I V Chaltakov

Shortening of excimer laser pulses with saturable absorbers

Abstract Shortening by a factor of more than five of XeCl laser pulses by a single pass saturable absorber is recorded. The pulse shortening is attributed to the combined action of both nonlinear absorption and stimulated emission from the dye solution.

A widely tunable XeCl excimer laser

Abstract An extension of the tuning range up to 16.2 A of a convenient XeCl, UV preionized, electrodischarge laser is reported. Lasing on four new transitions, B(ν=0)-X(ν=4,5) and B(ν=1)-X(ν=6,7), with energies in the order of 1 υJ was achieved. Additionally a continuous tuning between the transitions B(ν=0)-X(ν=0) and B(ν=1)-X(ν=7) was recorded.

An efficient high pressure XeCl discharge laser with UV pre-ionisation

The results from an improved simple UV pre-ionised XeCl discharge pumped laser are reported. Using an optimised pre-ionisation geometry and simple flat-profile electrodes, stable laser operation was obtained at a buffer gas pressure of 0.7 MPa with a specific energy extraction of 7.2 J l-1 at. 1.2% efficiency. An efficiency of 3.8% with 4.2 J l-1 energy extraction has been obtained at a buffer gas pressure of 0.7 MPa and 15 kV charging voltage.

An efficient and compact discharge-excited XeCl laser

The operational characteristics of a discharge-excited XeCl laser utilising a discrete element pulse-forming network (PFN) are reported. A pulse output energy of 0.6 J, an efficiency of approximately 2% and an energy extraction of 4.5 J litre-1 were recorded at a relatively low charging voltage. With neon buffer gas, pulses of 80 ns (FWHM) were measured.

Transverse discharge pumped triatomic Xe2F excimer laser

Abstract Fluorescence and lasing of the triatomic Xe 2 F molecule was studied in a transverse discharge excited device with UV preionization. Laser emission peaking at 600 nm with a spectral bandwidth of 40 nm was recorded using a Xe-NF 3 -Ne mixture. Both fluoresence and lasing were obtained under conditions typical for the conventional diatomic rare gas halide lasers.

Short-pulse generation from XeCl excimer laser

Single pulses of duration less than 2 ns have been produced by a XeCl excimer laser incorporating intercavity saturable absorber and focusing optics.

Design of a sine-wave constant current source switching power supply for laser applications

The design and performance of a simple resonant tank circuit, sine-wave, constant current source switching power supply are described. On the basis of a simplified circuit model, the main equations describing the operation of the power supply when the load voltage varies with time are evaluated and the general design formulae are presented. A comparison is made between the results given by the exact numerical model of the circuit and the results obtained using the inferred formulae. The circuit diagram of the constructed and investigated 40 kV, 15 mA sine-wave, constant current source switching power supply is given. An efficiency of 92% was measured and the actual parameters agreed within 10% with those calculated beforehand.

Monte Carlo simulation study of the diffusely reflected photons from a semi-infinite turbid media

Monte-Carlo simulations of the light diffusive reflectance from semi-infinite turbid media were performed in order to study the possibility for a stationary diagnostic of biological tissues. Initially the intensity distribution of the diffusively reflected photons as a function of the separation from the light source was calculated for a wide range of absorption and scattering coefficients. The typical maximum in the radial distribution of the intensity was detected. Analyzing those results a relation between the intensity maximum position and the scattering coefficient was observed for all the cases studied. Suggesting that the relationship mentioned could be concludable for an estimation of the scattering coefficient of the tissue an additional study of the angular distribution of the diffusively reflected photons was also made. As a result the applicability of an optical fiber light probe for collection of the photons was discussed. Finally, it was concluded that the steady-state intensity dependence of the diffusively reflected photons on the separation from the light source could be applicable for biologic tissue diagnostics.

Stimulated Raman scattering of XeCl 70 ns laser pulses in silica fibres

For the first time stimulated Raman scattering (SRS) in multimode silica fibres pumped with relatively long XeCl laser pulses (70 ns) has been observed. The spectral and temporal development of SRS has been studied both experimentally and theoretically. Two orders of SRS have been obtained in the 311-317 nm spectral region. The experimental results are in good agreement with computer simulations of SRS in which the effects of self- and cross-phase modulation and group velocity dispersion are negligible. Included in the numerical model are experimentally measured spectra of the Raman gain curve and the pump laser spectra.

Stimulated Raman scattering of long XeCl laser pulses in silica fibers

For the first time, stimulated Raman scattering (SRS) in multimode silica fibers pumped with long XeC1 laser pulses (70 ns) has been observed. The spectral and temporal development of SRS, both experimentally and theoretically, have been studied. Two orders of SRS have been obtained in the 311 divided by 317 nm spectral region. The experimental results are in good agreement with computer simulations of SRS, in which effects of self- and cross-phase modulation and group velocity dispersion are negligible. Experimentally measured spectra of the Raman gain curve and the pump laser spectra are included in the numerical model.