Ultrafast Laser System

  • The Ultrafast Laser system is capable of carrying out Transient Absorption and Fluorescence Up-conversion experiments. The Transient Absorption Laser System: Spitfire Ti:Sapphire regenerative ultrafast amplifier system delivers 120 fs pulses in the wavelength range of 780-120 nm with an average pulse/energy of 4mJ at a repetition rate of 1KHz. Further, output of the regenerative amplifier is coupled to Optical Parametric Amplifier, TOPAS to extend the wavelength tunability from 400-2000nm.The Fluorescence Up-conversion Laser System: Fluorescence Up-conversion, also known as fluorescence sum frequency generation, works on the principle of frequency mixing of fluorescence, originating from a fluorescent molecule upon excitation by an ultra-short pump pulse, with another ultra-short probe laser pulse. The fundamental for the Up-conversion is taken from MAITAI laser (Spectra Physics, ~120 fs, 80 MHz, 2.5 W at 800 nm) can be frequency doubled and is used to excite the sample and the frequency mixing is performed in a non-linear optical crystal, e.g. BBO (β-Borium Borate). The time evolution of the fluorescence is obtained by delaying the probe pulse using a mechanical delay stage. This technique of Fluorescence Up-conversion is used to study photo-physical properties of excited states.