T. Sh. Efendiev

Interaction of interference laser field with an ensemble of particles in liquid

Abstract The dependence of the spatial redistribution of microparticles in a suspension under the action of an interference laser field on the particle parameters and field characteristics is theoretically analyzed. The experimental results illustrating the optical trapping of an ensemble of polymeric balls and other microparticles in liquid by interference fringes of the He–Ne laser radiation ( λ =632.8 nm) are presented. The interferometric trapping of microparticles was observed at a light power as low as ∼2 mW. It was also found that regular crystal-like structures of particles are formed as a result of interaction of the particle ensemble with the gradient light field produced by a softly focused single He–Ne laser beam.

Simultaneous oscillation of several independently tunable spectral lines in a distributed feedback dye laser

Abstract A simple method is proposed which allows obtaining distributed-feedback laser action simultaneously at several spectral lines of any wavelength with independent tuning within the gain profile of the dye.

The effect of an external mirror on the characteristics of an N2 laser-pumped distributed feedback dye laser

Abstract The effect of an external mirror on the DFB dye-laser parameters was investigated experimentally. When a 100% mirror was used, the output energy quadrupled, the divergence decreased to the diffraction limit. Besides the study of the improvement of laser parameters, the temporal behaviour of the amplified spontaneous emission and the DFB dye-laser action were simultaneously investigated.

Generation of tunable picosecond pulses in a simple distributed feedback dye laser under N2-laser pumping

Abstract Simple possibility of single tunable picosecond pulse generation in a conventional inexpensive distributed feedback dye laser (DFDL) is demonstrated. It is shown that when a TEA N 2 -laser is used for pumping no diffraction grating is necessary in the DFDL optical scheme for operation in the picosecond regime. Hence wide-range spectral tuning from 357 to 665 nm was easily achieved. When pumped with a 0.6 ns 40 kW pulse of the TEA N 2 -laser the DFDL generated pulses as short as 7 ps with time-bandwidth product better than 0.6 and peak power ∾ 10 kW. At a repetition rate of 50 pps the shot-to-shot energy stability of a single picosecond pulse was ±18% at ±7% stability of the TEA N 2 -laser.

Recording volume holograms in dye-activated aqueous gelatin gel

Holographic characteristics of a thick photosensitive material based on a dye-activated aqueous gelatin gel have been studied. Holograms recorded using second harmonic radiation of YAG:Nd3+ laser with a pulse duration of 17 ns showed a diffraction efficiency of ∼70% and an angular selectivity of ∼20′.

Modulation of Particle Concentrations in the Interference Laser Radiation Field

Spatial redistribution of microparticles in a suspension on exposure to the interference laser field depending on the parameters of the particles and the field characteristics has been analyzed theoretically. Results of experimental investigations are presented that illustrate the capture of an ensemble of polymeric small spheres and also of the lymphocytes of human blood and other microparticles in a liquid in the interference radiation bands of the He–Ne laser.

SPECTRAL-LUMINESCENT AND GENERATION CHARACTERISTICS OF A GEL-LIKE GELATIN DOPED WITH A DYE

We present the results of comparative measurements of spectral–luminescent characteristics of Rhodamine 6G and Rhodamine C in water and water–gelatin solutions. We found that gelatin added to a water solution disaggregates the molecules of the dye. The maxima of the absorption and luminescence spectra of the solution shift then to the longwave region. The quantum yield of luminescence and the efficiency of generation of the solutions investigated are measured. The generation intensity of the gel is shown to depend on its composition and the dye selected. Measurement of spectral–luminescent characteristics of water–gelatin solutions makes it possible to select dyes that would generate most efficiently in gel solutions.

Holographic DFB laser with fan-shaped grating for a spectrofluorimeter

A method for recording fan-shaped transmitting phase holographic gratings that ensure tuning of the wavelength of emission for a DFB (distributed-feedback) dye laser is presented. Traditional optical elements are used in the scheme of grating recording. A change in the degree of grating fanning is reached here without replacement of gratings. The possibility of obtaining frequency-tuned emission by means of the fan-shaped gratings created is demonstrated experimentally.

Distributed feedback dye laser: a simple instrument for measurement of refractive index of laser media

It is shown that distributed feedback (DFB) dye laser may be efficiently employed for measurement of the refractive index of liquid and solid laser materials. Spectral and temperature dependencies of refractive index of dye laser solutions, polymer matrices and micro-porous quartz samples doped with dye are investigated. The change of refractive index of the sample was determined by the wavelength shift of DFB dye laser. A home-made DFB dye lasers with liquid and solid active media tunable in a wide spectral range (400 nm - 760 nm) were used in the experiments.

Volume hologram multiplexing in dye-doped jelly-like gelatin

A thick-layer selfdeveloping photosensitive medium - dye-doped jelly-like gelatin was earlier proposed and investigated by us [1,2]. It provides optical recording of the stationary volume phase gratings with high values of diffraction efficiency and angular selectivity. For a wide range of scientific and technical applications including holographic data storage, holographic optical elements, photonic crystals etc. multiplexed volume holograms are required. In this work an angular multiplexing of the volume phase Bragg gratings in dye-doped jelly-like gelatin is reported.