Suppression of the amplified spontaneous emission in chirped-pulse-amplification lasers by clean high-energy seed-pulse injection

Laser Pulse Contrast Ratio Cleaning in 100 TW Scale Ti: Sapphire Laser Systems

“…The corner cube (CC) can be set onto a second manual delay line to allow successive scans with different offset values to cover delays greater than 600 ps between the fundamental and the second harmonic. The pedestal has been studied in this way in the ns range (Fourmaux et al, 2011;Hong et al, 2005;Itatani et al, 1998). The background level limits the dynamic range over which the measurement can be achieved.…”

“…Several techniques have been proposed in order to enhance the LPCR in ultrafast CPA laser system: saturable absorbers (Hong et al, 2005;Itatani et al, 1998), double CPA laser system (Kalashnikov et al, 2005), non linear birefringence (Jullien et al, 2004), cross polarized wave generation (XPW) (Petrov et al, 2007), plasma mirror or second harmonic generation (Toth et al, 2007). Details of these techniques can be found in the cited references.…”

“…But the high intensity portion of the laser pulse will trigger a change in absorption on its rising edge, enhancing the laser pulse temporal contrast ratio for the transmitted laser pulse. This technique has been applied previously to low power laser systems (Hong et al, 2005;Itatani et al, 1998) and is now applied with 100 TW class CPA laser systems , producing an LPCR of 10 8 -10 9 . The Canadian ALLS 200 TW laser system uses such a saturable absorber to improve the LPCR before injection into the regenerative amplifier.…”

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

“…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.…”