Intracavity laser absorption measurements at ultrahigh spectral resolution.

Intracavity laser absorption spectroscopy with ultrahigh sensitivity and enhanced spectral resolution is demonstrated. It entails use of an intracavity étalon that selects equally spaced modes of the cavity. These modes are reduced in intensity when they occur at spectral locations where absorption that is due to intracavity species also occurs. We obtained absorption spectra by tuning the étalon in small steps across its free spectral range, recording intracavity spectra at each step, and summing the result. The maximum resolution is determined by the width of the étalon peaks, which was ~0.01 cm(-1). When the finesse of the étalon is increased, the resolution equal to the width of a single laser mode can be achieved. With this technique, spectra at Doppler-free resolution such as that required for studies of high vibrational-overtone transitions of molecules in supersonic jets are possible.

[1]  F. Stoeckel,et al.  Time-resolved intracavity laser spectroscopy: 266 nm photodissociation of acetaldehyde vapor to form HCO , 1985 .

[2]  F. Stoeckel,et al.  Jet cooled NO2 intra cavity laser absorption spectroscopy (ICLAS) between 11200 and 16150 cm−1 , 1995 .

[3]  J. O'Brien,et al.  Laboratory measurements of absorption coefficients for the 727 nm band of methane at 77 K and comparison with results derived from spectra of the Giant planets , 1995 .

[4]  G. Gaida,et al.  Quantum fluctuations of a multi-mode laser oscillator , 1981 .

[5]  Beck,et al.  Transition from quantum-noise-driven dynamics to deterministic dynamics in a multimode laser. , 1989, Physical review. A, General physics.

[6]  F. Stoeckel,et al.  Intracavity laser spectroscopy with vibronic solid-state lasers: II. Influence of the nonlinear mode coupling on the maximum sensitivity of a Ti:sapphire laser , 1995 .

[7]  John U. White.  Very long optical paths in air , 1976 .

[8]  J. Trauger,et al.  High Resolution infrared spectra , 1990 .

[9]  F. Stoeckel,et al.  Intracavity-laser-absorption spectroscopy of the visible overtone transition of methane in a supersonically cooled jet , 1991 .

[10]  O. Sarkisov,et al.  New Spectroscopic Methods in Gas-Phase Chemical Kinetics , 1985 .

[11]  A. Kachanov,et al.  Parasitic selection in intracavity laser detection spectroscopy , 1982 .

[12]  S. Cheskis.  Intracavity laser absorption spectroscopy detection of HCO radicals in atmospheric pressure hydrocarbon flames , 1995 .

[13]  S. A. Kovalenko,et al.  Nonlinear dynamics of a multimode dye laser with an adjustable resonator dispersion and implications for the sensitivity of in-resonator laser spectroscopy , 1992 .

[14]  James J. O'Brien,et al.  Measurement of pressure-broadening and lineshift coefficients at 77 and 296 K of methane lines in the 727 nm band using intracavity laser spectroscopy , 1994 .

[15]  F. Stoeckel,et al.  Temperature measurement of atomic hydrogen produced by hot-filament dissociation in a CH4H2 mixture , 1993 .

[16]  F. Stoeckel,et al.  Intensity measurements and self-broadening coefficients in the γ band of O2 at 628 nm using intracavity laser-absorption spectroscopy (ICLAS) , 1985 .

[17]  V. Mironenko,et al.  Strong dependence of multimode laser generation spectrum on spatial localization of gain and losses , 1982 .

[18]  A. Savitzky,et al.  Smoothing and Differentiation of Data by Simplified Least Squares Procedures. , 1964 .

[19]  F. Stoeckel,et al.  Intracavity laser spectroscopy with vibronic solid-state lasers. I. Spectrotemporal transient behavior of a Ti:sapphire laser , 1994 .

[20]  J. O'Brien,et al.  Intensities and Self-Broadening Coefficients of Weak Water Vapor Lines in the 720-nm Region Determined by Intracavity Laser Absorption Spectroscopy , 1994 .

[21]  J. O'Brien,et al.  Intracavity laser spectroscopy of RF plasmas of methane and benzene used in depositing diamondlike carbon films , 1994 .