Tunable femtosecond pulses in 375–405 nm region with Ti: sapphire oscillator by chirped sum frequency

We report the generation of tunable pulses near 390�nm region with nJ pulse energies of femtosecond (fs) Ti: Sapphire oscillator. The tunable pulses have been generated by sum frequency mixing between the chirped and the unchirped fundamental pulses at 775�nm at 82�MHz at 200�mW average power levels. To estimate the pulse durations in UV, the fundamental pulse has been characterized by the spectral phase interferrometry for direct electric filed reconstruction (SPIDER) by modifying the same set up. The output power and the pulse widths have been estimated. � 2014, The Optical Society of India.