Laserati

A diode-side-pumped actively Q-switched Nd:YAG/SrWO4 intracavity Raman laser has been demonstrated, in which a Nd:YAG module is used as the fundamental laser source and a SrWO4 crystal is used as the Raman active medium to generate first-Stokes laser at 1180 nm. A convexplane cavity is employed to make the laser in a stable and efficient work under high pump power. At a LD pump power of 164 W and a pulse repetition frequency of 20 kHz, an average output power of 10.5 W at 1180 nm is obtained. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

A high efficient, continuous wave (CW), cryogenic operation of c-cut Tm(5 at.%),Ho(0.3 at.%):YAlO3 (YAP) laser was reported in this paper. In the temperature of 77 K, the Tm,Ho:YAP crystal was double end-pumped by double 7.25-W fiber-coupled laser diodes (LDs) at the center wavelength of 793.3 nm. A mirror of high reflector (HR) with a 300-mm radius of curvature acted as a resonator mirror, the output wavelength of laser was 2044 nm; the flat output coupler (OC) was 30% transmission at 2.044 [mu]m, a CW output power of 2.28 W was acquired, corresponding to an optical-optical conversion efficiency of 15.7% and a slope efficiency of 19.3%. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Cisplatin-resistance is a major obstacle for the successful therapy to ovarian cancer, and exploring novel approach to deactivate cisplatin-resistant ovarian cells will improve the clinical outcomes. Our present study showed that there was no dark cytotoxicity of MPPa in the COC1/DDP cells at the dose of 0.25 - 4 [mu] M, and LED-activated MPPa resulted in drug doseand light-dependent cytotoxicity. Apoptotic rate 6 h after LEDactivated MPPa (2 [mu] M) increased to 16.71% under the light energy of 1 J/cm2. Confocal laser scanning microscopy showed that MPPa mainly localized in the intracellular membrane system, namely the endoplasmic reticulum, Golgi apparatus, lysosomes and mitochondria in the COC1/DDP cells. Mitochondrial membrane potential ([Delta][Psi]m) was collapsed when COC1/DDP cells were exposed to 2 [mu] M MPPa for 20 h and then 1 J/cm2 irradiation of LED source.

In this paper, the crystal growth and characterization of Nd:Gd3Alx Ga5-x O12 (x = 0.94) (Nd:GGAG) was reported. The X-ray powder diffraction studies confirm that the Nd:Gd3Alx Ga5-x O12 crystal is isostructural with Gd3Ga5O12 (GGG) with unit cell parameter of 1.2319 nm. The absorption and emission spectra of the Nd:GGAG crystal at room temperature have been studied. With a laser-diode (LD) as the pump source, continuous-wave (CW) laser performance at 1.06 [mu] m of Nd:GAGG crystal was demonstrated for the first time to our knowledge. The maximum power of 2.44 W from Nd:GAGG laser was obtained with the optical conversion efficiency 28.5%, and slope efficiency of 28.8%. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

By using GaAs as both a saturable absorber and an output coupler, a laser-diode pumped passively Q-switched Nd:LuVO4 laser has been realized for the first time to our knowledge. The maximum laser output power of 1.91 W has been obtained at the incident pump power of 12.7 W, corresponding to an optical conversion efficiency of 15%. At this incident pump power, the minimum the pulse width of 3.8 ns has also been obtained at the pulse repetition rate of 952 kHz with peak power of 482 W. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Laser performance of Yb:YAG ceramics and singlecrystals doped with different Yb concentrations was investigated using two-pass pumping miniature laser configuration. Highly efficient laser performance was obtained for both Yb:YAG ceramics and single-crystals. For the low doping concentration, the laser performance of ceramics is lower than those of their singlecrystal counterpart. However, better laser performance was observed for heavy-doped Yb:YAG ceramic than single-crystal (CYb = 20 at.%). The maximum optical-to-optical efficiency decreases with Yb doping concentration for both Yb:YAG ceramics and crystals. However, the decrease of maximum opticalto-optical efficiency is faster for Yb:YAG crystals than that for Yb:YAG ceramics with Yb doping concentration. The effects of Yb concentration and the transmission of the output couplers on the laser performance and output laser wavelength of Yb:YAG ceramics and crystals were addressed by taking account into the intracavity laser intensity and reabsorption. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The propagation of a few-cycle laser pulse in a linear gas medium with resonant properties is investigated by the analytical solution of the linear wave equation obtained beyond the approximation of slowly varying envelope and any dispersion approximations. The dispersion effects, absorption processes and the arising of the residual polarization in the medium are studied. In the case of ultrashort laser pulse duration the medium polarization response is found to demonstrate new peculiarities that play a crucial role in the evolution of the spatio-temporal laser pulse profile. The problem of suppression the dispersion broadening of the pulse during the propagation is discussed. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The combined experimental use of laser-induced autofluorescence of cellular metabolites and methodological fundamentals of systems biology will provide access to biological thermal stress analysis on a sub cellular level. A test setup incorporating a pulsed nitrogen laser was realized with which autofluorescence of the coenzyme NADH could be measured in living 3T3 cells. The cells were subjected to different temperature stress at repetitive time intervals.When subjected to a simple mathematical analysis, the NADH concentration change measured through autofluorescence in biological cells exhibited approximate concentration-equivalent balance curves. These results add up to the fundamental know-how about the dosimetry of thermally therapeutic methods. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The polarization properties of one-atom maser pumped by the coherent field via Raman transitions are studied theoretically. The three-level [Lambda] -type atoms with degenerate Rydberg levels Eb < Ea < Ec enter the micromaser cavity being excited to the lower level Eb. The coherent microwave field drives the transition b [rarr] c, while the maser transition a [rarr] c is coupled to the cavity quantum field. The dependence of the maser field parameters, such as the mean photon number and the variance, as well as of the correlation functions of the atoms, emerging from the cavity, versus the angle [psi] between the polarizations of the maser and driving fields are investigated. The case of transitions Jb = 3/2 [rarr] Jc = 3/2 and Ja = 5/2 [rarr] Jc = 3/2 in the rubidium atoms, which are exploited in micromaser experiments (see, e.g., the review [1]), is analyzed numerically. The possibility of monitoring the state of the maser field by means of driving field polarization is discussed. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The study of biological systems in their real environmental conditions is crucial to decipher the true image of structures and processes underlying their functionality. In this regard, development of non-invasive optical techniques that do not require labelling, such as the investigation of tissue endogenous fluorescence, is particularly important and, as reflected in the increasing number of contributions published recently on this subject, was recognized by many leading groups. Multi-spectral and lifetime detection of fluorescence provides an effective experimental tool to discriminate between multiple naturally-occurring fluorophores in living tissues. At the same time, however, data analysis allowing us to understand the spectral, temporal and spatial information gathered, describing individual molecules involved in the autofluorescence of intact biological systems, represents a tough scientific challenge that has not yet been fully resolved. In this review, we discuss the latest advances in technologies that record and assess spectrally-resolved fluorescence lifetime data as well as their biological and clinical applications.