DEPARTMENT OF LIFE AND PHYSICAL SCIENCES

Optical and Laser Systems

Research Facilities

OPTICAL AND LASER SYSTEMS

Dr, Balasubramanian's lab has a Spectra Physics Ti-Sapphire laser system that is pumped by a Spectra Physics Millenia Pro laser. The Spectra-Physics Model 3900S is a high-performance, tunable, solid state IR laser. It delivers tunable, CW output from 675 to 1100 nm in a low-cost package. Pumped with 532 nm diode-pumped Millenia solid state laser, the Model 3900S solid state Ti-Sapphire laser produces up to 3.5 W of TEM00 output for the broadest range of IR applications.The laser is computer controlled and data acquisition is done using lockin amplifier techniques using LabView.

For time-dependent laser spectroscopy Dr. Balasubramanian's lab also has a diode-pumped Quantronix Hawk II laser system with a peak pulse energy of 15 mJ and a pulse-width of around 75 ns. This laser has a lasing wavelength at 1064 nm and a doubled first harmonic at 532 nm. Pump-probe experiments can be done using this system in the doubled mode. Most material systems will absorb the 532 nm light and use it as an excitation wavelength.

In addition diode laser systems are also available for specfic wavelengths throughout the visible and near-IR part of the spectrum (400 - 1100 nm). These are temperature tunable over short bandwidths. There are also a variety of He-Ne and fixed wavelength diode laser modules available.

Broadband white light sources used in tandem with sensitive spectrometers give us the capability to look at optical processes across a wide bandwidth.

DETECTION AND ELECTRONICS

Detection is done using fast silicon and germanium photodetectors and CCD cameras. Wavelength filtering can be done using sophisticated Acton SP2150 spectrometer with a wavelength selectivity of 0.25 nm or better. Stanford research system lockin amplifiers are used to measure weak signals. Laser modulation can be done at any frequency and a suitable lockin amplifier can be used in detection. We have the capability to do GHz as well as MHz waveform analysis and capture as a function of time using Tektronix oscilloscopes. Automation is achieved by multiple computer platforms and LabView.

FABRICATION AND CHEMICAL SYNTHESIS

Thinfilm sample fabrication facilities including micro-mechanical polishing and chemical etching are available. Nanoparticle synthesis capabilities are available in Dr. Afrasiabi's lab.