Ya. V. Kravchenko

Efficient solid state dye lasers based on polymer-filled microporous glass

This paper reports on the laser emission properties of Pyrromethene 580, Pyrromethene 597, Pyrromethene 650 and Rhodamine 11B in the novel matrix polymer-filled microporous glass (PFMPG). This host material combines the advantages of an organic environment for the dye with the superior thermooptical and mechanical properties of an inorganic glass. Laser efficiency was measured as a function of pump flux for different dye concentrations, resonator feedback, and locations on the sample. Service life, defined as the number of pulses for the output to drop to the 70% point, was recorded at 5 Hz for the higher dye concentrations. The highest efficiencies were observed for Pyrromethene 597 (is congruent to 70%), which had a service life of is congruent to 60,000 shots at 25 MW/cm2 and is congruent to 45,000 shots at 50 MW/cm2. The longest service life was measured for Rhodamine 11B (is congruent to 110,000 pulses at 25 MW/cm2), but this dye had somewhat lower efficiency (is congruent to 50 - 55%). Thermal lensing measurements were made for dye-doped PFMPG and MPMMA, and showed that the lensing is much lower in the hybrid matrix. The agreement with the theoretical modeling is very good.

New high-efficiency pyrromethene-580-doped modified PMMA solid state dye laser

Laser-related properties of pyrromethene-580 doped modified polymethyl methacrylate, including conversion efficiency, operational lifetime, laser induced damage resistance of the polymer matrix and photodestruction of the impregnated dye, were studied under short-pulse and long-pulse laser pumping. High efficiency and operational lifetime have been achieved in the short-pulse mode. Effect of a laser resonator feedback on both the conversion efficiency and lifetime was revealed and studied in the long-pulse operation mode.

Beam-quality measurements on solid state dye lasers using nonconfocal unstable resonators

This paper reports on a systematic study ofthe beam quality ofsolid-state dye lasers for different resonator designs. The resonators investigated include: multimode stable, hard-edge unstable, and unstable with a graded-reflectivity mirror (GRM) output coupler. The purpose ofthe work was to investigate the conditions under which good beam quality can be achieved, and to examine the possible trade-off between beam quality and energy extraction efficiency. Beam quality was quantified through conventional M2 measurements. A hard-edge unstable resonator of magnification ?2.5 produced a beam ofM2 ?11 - 12 at a PRF of 2Hz and a pump flux of 5 MW/cm2. The value increased to ? 18 — 19 at a pump flux of2O MW/cm2. This can be compared with an M2 of ? 140 - 150 with the multimode stable resonator. Preliminary measurements with the GRM resulted in M2 values of ? 5 to 6 at 5 MW/cm2.

Ultrashort-pulse generation in solid state dye lasers

Generation of ultrashort pulses (picosecond range duration) in pyrromethene-580 (PM-580) and xanthene 11B dyes doped modified PMMA polymer lasers is reported. Active polymer elements were pumped by second harmonic radiation of the 50 picosecond Nd:YAG laser. A single-pulse and train-pulse laser generation was observed at different conditions (variable optical resonator length and pump energy) with a pulsewidth ranging from 140 ps to 30 ps. The train-pulse generation is attributed to mode-locking of a laser resonator. The lifetime (tau) e, of an excited quantum state of a laser transition of the PM- 580 dye molecules has been estimated ((tau) e equals 200 divided by 250 ps) from the pulse-train duration.

Measurement of nonlinear optical coefficients by the z-scan technique: Correctness of the technique and investigation of a new compound-lutetium diphthalocyanine complex

Correctness of z-scan measurements of nonlinear refractive indices for optical media is considered. It is shown that accuracy of these measurements is greatly affected by the thickness of the nonlinear medium layer (as compared with the diffraction length of the laser beam). Nonlinear refractive indices of nitrobenzene are measured at different laser pulse durations (7 ns and 350 ps); the nonlinearity mechanism is discussed. It is shown that at the pulse duration 350 ps the orientation mechanism of nonlinearity is less effective than at the pulse duration 7 ns due to its time lag. Nonlinear refractive indices are measured for the solution of a new synthesized compound-hexadecabutyl-substituted lutetium diphthalocyanine.