Yb:YAG Innoslab amplifier: efficient high repetition rate subpicosecond pumping system for optical parametric chirped pulse amplification

Abstract

We report on a Yb:YAG Innoslab laser amplifier system for generation of subpicsecond high energy pump pulses for optical parametric chirped pulse amplification (OPCPA) at high repetition rates. Pulse energies of up to 20 mJ (at 12:5 kHz) and repetition rates of up to 100 kHz were attained with pulse durations of 830 fs and average power in excess of 200 W. We further investigate the possibility to use subpicosecond pulses to derive a stable continuum in a YAG crystal for OPCPA seeding. © 2011 Optical Society of America OCIS codes: 140.4480, 190.4410, 190.4970. High repetition rate free electron lasers (FELs) [1], attosecond metrology [2], and coherent control [3] are examples of applied physics fields that require stable laser amplifier systems with very high repetition rates, high pulse energies, and ultrashort pulse durations. Free electron lasers such as FLASH would tremendously benefit when combining extreme UV (XUV) pulses and a laser amplifier with millijoule-level pulse energies, 5-20 fs pulse duration, and an intraburst repetition rate of 0:1-1 MHz to perform pump-probe experiments. Another application is the FEL seeding with similar pulse parameters [4]. Such a state-of-the-art laser system is difficult to develop, most of all because of the additional longterm stability requirements for operation at large scale facilities [5]. Optical parametric chirped pulse amplification (OPCPA) [6,7] is to date the only technique to offer a way to amplify broadband pulses at high pulse energies with several hundreds of watts average power level. An increase of the average output power of an OPCPA system requires novel concepts for the pump amplifier system. Experimental OPCPA pump amplifiers have been successfully used, either to amplify pulses at low repetition rates and high peak powers [8,9] or high repetition rates and lower pulse energies [10,11]. An avenue in the multikilohertz repetition rate regime is the regenerative thin-disk amplifier that can provide millijoule pulse energy in the picosecond regime [12]. The concept has its limitations at high average powers given by difficult cavity outcoupling. Fiber chirped pulse amplification (CPA) laser amplifiers have emerged to be powerful tools for amplification to highest average powers of up to 830 W at femtosecond pulse durations [13,14]. However, combining the fiber laser amplifier with a Yb:YAG Innoslab amplifier [15] is a promising approach to push the average power beyond the kilowatt level with multimilljoule pulse energies. A striking advantage of this amplifier combination is the attainable subpicosecond pulse duration, avoiding complicated and lossy stretcher-compressor schemes for OPCPA [16]. Recent developments have also shown the potential to use a subpicosend pump amplifier driven continuum [17] generated in bulk media to seed optical parametric amplification (OPA) [18]. Additionally, higher peak intensities can be used to drive the OPCPA system due to the inherent scaling of the damage threshold with shorter pulse duration [19]. The current st...

Ultrafast supercontinuum generation in bulk condensed media

“…Indeed, the availability of picosecond pulse-generated SC with a well-behaved spectral phase that is compressible down to transform-limit paved new avenues in the development of picosecond-laser pumped noncollinear optical parametric amplifiers [213] and of a whole new generation of compact SC-seeded OPCPA systems. These systems are built around amplified solely sub-picosecond and picosecond lasers, such as Yb:KYW [214], Yb:YAG [51,207,[215][216][217] and Yb-fibre [218,219], and are designed to provide few optical cycle pulses in the near-and mid-infrared at very high repetition rates. Finally, picosecond SC serves as a seed signal in the mid-infrared optical parametric amplifiers driven by amplified picosecond Ho:YAG lasers [220,221].…”

“…Recently developed high repetition rate SC-seeded OPCPA systems provide intense few optical cycle pulses with high average power at high repetition rate [50]. SC generation in laser host crystals with sub-picosecond and picosecond laser pulses paved a new avenue in the development of compact OPCPA systems, which are built around sole picosecond oscillator/amplifier systems [51]. Finally, the SC-seeded OPCPA system delivering carrier-envelope phase-stable few-optical-cycle pulses with high average and ultrahigh peak power has been recently demonstrated [52].…”

Yb:YAG single crystal fiber power amplifier for femtosecond sources

“…Although it requires quite complex systems, the slab geometry has proven to be a very successful approach. Up to 1.1 kW [5] average power and 20 mJ [6] energy were obtained with an Yb:YAG Innoslab amplifier. Significant improvement of the emission cross section and the thermal conductivity can be observed at cryogenic temperatures in most Ybdoped crystals.…”

Diode-Pumped High Energy and High Average Power All-Solid-State Picosecond Amplifier Systems

“…A 1-kHz-repetition-rate thin-disk regenerative amplifier was reported with a pulse energy of 10 mJ and a pulse duration of 1.29 ps after compression [5,17]. With innoslab and fiber materials, an average power of 250 W at 12.5 kHz was obtained, and 97 W average output power at 5.47 MHz picosecond pulses was generated from a fiber master oscillator power amplifier (MOPA) system, respectively [18,19]. Combining some of the different technologies mentioned above, a hybrid CPA laser system was reported recently.…”