Abstract

With mode-locked Ti: sapphire lasers employing chirped-pulse-amplification (CPA) concept it is possible to achieve terawatt power from a table-top size system. We are now constructing the Table-top Ten TW Ten-Hz Tunable Ti:sapphire laser, which is named T⁶ laser. In standard TW laser systems, the amplification of a single pulse from the oscillator (several nJ energy) to the mJ level is usually done by either a regenerative amplifier or by a multipass preamplifier with a rather high number of passes. In order to install into the T⁶ laser, we have developed a simplified preamplifier that has only three passes in a crystal. The optical set-up of the pre-amplifier is a confocal arrangement of two f = 1000 mm focusing mirrors with the Ti:sapphire crystal located at the beam waist. After the first pass through the amplifier the beam path is reversed by a comer-cube retroreflector towards the second pass, after which a roof-top retroreflector reverts the beam to the final third pass. After that a pick-up mirror reflects the pulse out of the preamplifier. To have the beam waist of each consecutive pass located at the crystal, and to have the beam paths cross each other within the crystal, the input beam is required to have a beam waist at the first confocal mirror, while the diameter of this beam waist determines the beam waist at the Ti:sapphire crystal. Both is accomplished by controlling the alignment of the Galileian telescope and by the choice of the demagnification.

© 1995 IEEE