Martin Divoký

Kilowatt average power 100 J-level diode pumped solid state laser

We report efficient and stable operation of the first multi-joule diode pumped solid state laser delivering 1 kW average power in 105 J, 10 ns pulses at 10 Hz, confirming the power scalability of multi-slab cryogenic gas-cooled amplifier technology.

Simple two-dimensional-imaging spectrograph with wedged narrow band filters

A minute, yet practical, modification of a well-known spectrograph based on a set of wedged narrow band filters is presented. It makes possible two-dimensional-imaging spectral measurements with a potential subpixel precision of a few micrometers. The simple spectroscopic device can evaluate dispersion of quantities which can be transformed into an image, e.g., into a spatial beam distribution. The spectrograph was used to measure angular dispersion of both a laser oscillator producing femtosecond pulses and a simple dispersive optical system, an optical wedge.

Femtosecond pulse parametric amplification at narrowband high power gas laser pumping

In ultrashort pulse amplification a narrowband gas pump pulse laser has been used for the first time. An all-stage optical parametric chirped pulse amplifier (OPCPA) was driven by a single-shot iodine photodissociation laser. For the first time a broadband amplification was achieved in potassium dihydrogen phosphate crystal at 800 nm seeding. Ti:sapphire laser pulses stretched from 12.5 fs to 250 ps were amplified and compressed to 27 fs at a 0.5 TW output power. The results suggest using narrowband high power gas lasers as OPCPA drivers to generate petawatt beams.

Broadband OPCPA pumped by ultra-narrowband gaseous iodine laser

Amplification of femtosecond pulses using an ultra-narrowband gaseous pulse laser was demonstrated for the first time. A single-shot sub-nanosecond iodine photodissociation laser with a bandwidth of 20 pm was used as a driver in an allstage OPCPA. An externally triggerable OPO tuned to laser line of 1315.24 nm was used in the front end of the iodine laser. Frequency tripled beam at 438 nm was used to pump parametric amplifiers, LBO and KDP crystals. The signal pulses from a Ti:sapphire laser at the central wavelength of 800 nm with a bandwidth of 70 nm (FWHM) were stretched from 12.5 fs to 250 ps and amplified by a factor of 2×108. The amplified pulses of typical bandwidth of 50 nm were compressed down to 27 fs. The output power of 0.5 TW was achieved. An optimized amplifier chain and addition of a third nonlinear crystal would enable to generate femtosecond pulses of several terawatts. The broadband pulses at 800 nm central wavelength were amplified in the KDP crystal for the first time, due to the suitable wavelength of the pump pulses. Availability of large aperture KDP crystals promises the generation of petawatt beam at kJ iodine laser facilities.

100J-level nanosecond pulsed Yb:YAG cryo-cooled DPSSL amplifier

We report on the successful demonstration of the world’s first kW average power, 100 Joule-class, high-energy, nanosecond pulsed diode-pumped solid-state laser (DPSSL), DiPOLE100. Results from the first long-term test for amplification will be presented; the system was operated for 1 hour with 10 ns duration pulses at 10 Hz pulse repetition rate and an average output energy of 105 J and RMS energy stability of approximately 1%. The laser system is based on scalable cryogenic gas-cooled multi-slab ceramic Yb:YAG amplifier technology. The DiPOLE100 system comprises three major sub-systems, a spatially and temporally shaped front end, a 10 J cryo-amplifier and a 100 J cryo-amplifier. The 10 J cryo-amplifier contain four Yb:YAG ceramic gain media slabs, which are diode pumped from both sides, while a multi-pass architecture configured for seven passes enables 10 J of energy to be extracted at 10 Hz. This seeds the 100 J cryo-amplifier, which contains six Yb:YAG ceramic gain media slabs with the multi-pass configured for four passes. Our future development plans for this architecture will be introduced including closed-loop pulse shaping, increased energy, higher repetition rates and picosecond operation. This laser architecture unlocks the potential for practical applications including new sources for industrial materials processing and high intensity laser matter studies as envisioned for ELI [1], HiLASE [2], and the European XFEL [3]. Alternatively, it can be used as a pump source for higher repetition rate PW-class amplifiers, which can themselves generate high-brightness secondary radiation and ion sources leading to new remote imaging and medical applications.

Characterization of Bivoj/DiPOLE 100: HiLASE 100-J/10-Hz diode pumped solid state laser

The HiLASE “Bivoj” laser system developed at CLF Rutherford Appleton Laboratory in collaboration with HiLASE team as DiPOLE100 was relocated to Dolni Brezany near Prague, Czechia at the end of 2015 and fully re-commissioned at the end of 2016. In 2016, the system demonstrated average output power of 1kW generating pulses of 105 J at 10 Hz repetition rate for the first time in the world. Since then the system has been subjected to several testing campaigns in order to determine some of its key characteristics. Beam quality, wavefront quality, pointing stability, energy stability and experience with long term operation of 1 kW laser are presented. In addition, depolarization effects have been detected inside the main amplifier. Details on these results along with numerical simulations are presented.

Commissioning of a kW-class nanosecond pulsed DPSSL operating at 105 J, 10 Hz

In this paper we present details of the commissioning of DiPOLE100, a kW-class nanosecond pulsed diode pumped solid state laser (DPSSL), at the HiLASE Centre at Dolní Břežany in the Czech Republic. The laser system, built at the Central Laser Facility (CLF), was dismantled, packaged, shipped and reassembled at HiLASE over a 12 month period by a collaborative team from the CLF and HiLASE. First operation of the laser at the end of 2016 demonstrated amplification of 10 ns pulses at 10 Hz pulse repetition rate to an energy of 105 J at 1029.5 nm, representing the world’s first kW average power, high-energy, nanosecond pulsed DPSSL. To date DiPOLE100 has been operated for over 2.5 hours at energies in excess of 100 J at 10 Hz, corresponding to nearly 105 shots, and has demonstrated long term energy stability of less than 1% RMS for continuous operation over 1 hour. This confirms the power scalability of multislab cryogenic gas-cooled amplifier technology and demonstrates its potential as a laser driver for next generation scientific, industrial, and medical applications.

Laser beam distribution system for the HiLASE Center

We report recent progress in design and testing of a distribution system for high-power laser beam delivery developed within the HiLASE project of the IOP in the Czech Republic. Laser beam distribution system is a technical system allowing safe and precise distribution of different laser beams from laboratories to several experimental stations. The unique nature of HiLASE lasers requires new approach, which makes design of the distribution system a state-of-the-art challenge.