P. Minguzzi

High-power diffraction-limited Nd:YVO/sub 4/ continuous-wave lasers at 1.34 /spl mu/m

We describe the development of Nd:YVO/sub 4/ lasers with continuous-wave emission at 1.342 /spl mu/m; they contain either one or two crystals which are longitudinally pumped by fiber-coupled diode laser arrays. With a single crystal, the output power is 7.3 W, while with the twin crystal configuration the power reaches 12 W. The best slope efficiency is 40% and the output beam divergence is about two times the diffraction limit. The influence of the Nd concentration, of the pump spot-size, and of the resonator configuration have been experimentally studied. Data on the thermally induced lens are also reported and discussed.

Optoacoustic laser Stark spectroscopy in the ν2 band of 14NH3

Abstract Laser Stark spectroscopy of the R (5, K ) transitions in the ν 2 band of ammonia was carried out using coincidences with the 9-μm band CO 2 laser lines. We observed 22 Doppler-free resonances by using an optoacoustic detector and a Lamb-dip stabilized CO 2 laser. A simultaneous analysis of sa, aa , and ss lines yields zero-field transition frequencies with an absolute accuracy of 1 ∼ 2 MHz.

Sub-Doppler optoacoustic spectroscopy

Abstract We report the observation of saturation Lamb-dips in the optoacoustic spectrum of CH 3 OH and CO 2 excited by CO 2 laser. An intermodulation technique is used to get Doppler-free resolution of the lines. Because of the small sample size and the high sensitivity intermodulated optoacoustic spectroscopy compares favorably with other Doppler-free methods.

Accurate measurements of transition frequencies and isotope shifts of laser-trapped francium

An interferometric method is used to improve the accuracy of the 7S-7P transition frequencies of three francium isotopes by 1 order of magnitude. The deduced isotope shifts for 209-211Fr confirm the ISOLDE data. The frequency of the D2 transition of 212Fr--the accepted reference for all Fr isotope shifts--is revised, and a significant difference with the ISOLDE value is found. Our results will be a benchmark for the accuracy of the theory of Fr energy levels, a necessary step to investigate fundamental symmetries.

Design of an optoacoustic cell for laser-Stark spectroscopy

We report on the development of an optoacoustic cell that is suitable for high-resolution laser-Stark spectroscopy. It is a small volume non-resonant device that has been operated with strong electric fields, up to 36 kV/cm. A Doppler-free Stark spectrum of NH3, obtained with a CO2 laser, is given as an example of its performances.

A diode-laser-pumped tunable Ho: YLF laser in the 2 µm region

We report the cw laser emission of Ho: YLF in an astigmatically compensated resonator under pumping by a laser diode array. We measured the laser efficiency at different operating temperatures of the crystal and the non-saturated gain coefficient at the peak wavelength of laser emission. The laser tunability extends from 2.040 µm to 2.075 µm.

CH3OH and CH381Br self-broadening measurements with a millimeter-wave Stark interferometer

Abstract The collision-broadening coefficient for a rotational transition of methanol at 76.5 GHz has been measured by a novel apparatus. A hyperfine component of methyl bromide at 76.15 GHz has also been studied. The measured values (HWHM) are 132.8 (2.3) kHz/Pa for CH 3 OH and 136.3 (1.8) kHz/Pa for CH 3 81 Br.

Evidence for Stark induced frequency shift in a CH3F fir laser

Abstract We report the first direct measurement of the frequency shift induced by the application of an electric field to an optically pumped CH 3 F far infrared laser. These shifts are obtained only if the laser resonator is slightly detuned, so that the electric field enhances the cavity pulling effects. The maximum Stark coefficient we observed is about 2 kHz/(Volt/cm), fairly sufficient to allow FM modulation or fast laser frequency stabilization.

ACOUSTIC DETECTION IN MILLIMETER WAVE SPECTROSCOPY - PRESSURE BROADENING OF CH3CN

The pressure broadening of the different K components of the J=3–4 rotational line of CH3CN have been measured. A novel experimental apparatus employing a very small cell with an acoustic detector is described and a comparison with theoretically estimated linewidths is discussed.

Operation of High-Intensity Spectral Lamps in a Strong Magnetic Field

A detailed experimental study of the operation of alkali spectral lamps in the presence of a magnetic field has been performed. A new type of lamp is described, featuring high radiance together with simplicity and low price. Moreover, we show that the combined action of hyperfine coupling and self-reversal conditions can cause large deformations in the Zeeman pattern of alkali atoms. The effect is thoroughly studied and a theoretical interpretation is given, in good agreement with the experimental results.