No abstract

No abstract

Ultrasensitive detection of methane, isotopic carbon dioxide, carbon monoxide, formaldehyde, acetylene, and ethylene is performed in the spectral range 2.5-5 μm using intracavity spectroscopy in broadband optical parametric oscillators (OPOs). The OPOs were operated near degeneracy and synchronously pumped either by a mode-locked erbium (1560 nm) or thulium (2050 nm) fiber laser. A large instantaneous bandwidth of up to 800 cm −1 allows for simultaneous detection of several gases. We observe an effective path-length enhancement due to coherent interaction inside the OPO cavity and achieve part-per-billion sensitivity levels. The measured spectral shapes are in good agreement with a model that takes into account group delay dispersion across the broad OPO frequency band.

No abstract

We report 550 mJ pulses with 14 ns FWHM duration at 1 Hz repetition rate from a Q-switched cryogenic Ho:YLF oscillator pumped with 100 W in 35 ms by a Tm:fiber laser. The laser has a confocal unstable resonator with a graded-reflectance output coupler, resulting in a beam quality of M(2) = 1.5. Pulse energies of 416 and 343 mJ were obtained at 10 and 20 Hz repetition rate, respectively.