High power single frequency source for cavity ring-down spectroscopy

Aculight proposes to develop a laser source that will enable NIST to perform highly sensitive water vapor detection via cavity ring-down spectroscopy. The source will operate over a wavelength region centered at 1380nm. It will be based upon frequency conversion of a single frequency fiber source using an optical parametric oscillator (OPO).The performance of the source in terms of several critical parameters (linewidth, power output) will substantially exceed that of alternate sources such as external cavity diode lasers (ECDLs). In particular, ECDLs are commercially unavailable at this wavelength. The proposal will take advantage of previous work performed at Aculight for NIST, which demonstrated single frequency operation of an OPO pumped by a low power diode laser. The fiber-pumped device proposed here will display two orders of magnitude greater output power and will allow much greater control of output frequency. In Phase 1, Aculight will demonstrate all the NIST specifications and in Phase 2 deliver a package source for use in CRDS at NIST. We anticipate that it will be straightforward to extend this technology to other wavelengths between 1 and 4?m, which will make possible detection of other species by the ring-down method.