E. M. Telles

New FIR laser lines from CD3OD optically pumped by a CO2 waveguide laser

In this work we report new FIR laser lines from CD3OD optically pumped by a CO2 waveguide laser. The wide tunability of this laser (290 MHz) makes it possible to pump absorption lines with large frequency offset relative to the CO2 laser line center, which are not possible by using conventional CO2 lasers. As a consequence 19 new laser lines have been discovered, ranging from 38.0 μm to 455.2 μm in wavelength. For all lines, precise frequency offset measurements between the CO2 line center and the center of the absorber CD3OD line were performed using the transferred Lamb-dip technique. We also present direct Doppler-free offset measurements of infrared absorption, obtained within the FIR laser cavity itself, using optoacoustic detection.

New fir laser lines and frequency measurements from optically pumped13CD3OH3

We report the discovery of 57 new fir laser lines from13CD3OH molecule optically pumped by a waveguide CO2 laser of 300 MHz tunability. For all lines, precise frequency offset measurements between the CO2 line center and the center of the absorbing13CD3OH line were performed using the transferred Lamb-Dip technique. We have also measured directly the frequency of seven FIR laser lines by heterodyning with already known laser lines. We present a complete list of all known laser lines (134) and frequency measurements (24) for this molecule.

CD3OD optically pumped by a wave guide CO2 laser: New FIR laser lines and frequency measurements

Abstract We report the discovery of new FIR laser lines from the CD 3 OD molecule optically pumped by a waveguide CO 2 laser. The increased tunability (300 MHz) with respect to a conventional CO 2 laser permits pumping IR CD 3 OD lines of larger offset. As a consequence 19 new laser lines have been discovered and the known FIR laser lines from this important molecule are thus increased to 220. For all observed laser lines, precise offset measurements of the pump lines from the CO 2 laser were performed through the transferred Lamb-Dip technique. The frequency of seven laser lines was also directly measured by heterodyne detection with already known laser lines. An additional new FIR laser line was found to be generated by the CD 3 OH molecule.

Frequency Stabilization of Waveguide CO2 Laser by a Digital Technique

In this work we present a simple technique for laser frequency stabilization, based on Digital signal processing. The technique is used to stabilize a waveguide CO2 laser of wide tunability by using three kinds of reference signals: the CO2 laser ouptut power, an infrared absorption optoacoustic signal and the output power of a Far-Infrared optically pumped molecular laser.

Experimental investigation of13CD3OH infrared transitions by means of optoacoustic spectroscopy

A systematic investigation of13CD3OH infrared transitions around CO2 laser line emissions is performed by means of optoacoustic detection. Using a waveguide CO2 laser of 290 MHz tunability and, in some cases, an acoustooptic modulator to provide an extension of 180 MHz, 108 transitions are observed. Measurements of pump off-set and relative intensity have been performed. The data may be compared with those previously reported of high resolution Fourier Transform spectroscopy.

Photoacoustic spectrometer for ozone detection

A high-resolution external laser photoacoustic spectrometer has been developed. The spectrometer was used to analyze the absorption transitions of the ozone in coincidence with the CO2 laser emission and to evaluate its limit of sensitivity. A CO2 laser and a photoacoustic resonant cell, totally built in project, formed the spectrometer. The CO2 laser operates in 80 CW transitions distributed in the regular bands with power of up to 15W, tuned by a diffraction grating. The cell has frequency resonance of longitudinal mode close to 1600 Hz. The cell is equipped with two small electret microphones and ZnSe windows in Brewster angle. The quality factor of the cell was measured about 30 through the ozone absorption in resonance with the 9P14 line of CO2 laser. The spectrometer sensitivity limit was preliminary evaluated for ozone detection around 100 ppb.

Doppler-free optoacoustic measurements in FIR laser active molecules

Abstract Saturation effects in FIR laser active molecules were observed by using a Doppler-free optoacoustic spectrometer. 13CH30H and CD3OH were firstly used to calibrate the optoacoustic spectrometer. Some new infrared transitions could be observed. By using a waveguide CO2 laser as optical source and CD3OD as the main absorption molecule we were able to observe 35 infrared transitions, several of which not previously reported. As a consequence, some of these transitions were used in an experiment of optical pumping to search for new FIR laser lines. The collisional broadening influence on the linewidth of Doppler-free optoacoustic signals was also observed.

Electric field effects on roto-vibrational transitions of13CD3OH1

We used a Stark-Optoacoustic cell and hybrid waveguide resonators to perform an Infrared and Far Infrared Stark Spectroscopy study on some transitions of13CD3OH. Different behaviours of the transitions in the presence of a d.c. electric field were observed. The Stark splittings of six FIR laser lines ranging from 34 to 136 MHz/kVcm−1 were determined. The analysis of the behaviour of the IR and FIR transitions in the presence of the external electric fields gives important and exclusive information on the levels involved in the transitions.

Homogeneous Linewidth and Saturation Parameter of Infrared Laser Transitions

We investigated the behavior of infrared (IR) absorption laser transitions of methanol isotopes in the presence of an uniform electric field, in order to determine Doppler-free spectroscopic data such as homogeneous linewidth and saturation parameter. For this we combine photoacoustic detection with the high resolution provided by the Nonlinear Hanle Effect (NLHE) on molecular transitions.

Deceleration of a calcium atomic beam by a frequency-doubled diode laser

Deceleration of an atomic beam of calcium was achieved by using the radiation of a frequency double diode laser at 845.2 nm. In order to enhance the violet beam generation the doubling crystal, KNbO3, is placed inside an external build-up cavity. The laser beam at 423 nm, counter- propagating with the atomic beam, is put into resonance with the 1S0 yields 1P1 transition of Ca. To keep the laser in resonance with the atomic transition during the cooling process, the Zeeman technique is used.