Light Source for Cavity Ring-Down Spectrometer

Cavity Ring-Down (CRD) spectroscopy is developing into a precise tool for measuring gaseous contaminants in ultrahigh vacuum and other environments. Optimum sensitivity is obtained by driving the CRD spectrometer in the mid-IR part of the spectrum with about 100 mWatts of average power at 5 kHz and with pulse lengths of 10-50 nsec. Bandwidths of 100 MHz are required. There are no commercial lasers available with these properties in a small, easy-to-use instrument Aculight proposes to use periodically poled LiNbO3 (PPLN) as the non- linear converter. A new "tandem" PPLN wavelength converter will demonstrate the narrow band wavelengths necessary for detecting H2O and O2 in Phase 1 without the need to mechanically move the nonlinear crystal or exchange the optical cavity mirror set. A single frequency device will be delivered to NIST in a Phase 2 program.