Diode-pumped ytterbium-based chirped-pulse amplifier

Abstract

This paper will describe a comparative study on four different Yb-doped laser materials in a diode-pumped femtosecond chirped-pulse amplifier. Broadband multi-pass amplification using single crystalline Yb:CaF<inf>2</inf>, Yb:KGW, and Yb:YAG as well as Yb-doped fluoride phosphate glass was demonstrated. The seed pulses as short as 85 fs were generated in a Ti:Sapphire oscillator tuned to a center-wavelength of 1030nm and then boosted to the 100 μJ-level in a diode-pumped Yb:glass regenerative amplifier. Furthermore, the amplifier performance at nanosecond and microsecond time-scales was analyzed. With regard to the 10-nm line-width of the emission cross section the gain narrowing in Yb:YAG was investigated in particular. The pulse spectrum was narrowed to 1.9nm at a total gain of 10³ in an Yb:YAG multi-pass amplifier. This corresponds to a compressed pulse duration of 0.85 ps. When seeding with nanosecond pulses of a Q-switched oscillator a maximum pulse energy of 220mJ at a repetition rate of 10Hz has been achieved. © 2009 SPIE.