Suppression of parasitic lasing in large-aperture Ti:sapphire laser amplifiers

Transverse, parasitic lasing has been observed in several large Ti:sapphire disk amplifiers. It severely limits the signal gain and the pulse energy that can be extracted from the amplifier. We have developed a technique for suppressing these parasitic lasing modes based on index matching the crystal edges with an absorbing doped polymer thermoplastic. The parasitics are completely suppressed for the range of aperture sizes and pump fluences studied here. A comparison of the amplifier performance before and after edge cladding is presented for several Ti:sapphire crystals.