Pulse contrast enhancement of high-energy pulses by use of a gas-filled hollow waveguide

Abstract

Using nonlinear ellipse rotation in a gas-filled hollow waveguide, we have increased the pulse contrast of a microjoule femtosecond laser pulse by several orders of magnitude. This scheme offers a number of advantages over competing techniques, including a high degree of tunability that allows for a broad range of input pulse parameters, higher throughput, greater stability, and an output pulse with high spatial quality that is compressible to a quarter of the original temporal width.

Generation of high contrast and high spatial quality idler from a low-gain optical parametric amplifier

“…Second, a high dynamic range third-order auto-correlator developed by the authors [19] has been used to measure the contrast of the seed and the idler pulses in the pico-second scale with 210 fs resolution. Given that the ASE level of the input pulse exceeds the 10 −5 level in the pico-second scale, figure (5) shows that the cleaning system reduces that level below the detection-threshold of the third order auto-correlator (≈ 7×10 −10 ). The high contrast ratio of the generated pulse along with the high spatial quality demonstrate the potential of the system at cleaning the front end seed of a high power laser without adding any degradation to the seed.…”

“…In addition, the amplified spontaneous emission (ASE) from regenerative amplifiers can form a long pedestal around the main pulse, contributing to the degradation of the temporal contrast. Therefore, the development of laser technologies enabling ever growing intensities has been accompanied by the development of many techniques [4][5][6][7][8][9][10][11][12] for enhancing the temporal contrast.Short pulse, low gain optical parametric amplification (OPA) is one of the most efficient contrast enhancement techniques that can work at the front end of a high power laser system. Pumping an OPA with a sufficiently short pump pulse, typically shorter than 1 ps, ensures that the pump overlaps only with the main signal pulse, leaving discrete pre-pulses and the majority of the ASE pedestal outside the amplification window.…”

“…In addition, the amplified spontaneous emission (ASE) from regenerative amplifiers can form a long pedestal around the main pulse, contributing to the degradation of the temporal contrast. Therefore, the development of laser technologies enabling ever growing intensities has been accompanied by the development of many techniques [4][5][6][7][8][9][10][11][12] for enhancing the temporal contrast.…”

Pulse fidelity in ultra-high-power (petawatt class) laser systems

“…Other contrast enhancement techniques have been used based on double optical CPA [26] , where the pulse is stretched, amplified and compressed, then passed through a nonlinear filter before being stretched again and passed to the main beamlines. A range of nonlinear filters are used, depending on the pulse duration, energy and wavelength of the system, these include hollow waveguides, birefringence, cross polarization and low-gain OPA [27][28][29][30] . These nonlinear techniques suffer from a degree of complexity in their set-up and operation as they are very sensitive to pulse-to-pulse instabilities.…”

Contrast Improvement of Relativistic Few-Cycle Light Pulses

“…-elliptical polarization rotation in air Homoelle et al (2002); Jullien et al (2004); Kalashnikov et al (2004) is based on the nonlinear induced birefringence. The efficiency is 25-50 % depending on the configuration -single vs. multi pass-and on the chirp of the input pulse and the contrast enhancement is 3-4 OOM.…”