process is based on the polarization combining technique using polarization cubes. A Hänsch-Couillaud detector measures the polarization state of the combined beam. The error signal (deviation from linear polarization) is used to stabilize the optical path lengths in the different channels with a piezo mounted mirror. In a proof-of-principle experiment the combination of two femtosecond fiber-based amplifiers in a CPA systems is presented. A combining efficiency as high as 97% has been achieved. Additional measurements were carried out to investigate the stability of the system. The concept offers a unique scaling potential and can be applied to all ultrafast amplification schemes independent of the architecture of the gain medium

Fiber laser CPA system delivering 120 j femtosecond pulses using coherent combining

We report on the coherent combination of two chirped pulsed fiber amplifiers using a polarization cube. Femtosecond pulses were combined with an efficiency of 91% obtaining a combined pulse energy of 120 J

Coherently combined fiber laser system delivering 120 µJ femtosecond pulses

We report on the coherent combination of two chirped pulsed fiber lasers. The beams coming from two 100 µm core diameter ytterbium-doped rod-type fibers were coupled in a Mach-Zehnder-type interferometer by means of a polarization beam splitter. Active stabilization of the interferometer was achieved by using a piezo-mounted mirror driven by a Hänsch-Couillaud polarization detection system. Pulses with 120 µJ energy and a compressed duration of 800 fs were obtained. This, compared with the 66 µJ coming from each single amplifier, results in a combining efficiency as high as 91%

High average and peak power few-cycle laser pulses delivered by fiber pumped OPCPA system

We report on a high power optical parametric amplifier delivering 8 fs pulses with 6 GW peak power. The system is pumped by a fiber amplifier and operated at 96 kHz repetition rate. The average output power is as high as 6.7 W, which is the highest average power few-cycle pulse laser reported so far. When stabilizing the seed oscillator, the system delivered carrier-envelop phase stable laser pulses. Furthermore, high harmonic generation up to the 33th order (21.8 nm) is demonstrated in a Krypton gas jet. In addition, the scalability of the presented laser system is discussed