Femtosecond and Picosecond Pulsed Laser Lab
Ultrashort laser pulses are available over a wide range of wavelengths extending from the UV to the mid-IR, through a variety of lasers, nonlinear optical frequency conversion processes, and a state-of-the-art regenerative amplifier system. These short light pulses are used for time-resolved optical spectroscopy, and for nonlinear optical (NLO) spectroscopy. Time-resolved luminescence measurements are performed using a streak camera (Hamamatsu Streakscope) which allows for the parallel detection of the luminescence spectrum as a function of time (~20ps resolution). Even higher time resolution, only limited by the duration of the laser pulses (<80fs from a mode-locked Ti:sapphire laser), is achieved with "pump-probe" measurements. In such measurements, a first pulse excites the sample and a second pulse, delayed by making it traverse a longer distance, is used to probe the light-induced changes in the sample as a function of time. In NLO spectroscopy, such as second-harmonic light scattering (Hyper-Rayleigh scattering), use is made of the extremely high peak-intensities reached in these ultra-short light pulses, leading to new "nonlinear" phenomena not occurring at more usual intensities.