Diode-pumped lasers for ultrashort pulse amplifiers (diomede)
Ultraintense laser driven sources of high energy particle and radiation are developing rapidly and are being considered for medical applications. In this scenario it is crucial to rely on affordable, scalable and reliable laser systems capable of delivering pulses of up to 10E15 W peak power with kW average power. These parameters call for high wall-plug efficiency laser systems. Currently available ultraintense lasers use flashlamps as primary energy sources to pump lasing media, making the systems very inefficient, with wall-plug efficiency typically around 0.1%. These constraints limit the size and the repetition rate of current laser systems. Diode pumping is an alternative to flashlamp pumping and can lead to much greater overall efficiencies. The idea is therefore to develop new schemes for pumping ultraintense lasers with higher efficiency. Our scheme uses Yb:YAG as a lasing material, possibly shaped and customized using ceramics. Yb:YAG has a long life-time, around 1 ms, and can be pumped at 940 nm, a typical wavelength for commercial laser diodes. The final result aimed for is diode-pumped Yb:YAG amplifier lasing at 1030 nm and producing up to 10 J. Once frequency doubled, this system could be used to pump Ti:Sa based ultraintense lasers. A petawatt Ti:Sa laser system could therefore use four of these units for a total of 20 J at 515 nm in the final power amplifier. the overall wall-plug efficiency of such a system would exceed 10%, more that two orders of magnitude higher than current limits. In this framework, we are developing numerical models and exploring new materials to design a complete diode-pumped system capable of satisfying the kW average power requirements of medical applications of a petawatt femtosecond laser system.