Pulse front tilt control using non-collimated beams in a single pass grating compressor.

High power laser systems based on the chirped pulse amplification (CPA) technique make use of grating pairs to compress the pulse to a short duration. When designing the pulse compressor, it is normally assumed that good beam collimation is a strong requirement in order to avoid spatio-temporal couplings. We analyze the propagation through a single pass compressor without the good collimation approximation and show that this results in a compressed pulse exhibiting pulse front tilt, whose magnitude is proportional to the normalized distance to the beam waist, providing a simple mechanism for controlling the tilt angle.

Picosecond optical parametric chirped pulse amplifier as a preamplifier to generate high-energy seed pulses for contrast enhancement.

We present the design, implementation, and testing of a novel picosecond optical parametric preamplifier system to generate high-energy seed pulses for the Vulcan laser facility. The preamplifier amplifies 100 fs pulses stretched to 3 ps pulses from 10 pJ to 70 μJ in a single stage of amplification before the pulses are further amplified in the Vulcan high-power Nd:glass laser facility to the petawatt power level. This increased seed energy has led to an improvement of the nanosecond amplified spontaneous emission contrast intensity to 10(-10) of the main pulse, without degrading the output of the laser system.