Virtual Journal of Laser

We report on an investigation into a common problem in microbiology laboratories, which is associated with the difficulty of distinguishing/recognising different strains of the genus Staphylococcus. We demonstrate the potential of Raman spectroscopy as a rapid techniques allowing for the identification of different isolates for the detection of biofilm-positive and biofilm-negative Staphylococcus epidermidis strains. For this, the recorded spectra were interpreted using the approach of principal component analysis (PCA). (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Laser characteristics of a novel mixed laser crystal Nd:Lu0.15Y0.85VO4 was investigated. It is attractive for Q-switching with high repetition rate and short pulse width due to its suitable stimulated emission cross-section and short upper level lifetime. Continuous wave (CW) output power of 8.18 W was obtained at the pump power of 18.9 W, corresponding to the optical conversion efficiency of 43.3% and the slope efficiency of 47%. In the passive Q-switching operation, the minimum pulse width attained was 7.8 ns, with the pulse repetition frequency of 23.2 kHz, with the single pulse energy and peak power estimated to be 94.8 [mu]J and 12.2 kW, respectively. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We present for the first time a Nd:YAG laser emitting at 1064 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1064 nm intracavity pumped at 946 nm. Intracavity sum-frequency mixing at 946 and 1064 nm was then realized in a LBO crystal to reach the cyan range. We obtained a continuous-wave output power of 485 mW at 501 nm with a pump laser diode emitting 25.4 W at 809 nm. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The method allowing to detect in real time the laser radiation reflected from metal in course of its processing by powerful fiber ytterbium lasers is proposed. It is shown that there is a correspondence between the behavior of a reflected back signal and the oscillatory processes in a liquid bath of the fused met al. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Here we examined the effect of human normal breast (NB) and breast cancer (BC) tissues in vitro after treatment with glycerol in conjunction with ultrasound (surgeonperformed, SP) by OCT for functional imaging to monitor. 60% glycerol (G) and SP was simultaneously applied for 5 min. Depth- and time-resolved profiles for OCT signal enhancement were presented. The results show that OCT imaging depth of breast tissues after treatment with 60% G in combined with SP more obviously improved than that after application of glycerol alone. The permeability coefficient of 60% glycerol in 60% G/NB, 60% G/BC, 60% G/SP/NB, and 60% G/SP/BC were (0.91±0.02)×10-5 cm/s, (3.22±0.09)×10-5 cm/s, (1.63±0.04)×10-5 cm/s, and (7.98±0.19)×10-5 cm/s, respectively. The permeability coefficient of glycerol in 60% G/SP/NB was 1.84-fold than that in 60% G/NB, but there was 2.54-fold on permeability coefficient comparing 60% G/SP/BC with that in 60% G/BC. The results from this study indicated that the permeability coefficient of glycerol not only in normal breast tissues, but also in breast cancer tissues after treatment with ultrasound is larger than that in tissues without ultrasound.

We demonstrate pulsewidth tunable Q-switched erbium fiber lasers using in-line high extinction ratio (>30 dB) abrupt-tapered fiber Mach-Zehnder block filter and tunable Fabry-Perot filter in laser cavity. The pulsewidth can be tuning over 78 ns - 23 ms. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Lasers from Ho:YAG ceramic were reported in this paper. The Ho:YAG ceramic slab was end-pumped by a Tm:YLF laser whose central wavelength was 1.91 [mu]m. At room temperature, with doping concentrations of 1 at.% Ho:YAG ceramic slab, continuous wave output power of 1.2 W at 2.09 [mu]m was obtained under the absorbed pump power of 5 W, corresponding to a slope efficiency of 42.6% and a conversion efficiency of 24%. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We demonstrate a low-repetition-rate all-fiber all-normal-dispersion Yb-doped mode-locked fiber laser. Stable mode-locking is achieved by nonlinear polarization rotation and its spectral-filtering effect. Nanosecond pulses with steep edges spectrum at repetition rate 217.4 kHz are achieved. Our preliminary experiment shows that it is a promising seed for all-fiber amplifier system. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We report a diode-pumped Nd:YAG laser emitting at 899 nm based on the 4F3/2 - 4I9/2 transition. A power of 1.04 W at 899 nm has been achieved in continuous-wave operation with a fiber-coupled laser diode emitting 19.2 W at 809 nm. Furthermore, intracavity second-harmonic generation in continuous-wave mode has also been demonstrated with a power of 284 mW at 449.5 nm by using a BiB3O6 (BiBO) nonlinear crystal. The fluctuation of the blue output power was better than 2.8%. The beam quality M2 value is 1.3. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Nonlinear optical interactions based on [chi](2) and [chi](3) effects were investigated in the tetragonal, non-centrosymmetric melilite-type crystal Sr2ZnGe2O7. Among them are Stokes and anti-Stokes lasing comb generation, SHG, THG, SFG, and cascaded [chi](3) [harr] [chi](2) self-frequency conversion, arising from onemicron picosecond pumping. All lasing components were identified and attributed to a single SRS-promoting vibration mode [omega]SRS [ap]778 cm-1. The crystals possess a wide transparency range from [ap]0.25 [mu]m to [ap] 6.2 [mu]m; their refractive indices show a small birefringence (with an isoindex point at 0.4677 [mu]m wavelength) that does not allow phase matching for [chi](2)-based conversion processes. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)