Diffraction of collinear correlated photon pairs by an ultrasonic wave.

The phenomenon of collinear correlated photon pair diffraction by an ultrasonic wave is investigated for Bragg incidence. A beta-barium borate crystal was used for producing collinear correlated photon pairs via type-I spontaneous parametric down-conversion. It is shown experimentally that the Bragg angle for photon pair diffraction is identical to the one corresponding to single-photon diffraction.

Diffraction of collinear correlated photon pairs by an ultrasonic wave within Raman-Nath and intermediate region.

The phenomenon of collinear correlated photon pairs diffraction by an ultrasonic wave is investigated within Raman-Nath and intermediate region. The numbers of single photons and photon pairs counts in discrete diffraction orders were measured as functions of the Raman-Nath parameter. Similarly, the number of coincidence photon counts in separate diffraction orders was also investigated.

Acousto-optic interaction with the use of cylindrical ultrasonic waves in the laser cavity.

In this paper, acousto-optic interaction between laser light and cylindrical airborne ultrasound in both He-Ne laser and argon-ion laser cavities is considered. The modulation properties of these acousto-optic systems were studied. The schlieren technique has been used to visualize a cylindrical ultrasonic wave generated in the air by radial vibration of a cylindrical piezoelectric shell.

Some recollections on acousto-optics research at the University of Gdańsk in the light of international cooperation and of the history of Spring Schools on Acousto-Optics and Applications.

Some historical features of international cooperation that have been a background for originating the idea to organize since 1980 special international meetings named Spring Schools on Acousto-Optics and Applications and for continuing the events until now are presented. Thanks to the establishment of the Spring Schools, the group of acousto-opticians at the Gdańsk University have had the opportunity to exchange scientific experience and continue mutual cooperation in research with several acousto-optic centers and to publish a number of common papers. A few examples from these achievements and some historical facts illustrating research activity in the field of acousto-optics during past 30 years are recollected.

Acousto-optic interaction of a Gaussian laser beam with an ultrasonic wave of cylindrical symmetry.

We present experimental studies of the interaction between a narrow Gaussian laser beam and a standing cylindrical ultrasonic wave. As a theoretical approach, a Fourier-optics-based successive diffraction model is used. Depending on the ratio of the Gaussian laser beam diameter to the first nodal diameter of the cylindrical ultrasound, light refraction or diffraction is observed.

Light diffraction by two parallel superposed ultrasonic waves of the frequency ratio 1:2.

The paper constitutes a concise study of light diffraction by two superposed ultrasonic waves of the frequency ratio 1:2, beyond the Raman-Nath diffraction regime. Relevant numerical simulations of light intensity distribution within separate diffraction orders are shown based on the Nth order approximation method (NOA). A comparison is given between generalized theoretical predictions (N=7) and simplified formulas of Mertens (N=2) [R.

Tumor suppressor Fhit protein interacts with protoporphyrin IX in vitro and enhances the response of HeLa cells to photodynamic therapy.

Fhit, the product of tumor suppressor fragile histidine triad (FHIT) gene, exhibits antitumor activity of still largely unknown cellular background. However, it is believed that Fhit-Ap(3)A or Fhit-AMP complex might act as a second class messenger in cellular signal transduction pathway involved in cell proliferation and apoptosis. We demonstrate here for the first time that the photosensitizer, protoporphyrin IX (which is a natural precursor of heme) binds to Fhit protein and its mutants in the active site in vitro.

Application of electrophoretic methods for detection of protein-porphyrin complexes.

Simple methods for detection and isolation of protein-porphyrin complexes were elaborated in our laboratory. They are based on the separation of protein-porphyrin complexes in native polyacrylamide gel and measurement of their fluorescence, with the use of two detection systems: the commercially available Gel Doc(TM) 2000 system, and a system specially designed for the purpose of these investigations, concerning protein-porphyrin interactions. The fluorescent complexes can be electro-transferred from the gel onto PVDF membrane, eluted and analyzed in order to identify the protein interacting with porphyrins.

Acousto-optic lens for pulsed lasers.

Theoretical predictions of the acousto-optic interaction under Raman-Nath conditions of ultrasound and laser light with a beam width w comparable to or smaller than the ultrasonic wavelength lambda are experimentally investigated, and good agreement between experiment and prediction is found. The experimental setup consists of a pulsed laser, emitting pulses that are synchronized with the sound frequency by means of a controllable delay time. When w approximately lambda, strong focusing is obtained for most delay times.

Acousto-optic polarizer.

In the paper theoretical bases are presented, as well as their experimental verification, concerning an idea of a new type acousto-optic light ellipticity modulator, based on light diffraction phenomenon by ultrasonic waves, within the so-called intermediate diffraction regime. The experimental data obtained really good match relevant theoretical predictions, and the device examined enables a continuous light ellipticity variation from 0 up to 1, with low diffraction loses and for low electric voltage applied to ultrasonic transducer.

Diffraction of light by two ultrasonic beams of frequency ratio 1:2, beyond the Raman-Nath diffraction regime.

Light diffraction by two ultrasonic waves of frequency ratio 1:2 is examined beyond the Raman-Nath diffraction regime. Measurements were taken of +/- 1 order diffracted light intensities for some Raman-Nath parameter values, as a function of the phase shift between the sound beams. The experimental results obtained are discussed and compared with relevant theoretical predictions.

On the polarization of light diffracted by ultrasound.

If light is diffracted by ultrasound in an isotropic medium with acoustically induced birefringence, the state of polarization is modified in each order of diffraction with respect to the initial state of polarization of the incident light wave. In the present paper, some polarization effects are discussed in the case of normal light incidence. In general a rotation of the main polarization plane occurs, together with a change of the ellipticity.