Gianemilio Salvetti

A new type of corona‐discharge photoionization source for gas lasers

We present results of an experimental study aimed at characterizing a new type of corona‐discharge photon source, which is particularly suitable to be used as preionizer in transversely excited gas lasers operating at high pulse repetition frequencies. Results of comparative tests carried out in CO2 laser gas mixtures between this photoionization source and a conventional bare spark source are also reported, showing the superiority of the proposed scheme.

Optimization of corona‐discharge photoionization sources for CO2 lasers

The results of an experimental study of ultraviolet photoionization produced by a corona discharge in CO2 laser gases are reported. The influence of corona discharge physical and electrical parameters on the produced photoelectron density is investigated so that an optimized design of these types of photoionization sources can be achieved.

Spatial and spectral response of a Fabry–Perot interferometer illuminated by a Gaussian beam

A generalized study has been done of the transmission characteristics of a Fabry-Perot interferometer (FPI) illuminated by a Gaussian light beam impinging on it at normal and non-normal incidence. The theoretical approach is based on a plane-wave, angular-spectrum representation of both the incident Gaussian beam and the transmitted beam. Expressions are obtained for the FPI instrumental function and for the spatial distribution of the transmitted beam. Numerical results are presented for the FPI maximum transmission, effective finesse, and spectral displacement of the interference maximum.

Extended gas lifetime operation of a miniature transversely excited atmosphere CO2 laser doped with tripropylamine

Long life (≳106 shots), sealed operation of a repetitively pulsed (4 pps), compact (5‐cm3 active volume), transversely excited atmosphere (TEA) CO2 laser has been achieved using an efficient corona‐type preionization and traces of tripropylamine (TPA) as gas additive. The use of TPA has enabled extended operation with a maximum output peak power of about 350 kW.

Comparison of Tm-sensitized Ho:Yag and Ho:YLF crystals for a laser-pumped 2 μm CW oscillator

Abstract We report on a comparison of YAG and YLF crystals for Tm,Ho based CW laser systems operating at 2 μm. As pump source we have used both a Ti:Al 2 O 3 laser and an arry of diode lasers in order to quantitatively assess the relevance of the pump beam spatial features on the 2 μm laser performance. The results are compared with the predictions of a computer simulation using a rate equation model.

Reliable single-mode operation and fine frequency tuning of a Nd-glass low-gain oscillator

Abstract We present a simple, easily tunable cavity configuration which, by means of two low-loss frequency selectors, is capable of forcing low-gain oscillators to reliably operate in single mode. Its application for tunable (up to 20 nm), 100% single-mode operation of a Q -switched, low gain ( G =2), Nd-phosphate glass laser is discussed.

Longitudinal-mode selectivity and perturbation sensitivity of multimirror laser cavities

Some relevant features of a particular type of multimirror laser cavity, i.e., those cavities terminating in highfinesse reflective multipass interferometers, are theoretically investigated with the aim of highlighting the dependence of the level of spectral control achievable with these cavities on their geometrical and optical characteristics. It is shown that cavities equipped with suitably designed reflective multipass interferometers are not only capable of forcing a laser operation on a single longitudinal mode but can act at the same time as effective emission frequency stabilizers because of their inherently low sensitivity to any perturbation affecting the cavity optical length. This feature is particularly attractive for intrapulse and pulse-to-pulse stabilization of high power pulsed lasers. Criteria are given also for the design of optimized cavities that could simultaneously provide narrow linewidth laser emission and minimize the effects of perturbations.

Control of intrapulse frequency chirping in long-pulse CO(2) lasers employing perturbation-insensitive optical cavities.

We present the results of intrapulse frequency chirping measurements that were carried out on a TEA CO(2) laser equipped with various conventional and unconventional frequency-selective optical cavities. We experimentally demonstrate that there is a close relationship between the causes and the extent of intrapulse frequency chirping on the one hand and the type of optical configuration that is used for controlling the laser mode behavior on the other. In particular, it is shown that intrapulse chirping of the emitted frequency can be significantly reduced by employing laser cavities terminating in high-finesse reflective multipass interferometers for single-mode selection. In fact, this type of cavity can be designed in such a way to minimize the effects on the emitted frequency of perturbations affecting the cavity optical length.

Simple, compact, high‐repetition rate XeCl laser

Operation of a compact, corona‐preionized, XeCl excimer laser producing average output power in excess of 1 W at pulse repetition frequencies of up to 750 Hz is reported. This device is simple in construction and utilizes all commercially available components.

Wind velocity, water vapor, and temperature measurements from space using 2-μm Tm:Ho;YAG laser

In meteorological and climatological fields, the scientific community will increasingly need global measurements of key atmospheric parameters with high spatial resolution (horizontal as well as vertical): the spaceborne lidars are the most suitable instruments for those missions. While backscatter lidar (ATLID, currently studied as ESA) is presently first candidate for space deployment, the next generation of lidars will be DIAL and Doppler wind lidars, presenting a higher level of complexity, mainly due to the large power and complex signal processing required. The present considered wind lidars are based on CO2 lasers, whose space compliance still needs confirmation, while alexandrite lasers are considered for water vapor and temperature measurements, but they need flashlamp pumping which poses a lot of several thermal constraints and lifetime problems: on the other side, the recent developments achieved in solid-state technology allow to envisage diode pumping as most promising possibility for both previous applications.