C.B. Edwards

High contrast multi-terawatt pulse generation using chirped pulse amplification on the VULCAN laser facility

High power (8 TW), ultra-short (2.4 ps), pulses have been generated using chirped pulse amplification techniques on the VULCAN Nd: glass laser. A novel oscillator was developed as a driver producing ≈ ps pulses at 105 nm. The oscillator output was stretched prior to amplification and compressed at an aperture of 150 mm. The contrast ratio obtained was ≈ 106, which is suitable for laser plasma interaction studies.

Well characterized 1019W cm2 operation of VULCAN—an ultra-high power Nd:glass laser

Abstract Peak intensities of 1019 W cm2 have been reliably obtained from a high power Nd:glass laser using chirped pulse amplification. An Additive Pulse Modelocked oscillator incorporating diode pumped Nd:LMA was used to generate the sub-picosecond pulse. The focal spot intensity distribution has been characterized in detail showing a three times diffraction limited beam.

100 J-level nanosecond pulsed diode pumped solid state laser

We report on the successful demonstration of a 100 J-level, diode pumped solid state laser based on cryogenic gas cooled, multi-slab ceramic Yb:YAG amplifier technology. When operated at 175 K, the system delivered a pulse energy of 107 J at a 1 Hz repetition rate and 10 ns pulse duration, pumped by 506 J of diode energy at 940 nm, corresponding to an optical-to-optical efficiency of 21%. To the best of our knowledge, this represents the highest energy obtained from a nanosecond pulsed diode pumped solid state laser. This demonstration confirms the energy scalability of the diode pumped optical laser for experiments laser architecture.

Titania—a 1020 W cm−2 ultraviolet laser

The Titania laser system, based around a 42 cm e-beam pumped KrF amplifier, is currently being installed at the Rutherford Appleton Laboratory and will come on line as a user facility in 1996. Like Sprite, its predecessor, it will operate in both CPA (249 nm) and Raman (268 nm) short-pulse modes, delivering up to 10 TW to target in high-quality beams. With brightness expected to reach 10 21 W cm -2 sterad -1 , it will be the worlds brightest ultraviolet laser. The design of the Titania system includes a number of novel features. The multi-pass Ti :sapphire front-end amplifier uses an unusual beam-folding scheme. The Raman system will involve the first application of Raman multiplexing, combining high KrF efficiency with low transport cost. Reflective coatings with very high damage thresholds are being developed for the CPA compressor gratings and the UV transport optics. A windowless configuration for the final Raman amplifier is presently under analysis, to allow the performance of this maximally stressed component to be extended substantially. Finally the design of the Titania e-beam machine, featuring novel split-cathode diodes, has resulted in unusually high efficiency of electron transport into the laser gas. The lasers infrastructure has involved sophisticated mechanical and electrical design, and a computerized diagnostic, control and safety package is being developed to allow one-man operation of the whole 1000 m 2 installation.

ELI-Beamlines: development of next generation short-pulse laser systems

Overview of the laser systems being built for ELI-Beamlines is presented. The facility will make available high-brightness multi-TW ultrashort laser pulses at kHz repetition rate, PW 10 Hz repetition rate pulses, and kilojoule nanosecond pulses for generation of 10 PW peak power. The lasers will extensively employ the emerging technology of diode-pumped solid-state lasers (DPSSL) to pump OPCPA and Ti:sapphire broadband amplifiers. These systems will provide the user community with cutting-edge laser resources for programmatic research in generation and applications of high-intensity X-ray sources, in particle acceleration, and in dense-plasma and high-field physics.

Wave-front control of a large-aperture laser system by use of a static phase corrector

In large-aperture, ultrahigh-intensity laser systems, such as Vulcan at the Rutherford Appleton Laboratory, one of the most important factors that determines the ultimate on-target focused intensity is the wave-front quality of the laser pulse. We report on a wave-front analysis carried out on Vulcan to determine the nature and contribution of the aberrations present in the laser pulse that effectively limited the available on-target intensity. We also report on a significant improvement to the wave-front quality that was achieved by static correction of the main aberration, resulting in an increase of focused intensities by a factor of 4.

Self-starting additive-pulse mode locking of a Nd:LMA laser.

A Ti:sapphire-pumped Nd:LMA laser has been passively mode locked by using additive-pulse mode locking, which generates 600-fs-duration pulses at 1.054-µm. The wavelength, pulse duration, and long-term stability of the laser make it eminently suitable as a front-end oscillator of a high-power, chirped-pulse amplifier experiment based on 1.053-µm amplification in Nd:phosphate glass.

High energy, high repetition rate, second harmonic generation in large aperture DKDP, YCOB, and LBO crystals

We report on type-I phase-matched second harmonic generation (SHG) in three nonlinear crystals: DKDP (98% deuteration), YCOB (XZ plane), and LBO (XY plane), of 8 J, 10 Hz cryogenic gas cooled Yb:YAG laser operating at 1029.5 nm. DKDP exhibited an efficiency of 45% at a peak fundamental intensity of 0.24 GW/cm2 for 10 Hz operation at 10 ns. At the same intensity and repetition rate, YCOB and LBO showed 50% and 65% conversion efficiencies, respectively. Significant improvement in conversion efficiency, to a maximum of 82%, was demonstrated in LBO at 0.7 GW/cm2 and 10 Hz, generating output energy of 5.6 J at 514.75 nm, without damage or degradation. However, no improvement in conversion efficiency was recorded for YCOB at this increased intensity. Additionally, we present theoretically calculated temperature maps for both 10 J and 100 J operation at 10 Hz, and discuss the suitability of these three crystals for frequency conversion of a 100 J, 10 Hz diode pumped solid state laser (DPSSL).

Diode-pumped picosecond Nd:YLF laser oscillator at 1053 nm

Abstract A cw diode-pumped, compact and efficient Nd:YLF laser producing stable picosecond pulses at 1053 nm has been developed as a source for a multi-terawatt laser.

Single shot beam quality (M2) measurement using a spatial Fourier transform of the near field

Abstract A new method to determine the M 2 number in a single shot measurement is proposed and examples are given. The M 2 is calculated using a Fourier transform of the spatial phase- and amplitude-distribution in the near field. The measurements are done with a radial shear interferometer. The method is easily applicable to a wide variety of lasers (IR-UV) from CW to sub-picosecond pulsed operation.