I. V. Tomov

Large bandwidth pulse compression with diffraction gratings

Abstract The theory of a grating-pair compressor is developed, taking account of the cubic term into the expansion of the phase shift with the frequency, as well as the finite aperture of the input beam. Large bandwidth pulses with linear chirp will emerge after the compressor with satelite pulses.

Subnanosecond pulse duration measurements by noncollinear second harmonic generation

Abstract A new scheme for measuring the pulse duration using noncollinear second harmonic generation is proposed. Correlation functions of single subnanosecond pulses may be recorded with short crystals by introducing a proper delay. Pulsewidth in the 100 ps-1 ns range was measured using this technique.

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.

Novel absorber for passive mode-locking of Rhodamine 6G dye laser

Abstract A novel saturable absorber for mode-locking of Rhodamine 6G dye laser is presented. Pulses as short as 60 fs have been obtained at 617 nm from a CW passively mode-locked ring dye laser in CPM regime. The new dye is remarkable for its stability in comparison with the widely used mode-locker DODCI.

Effects of excited-state absorption and stimulated emission in UV dyes on the shortening of laser pulses interacting with saturable absorbers

Saturation properties of the dyes in the presence of excited-state absorption and amplified spontaneous emission in the dye are studied theoretically. In the analysis the above two effects are included separately and it is shown that they are deleterious to the pulse-shortening capabilities of the dyes. It is also shown that in the conventional single-pass shortening of laser pulses with saturable dyes large pulse shortening ratios (⩾20) may be expected if the dye saturation is combined with a properly delayed dye generation.

Growth of Raman-Stokes waves in focused pump beams

A theoretical analysis of the process of forward and backward Raman-Stokes pulse growth in a focused pump beam is presented. The position of the peak of the Stokes pulse duration build-up is determined as a function of the focusing lens. Numerical integration of the propagation equations shows strong modulation in the backward Stokes wave and high efficiency

Self-heating effects in electro-optic light modulators

The performance of an electro-optic light modulator under high average laser power is studied theoretically and experimentally. Absorption of laser radiation produces a thermal gradient in the electro-optic crystal which degrades the performance of the modulator. Measurements on modulators using KDP and KD*P crystals support the analytical results.

Generation of tunable UV radiation in the range 216–234 nm

Abstract Nd:glass laser frequency is converted to the UV. The second harmonic of the infrared light excites a tunable dye laser. The three frequencies of the fundamental, SH and dye laser are summed in calcite, resulting in a frequency tunable signal in the range 216–234 nm with a power of about 15 kW. The fifth harmonic of the Nd:glass laser is detected.

Two-wavelength operation of a femtosecond ring dye laser

We report on two-wavelength operation of a CPM ring dye laser employing Rhodamine 6G as gain medium and a new styryl dye as saturable absorber. Two trains of femtosecond pulses at different wavelengths are simultaneously generated under proper alignment of the laser. The secondary pulse train is attributed to the laser action of the absorber dye. Auto- and cross-correlation measurements are performed to determine the temporal characteristics of the laser in the double mode-locking regime.

A simple technique for real time pulsewidth measurements of single ultrashort laser pulses

A simple technique is described employing noncollinear second harmonic generation, for real time measurement of the pulse duration of individual pulses in the 1 ps to 1 ns range. The pulsewidth is derived from the recorded two points of the second-order autocorrelation function. The system may be used as a permanent on-line monitor of the pulsewidth.