The amplified titanium sapphire system for investigating ultrafast processes in condensed matter systems
The amplified titanium sapphire system for investigating ultrafast processes in condensed matter systems

Function
Supports a broad range of basic and applied research that includes understanding primary photophysical processes in molecules, molecular films, and supramolecular systems; characterizing the low-frequency (terahertz) vibrational response of molecules; and simulating the effects of space radiation with state-of-the-art microelectronic circuitry. The Ultrafast Laser Facility (ULF) supports NRL research programs and collaborative research projects with outside universities, industry, and government institutions. Customers from the space electronics industry use the ULF as a tool to optimize circuit designs for space applications.

Description
The ULF's equipment has recently been used to perform experiments that measure ultrafast photophysical processes on organic macromolecules and in organic solid state thin films designed for photonics applications. An optical apparatus has been configured to characterize photophysical mechanisms using transient pump-probe spectroscopy at either a single frequency or using a multicolor continuum. A separate apparatus is used to measure the picosecond timescale photo-induced emission process following ultrashort pulse excitation. An ultrafast terahertz spectrometer is under construction, which will be used to measure the low-frequency vibrational response of organic solids and liquids. The ULF is also devoted to understanding the effects of space radiation on microelectronics circuitry. Sub-picosecond laser pulses are used to simulate the interaction of space radiation with semiconductor material (Si, GaAs, InAs, etc.). The ultrafast pulsed laser permits the study of space radiation effects in microelectronics in a highly controlled manner, and thus complements experiments performed at accelerator facilities. The ULF has proven invaluable to the space industry for troubleshooting microelectronic circuits for space applications.

Instrumentation
The ULF contains laser systems capable of producing laser pulses in a temporal range between 20 fs and 2 ps. The core femtosecond system consists of an amplified titanium sapphire laser that is coupled to two tunable optical parametric amplifiers. This system generates tunable femtosecond pulses from the mid-infrared to the ultraviolet part of the spectrum. A second titanium sapphire oscillator is available for applications requiring high laser pulse repetition rates. The ULF also maintains a synchronously pumped cavity-dumped dye laser system, which produces picosecond laser pulses in the visible. A time-correlated single photon counting apparatus provides a sensitive measurement of fluorescence signals. The ULF contains the optical apparatus and spectroscopic instrumentation to perform a wide variety of ultrafast experiments.