Broad Band Transient Optical Spectroscopy System in Double-Side Laser Heating DAC

Contact: Alexander Goncharov
Location: R-140

Recently, our Carnegie group (S. McWilliams, N. Holtgrewe, and A. Goncharov) has designed and build a system to measure optical properties of materials in laser heated DAC. It consists of two parts, which operate in visible and near infrared spectral ranges. One or two fiber laser for heating are coupled to both these systems, so the optical properties, thermal emission, and Raman spectra can be studied at high temperature in the DAC using the laser heating, including pulsed and combined continuous and pulsed heating. In the visible part of the system, (12000-25000 cm -1) optical properties can be measured using an ultra-bright supercontinuum light source created by nonlinear optical processes in a photonic crystal fiber (using a Fianium 1064 nm 10 ps pulsed laser) or a SC commercial source Pegasus (Leukos). The system is equipped with spectrographs (Andor Shamrock and Acton) coupled with an intensified CCD detector (Andor) and streak camera (Sydor Ross 5100) (Fig. 3). Single shot laser heating experiments can be performed in laser heated DAC using streak camera. This system can also be used to measure thermal conductivity using a modified Angstom method via the two-side optical radiometry or thermoreflection using a continuous 532 nm laser and a photodiode connected with a fast oscilloscope. In the near IR part of the system (6000-12000 cm -1 ) spectra are measured using a grating spectrograph coupled to a multichannel array InGaAs detector (Fig. 4). This time resolved near IR BBOS system is designed to be compatible with pulsed laser heating similarly to that developed for the visible spectral range.

(Fig. 3)