We explore how DiPOLE-type laser systems, based on cryocooled, diode pumped, multi-slab Yb:YAG amplifier technology, can be adapted for direct-CPA ps-pulse generation, opening up the possibility of producing pulses with 10s of TW of peak power, 10s of J of energy, at the kW average power level, without having to resort to more complex and less efficient schemes like OPCPA or Ti:Sapphire amplifier chains. Initial calculations indicate that the narrow gain-bandwidth of cryo-cooled Yb:YAG is challenging in terms of stretching and recompression of the laser pulses, but nonetheless should allow the generation of 2 ps pulses at nearly the same energy and at the same repetition rate as in ns mode.

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.

HiLASE facility focuses on development of high average power pulsed lasers with picosecond and nanosecond laser pulses. Recently, lasers with 500 W average power with picosecond pulses and energy of 5 mJ and 1 kW average power with nanosecond pulses and energy of 100 J were reported. Current status and future plans of the HiLASE facility are presented.

In this paper, we review the development, at the STFC's Central Laser Facility (CLF), of high energy, high repetition rate diode-pumped solid-state laser (DPSSL) systems based on cryogenically-cooled multi-slab ceramic Yb:YAG. Up to date, two systems have been completed, namely the DiPOLE prototype and the DiPOLE100 system. The DiPOLE prototype has demonstrated amplification of nanosecond pulses in excess of 10 J at 10 Hz repetition rate with an optical-to-optical efficiency of 22%. The larger scale DiPOLE100 system, designed to deliver 100J temporally-shaped nanosecond pulses at 10 Hz repetition rate, has been developed at the CLF for the HiLASE project in the Czech Republic. Recent experiments conducted on the DiPOLE100 system demonstrated the energy scalability of the DiPOLE concept to the 100 J pulse energy level. Furthermore, second harmonic generation experiments carried out on the DiPOLE prototype confirmed the suitability of DiPOLE-based systems for pumping high repetition rate PW-class laser systems based on Ti:sapphire or optical parametric chirped pulse amplification (OPCPA) technology.

Laser systems efficiently generating nanosecond pules at kJ energy levels and at multi-Hz repetition rates are required in order to translate laser-plasma interactions into practical applications. We have developed a scalable, actively-cooled diode-pumped solid state laser amplifier design based on a multi-slab ceramic Yb:YAG architecture called DiPOLE (Diode-Pumped Optical Laser for Experiments) capable of meeting such requirements. We demonstrated 10.8 J, 10 Hz operation at 1030 nm using a scaled-down prototype, reaching an optical-to-optical efficiency of 22.5%. Preliminary results from a larger scale version, delivering 100 J pulse energy at 10 Hz, are also presented.

The goal of the HiLASE project is to design and optimize parameters for 100 J/10 Hz Yb:YAG laser amplifiers that are scalable to the kJ regime. The HiLASE power amplifier design is based on a cryogenic, gas-cooled multi-slab concept. Simulation results of the 10 J pre-amplifier agree very well with experimental measurements. In order to fulfil the very demanding requirements, which include wall-plug efficiency > 12% and repetition rates up to 10 Hz, HiLASE and RAL teams are closely working together and developing the approach described here.

In this paper we describe the progress of energy scaling cryogenic gas-cooled Yb:YAG amplifier technology from a 10 J, 10 Hz prototype to delivering 100 J pulses at 1 Hz. The architecture of the prototype system (DiPOLE) is presented, highlighting the key design characteristics that enable energy scaling, along with the improvements that have allowed development of a 100J-level system (DiPOLE100).

In this paper we review the provision of the laser diagnostics that are installed on the Vulcan laser facility. We will present strategies for dealing with the energy of high energy systems and with ways of handling the beam sizes of the lasers. We present data captured during typical experimental campaigns to demonstrate their reliability and variation in shot to shot values.

In this paper we present details of a scalable design for a cryogenic helium gas cooled DPSSL amplifier based on a multislab Yb:YAG geometry. A prototype amplifier design capable of efficient amplification of 10 ns pulses to 10 J at 10 Hz is presented, which has been derived from computational fluid dynamic calculations and thermal modeling. Model predictions have also been used to design a suitable cryogenic gas cooling system, details of which are also presented. Experimental testing has confirmed stable amplifier temperatures are achievable from room temperature down to 88 K, with a gas coolant temperature stability of +/- 0.2 K. Single-pass transmission wave front measurements are in reasonable agreement with model predictions derived from thermal maps for two different YAG slab geometries. Slabs with a narrower width Cr-doped YAG absorptive cladding, added to suppress ASE, demonstrated a wave front error of similar to 0.2 waves at 1030 nm (peak-to-valley) over the 20 mm x 20 mm pumped region within the amplifier. The low level of optical distortion confirms that the amplifier design provides an acceptable level of temperature and flow uniformity and demonstrates the merit of a multislab geometry. (C) 2015 Optical Society of America

An overview of Czech national R&D project HiLASE (High average power pulsed LASEr) is presented. The HiLASE project aims at development of pulsed DPSSL for hi-tech industrial applications. HiLASE will be a user oriented facility with several laser systems with output parameters ranging from a few picosecond pulses with energy of 5 mJ to 0.5 J and repetition rate of 1-100 kHz (based on thin disk technology) to systems with 100 J output energy in nanosecond pulses with repetition rate of 10 Hz (based on multi-slab technology).

We present results for a 150 mJ, 10 Hz, ns front end system for a 100 J DPSSL. The system incorporates arbitrary temporal pulse shaping, in addition to passive and active spatial shaping of the output.

An overview of the Czech national R&D project HiLASE (High average power pulsed laser) is presented. The project focuses on the development of advanced high repetition rate, diode pumped solid state laser (DPSSL) systems with energies in the range from mJ to 100 J and repetition rates in the range from 10 Hz to 100 kHz. Some applications of these lasers in research and hi-tech industry are also presented.

We present calculations and results for frequency doubling on DiPOLE, a 7J 10 Hz Yb:YAG DPSSL, using DKDP, YCOB and LBO. The LBO crystal achieved the highest conversion efficiency of 65%.

kJ-class DPSSL systems with multi-Hz repetition rate for IFE and other laser-plasma based applications require an amplifier architecture with high efficiency and high gain. We present a concept based on cryogenically cooled ceramic Yb:YAG.

We present the latest results for DiPOLE, a cryogenic gas cooled multi-slab Yb:YAG DPSSL amplifier, demonstrating 7.4 J at 10 Hz.

DiPOLE is a programme for the development of DPSSL systems producing ns-pulses up to the kJ-level at multi-Hz repetition rates. The chosen concept and results from a first prototype will be reviewed.

We present recent amplification results for DiPOLE, a cryogenic gas cooled multi-slab Yb:YAG amplifier, demonstrating efficient operation with pulse energies of 10.1 J at 1 Hz and 6.4 J at 10 Hz.

We present preliminary amplification results for the DiPOLE cryogenic gas cooled multi-slab ceramic Yb:YAG amplifier over a range of temperatures from 88 to 175K using a temporary bow-tie multi-pass extraction architecture.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text P. J. Phillips, C. Hernandez-Gomez, I. Musgrave, and J. Collier, "Two beam spatial phasing with a CW laser," in Frontiers in Optics 2011/Laser Science XXVII, OSA Technical Digest (Optica Publishing Group, 2011), paper FWZ5. Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

One of the biggest challenges the HiPER project is facing is to identify a laser architecture that meets all the demanding requirements. Among those are high wall-plug efficiency (15 to 20%) and repetition rate (5 to 10 Hz). In order to perform this task, four teams from the co-authors' institutions are working together and exploring several approaches described here.