Showing papers by "Brian J. Orr published in 2007"
TL;DR: In this article, the authors used numerical simulations to predict the frequency chirp, optical bandwidth, and spectral purity of the signal output pulse as it evolves, including effects that are not readily observed directly.
Abstract: Complicated spectrotemporal processes are associated with the generation of signal and idler output pulses on a nanosecond timescale in an injection-seeded optical parametric oscillator (OPO). The mechanisms of such spectrotemporal dynamics are revealed by numerical simulation, including innovative modeling of instantaneous-frequency profiles and frequency chirp. These simulations are in satisfactory agreement with optical-heterodyne measurements of output from a nanosecond-pulsed OPO system that is based on periodically poled KTiOPO4, pumped at 532 nm by a Nd:YAG laser and injection-seeded at a signal wavelength of ∼842 nm. Frequency chirp in narrowband signal output pulses from such an OPO system has previously been observed to depend on phase mismatch between the pump, signal, and idler waves, and also on the pump-pulse energy. Our simulations accurately predict this behavior and yield realistic estimates of the frequency chirp, optical bandwidth, and spectral purity of the signal output pulse as it evolves, including effects that are not readily observed directly. This approach provides insight into instrumental conditions that facilitate continuously tunable, single-longitudinal-mode operation of such a pulsed OPO system, with optical bandwidth as close as possible to the Fourier-transform limit.
19 citations
TL;DR: A detailed master-equation model is constructed to provide a satisfactory phenomenological fit to the IR-UV DR kinetic data, thereby offering mechanistic insight.
Abstract: Time-resolved infrared-ultraviolet double resonance (IR−UV DR) spectroscopy provides a distinctive way to examine collision-induced state-to-state energy transfer between rotational J-levels in vibrational manifolds of small polyatomic molecules, such as acetylene (C2H2) in its electronic ground state X We consider the 4νCH rovibrational manifold of C2H2 at ∼12 700 cm-1, where the principal source of IR-brightness is the (ν1 + 3ν3) or (1 0 3 0 0)0 vibrational combination level In this highly congested manifold, anharmonic, l-resonance, and Coriolis couplings affect the J-levels of interest, implicating them in a complicated variety of intramolecular dynamics Previous papers of this series have reported several seemingly anomalous J-resolved phenomena induced by collisions in C2H2 gas at room temperature with pressures and IR−UV pump−probe delay intervals corresponding to remarkably high Lennard-Jones collisional efficiencies 𝒫: odd-ΔJ rotational energy transfer (10-3 < 𝒫 < 01), in addition to regula
6 citations
06 May 2007
TL;DR: A cavity ringdown spectrometer, based on a rapidly swept optical cavity and multiple- wavelength coherent radiation, detects several gas-phase molecules simultaneously as mentioned in this paper, which comprises a compact, high-performance instrument for efficient spectroscopic sensing of gases.
Abstract: A cavity ringdown spectrometer, based on a rapidly swept optical cavity and multiple- wavelength coherent radiation, detects several gas-phase molecules simultaneously. This comprises a compact, high-performance instrument for efficient spectroscopic sensing of gases.
2 citations
06 May 2007
TL;DR: In this paper, a novel form of continuous-wave laser spectroscopy entails cavity-ringdown detection of stimulated Raman gain, with co-propagating pump and Stokes beams to minimise Doppler broadening.
Abstract: A novel form of continuous-wave laser spectroscopy entails cavity-ringdown detection of stimulated Raman gain, with co-propagating pump and Stokes beams to minimise Doppler broadening. Molecular rovibrational Raman spectra of methane gas are recorded.
1 citations
26 Aug 2007
TL;DR: In this paper, a high-performance continuous-wave cavity ringdown spectrometer based on either a rapidly swept cavity or a widely tunable swept-frequency laser was developed as a compact versatile instrument for real-time efficient spectroscopic sensing of multiple species.
Abstract: A high-performance continuous-wave cavity ringdown spectrometer, based on either a rapidly swept cavity or a widely tunable swept-frequency laser, has been developed as a compact versatile instrument for real-time efficient spectroscopic sensing of multiple species, innovations, performance of the system, and several applications
26 Aug 2007
TL;DR: In this article, nonlinear optical processes were used to generate narrowband light from an optical parametric oscillator, yielding significantly improved frequency stability compared with dye lasers where the chirp arises principally from population inversion.
Abstract: We use nonlinear optical processes to generate narrowband light from an optical parametric oscillator, yielding significantly improved frequency stability compared with dye lasers where the chirp arises principally from population inversion. We measure chirp using optical heterodyne detection and minimise it by phase matching, producing a near Fourier-transform limited bandwidth.
17 Jun 2007
TL;DR: In this article, the authors simulate spectro-temporal processes in a nanosecond injection-seeded optical parametric oscillator and accurately predict the experimental behavior for the frequency chirp, optical bandwidth, and spectral purity.
Abstract: We simulate spectro-temporal processes in a nanosecond injection-seeded optical parametric oscillator. Our simulations accurately predict the experimental behavior for the frequency chirp, optical bandwidth, and spectral purity, including effects that are not readily observed directly.