The all-diode-pumped laser system POLARIS – an experimentalist’s tool generating ultra-high contrast pulses with high energy

Abstract

The development, the underlying technology and the current status of the fully diode-pumped solid-state laser system POLARIS is reviewed. Currently, the POLARIS system delivers 4 J energy, 144 fs long laser pulses with an ultra-high temporal contrast of 5×10 12 for the ASE, which is achieved using a so-called double chirped-pulse amplification scheme and cross-polarized wave generation pulse cleaning. By tightly focusing, the peak intensity exceeds 3.5 × 10 20 W cm −2 . These parameters predestine POLARIS as a scientific tool well suited for sophisticated experiments, as exemplified by presenting measurements of accelerated proton energies. Recently, an additional amplifier has been added to the laser chain. In the ramp-up phase, pulses from this amplifier are not yet compressed and have not yet reached the anticipated energy. Nevertheless, an output energy of 16.6 J has been achieved so far.

Generation of 25-TW Femtosecond Laser Pulses at 515 nm with Extremely High Temporal Contrast

“…A detailed description of the XPW front end, which was used at an intensity of 9 × 10 11 W/cm 2 and was operated reaching an XPW-efficiency of 13%, can be found in [22]. Six amplifiers and a nanosecond stretcher-compressor system are used to amplify and compress the laser pulses where a detailed description can be found in [10]. Additionally to the results presented in [10] we installed a beam line from the last amplifier A5 to the existing pulse compressor [23].…”

“…Six amplifiers and a nanosecond stretcher-compressor system are used to amplify and compress the laser pulses where a detailed description can be found in [10]. Additionally to the results presented in [10] we installed a beam line from the last amplifier A5 to the existing pulse compressor [23]. Here, the pulses were compressed to a full width at half maximum (FWHM) pulse duration of t pulse = 143 fs assuming a Gaussian pulse shape.…”

“…Unfortunately the amplification of high power laser pulses in reality is always associated with the amplification of unwanted noise or pre-and post-pulses on different intensity-and time-scales [8]. Since these pre-and post-pulses significantly alter the experimental conditions a lot of effort is put into improving the temporal intensity contrast [9,10]. Commonly used techniques within the laser systems are, e.g., saturable absorbers [11], or OPCPA [12], Double-CPA [13] including XPW [14].…”

“…Commonly used techniques within the laser systems are, e.g., saturable absorbers [11], or OPCPA [12], Double-CPA [13] including XPW [14]. The application of such techniques results in very high contrast laser pulses with temporal intensity contrast ratios of 10 12 or better [9,10,15]. Even those high contrast laser pulses are, however, not sufficient for some experimental applications, e.g., radiation pressure acceleration of ions [16] where a steep leading edge of the laser pulse is required for nm-scale thin targets.…”

“…In this paper we present experimental results of the second harmonic generation (SHG) of 100-TW POLARIS [10] laser pulses centered at 1030 nm wavelength and 150 fs pulse duration. Using a 2 mm thin 160 mm-diameter potassium dihydrogen phosphate (KDP) type-I SHG-crystal we achieved a maximum pulse energy of 3 J with a pulse duration of 120 fs at 515 nm center wavelength.…”