The characterization of new gain-switched Fe:Cr:Zn_1–xMg_xSe laser working at the room temperature and its comparison to Fe:ZnSe laser was performed. The laser oscillation behavior, generation efficiency and output wavelength tuning possibilities were demonstrated. It was shown that the absorption and luminescence spectra of Fe:Cr:ZnMgSe crystal are shifted towards longer wavelengths in comparison with Fe:ZnSe active material. The difference is approximately 300 nm and it corresponds to measured absorption and emission spectra. The maximal Fe:Cr:ZnMgSe laser generated energy and the slope efficiency with respect to the absorbed energy were 200 µJ and 4.5%, respectively. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Multiple Stokes and anti-Stokes χ⁽³⁾-nonlinear generation in the tetragonal crystal of CaYAlO₄ was observed at 300K and ≈9K under picosecond excitation in the visible spectral range. All the recorded Raman induced laser lines were identified and attributed to the SRS-promoting vibration mode of octahedral [AlO₆]^–9 units of the crystal. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

In combination with morphological evaluation tests, we employ Raman spectroscopy to select higher potential reproductive embryos during in vitro fertilization (IVF) based on chemical composition of embryos culture medium. In this study, 57 Raman spectra are acquired from both higher and lower quality embryos culture medium (ECM) from 10 patients which have been preliminarily confirmed by clinical assay. Data are fit by using a linear combination model of least squares method in which 12 basis spectra represent the chemical features of ECM. The final fitting coefficients provide insight into the chemical compositions of culture medium samples and are subsequently used as criterion to evaluate the quality of embryos. The relative fitting coefficients ratios of sodium pyruvate/albumin and phenylalanine/albumin seem act as key roles in the embryo screening, attaining 85.7% accuracy in comparison with clinical pregnancy. The good results demonstrate that Raman spectroscopy therefore is an important candidate for an accurate and noninvasive screening of higher quality embryos, which potentially decrease the time-consuming clinical trials during IVF. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Intra-cavity frequency doubling of continuous-wave (CW) laser emission on the quasi-three level (⁴F_3/2 → ⁴I_9/2) laser transition of Nd³⁺ in Nd:GGG is reported by using a three-mirror folded resonator. The thermal lens experienced by the optically-pumped Nd:GGG laser crystal is measured as a function of the absorbed pump power and compared to that found, in the same conditions, in the case of Nd:YAG. Results are interpreted by using a simple model accounting for the absorbed pump power and the thermo-mechanical properties of each laser crystal. Diode-pumped blue laser operation is achieved, for the first time, at 467.0 and 468.5 nm with output powers of 230 and 450 mW, respectively. Simultaneous laser operation resulting both from frequency-doubling and frequency summing at the three 467.1, 467.7, and 468.1 nm laser wavelengths is also obtained with a total output power of 60 mW. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

In this work it is shown, that laser with injection of reflected radiation can possess the high longitudinal spatial selectivity. Laser figures here both the emitter and the detector of radiation. This attribute, having volumetric character for laser fields, can be considered as a new modality in optical microscopy. Using the experimental possibilities we achieved the spatial resolution at a level of several microns. The optimization of laser sources is to lead to longitudinal spatial resolution at a level of nanometers. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

A compact diode-pumped solid-state Tm:KY(WO₄)₂ laser with cavity length of 1 cm passively Q-switched with a PbS-quantum-dot-based saturable absorber is presented. The laser operates at the wavelength of 1.94 µm and produces pulses with duration of 8 ns and energy of 30 µJ at the repetition rate up to 4.2 kHz. The maximum output power of 120 mW is achieved at incident pump power of 1.15 W. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We presented the rapid diagnostic test for dengue infection based on light spectrum of human blood. The transmission spectra of dengue infected whole blood samples have been recorded in ultra violet to near infrared range (400–800 nm) of about 30 conformed infected patients and compared to normal blood samples. Transmission spectra of dengue infected blood illustrate a strong band from 400–600 nm with prominant peaks at 540 and 580 nm, where is in case of normal blood below 600 nm, total absorption has been observed. These prominent peaks from 400–600 nm are characteristics of cells damage and dangue virus antibodies immunoglobulin G (IgG) and immunoglobulin M (IgM) produced against dengue antigen. The presented diagnostic method is non invasive, cost effective, easy and fast screening technique for dengue infected patients. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Spectroscopic properties and continuous-wave laser performance of a new Yb_0.015:Lu_0.162Gd_0.823VO₄ mixed vanadate crystal are reported. An appreciable discontinuous increase in output power occurs during the σ - to π -polarization switching process in the laser oscillation. A maximum output power of 4.3 W is generated with an optical-to-optical efficiency of 46%, whereas the average slope efficiency is determined to be 73–77%, depending on the output coupling utilized. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The present work gives a brief review of the nonlinear χ⁽²⁾- and χ⁽³⁾-lasing properties of SRS-active natural crystals (minerals) known so far. This compilation complements new results of a detailed investigation of Raman induced χ⁽³⁾-effects in aragonite single crystals (orthorhombic CaCO₃) under single- and dual-wavelength picosecond excitation in the UV, visible and near-IR spectral ranges. The studied effects at room and cryogenic temperatures comprise Stokes and anti-Stokes combs of almost two octaves bandwidth, THG, SFG, as well as cascaded and cross-cascaded χ⁽³⁾ ↔ χ⁽³⁾ interactions. All recorded lasing χ⁽³⁾-components were identified and attributed to three observed SRS-promoting vibration modes ω_{SRS 1} ≈ 1087 cm^–1, ω_{SRS 2} ≈ 152 cm^–1, and ω_{SRS 3} ≈ 205 cm^–1 (at room temperature) of aragonite. Stimulated Raman scattering (SRS) investigations of minerals so far enrich the arsenal of SRS-active crystals, which can be applied to solve fundamental and applied tasks of modern laser physics and nonlinear optics. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

High-order harmonic generation is realized in a semi-infinite gas cell using a commercial, amplified Ti:Sapphire system operating at 5 kHz and delivering 30 fs pulses at 800 nm. A schematic of the experimental setup is shown in Cover Picture. Using an f = 100 cm focusing lens placed ≈97 cm from the pinhole, intensities of ≈1 × 10¹⁴ W/cm² are produced. The pulses are not CEP-stabilized, which is unproblematic because we are investigating the interference of quantum paths of the same half cycle [8]. The target chamber is filled with 75 mbar of argon and terminated by a 100 µm pinhole, causing an abrupt transition to vacuum. As shall be discussed below, this geometry does not favor either the long or the short quantum paths. In the analyzer chamber the generated XUV radiation is dispersed spectrally by a reflective flat-field grating (1000 lines/mm, Hitachi), positioned ≈1035 mm downstream from the pinhole, and impinges upon a micro-channel plate (MCP, Hamamatsu) with a fluorescent back screen. This signal is imaged onto a CCD camera, enabling us to resolve the harmonic radiation both in angle and frequency in the far field, i.e. in the (ω, θ) domain. (Cover picture: S.M. Teichmann, D.R. Austin, et al. pp. 207–211, in this issue) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The review of studies of the high-order harmonic generation of laser radiation in laser-produced plasma describes the developments in this field during last half decade. We show that this approach in frequency conversion of laser radiation towards the extreme ultraviolet range became matured during multiple sets of studies carried out in many laboratories world-wide and demonstrated new opportunities for efficient generation of strong coherent short-wavelength radiation. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We present for the first time, to the best of our knowledge, a 1359 nm continuous-wave (CW) Nd:Lu₂O₃ laser based on the ⁴F_5/2 – ⁴F_13/2 transition. The use of a pump module with 16 passes through the crystal allowed the realization of a Nd:Lu₂O₃ thin-disk laser with 3.52 W of CW output power. The slope efficiency with respect to the incident pump power was 21.4%, and the fluctuation of the output power was better than 3.55% in the given 2 hour. The beam quality factor M² is 1.14 and 1.18 for tangential direction and sagittal direction, respectively. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Thanks to its high emission cross section around 1 µm, Yb:CaNb₂O₆ is a good candidate for laser operation near 1 µm as shown in our figure of merit. We demonstrated, for the first time to our knowledge, laser operation of Yb:CaNb₂O₆ at 1003 nm. More than 2.23 W at 1003 nm and 577 mW at 501.5 nm were produced simultaneously. This visible wave length corresponds to an iodine transition previously studied with argon ionized lasers for metrological applications. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

The ZnWO₄:Tm³⁺ single crystal has been grown by Czochralski method and the concentration of Tm³⁺ is 0.2 at.%. End-wing -pumping ZnWO₄:Tm³⁺ crystal by 795 nm LD, we obtain a novel ∼ 1.9 μ m eye-safe laser. At different temperatures, the laser output versus pump power is measured. At 283 K, the highest output power is up to 240 mW and the slope efficiency is 1.7%. By means of the quasi-three energy level theory, we investigate the optimized crystal length. Results indicate that the slice laser system is more suitable for the end pumping ZnWO₄:Tm³⁺ crystal. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We observe ring structures in high-order harmonics generated in the loose focusing geometry of a semi-infinite gas cell. Phase matching and absorption considerations indicate that the measured signal is restricted to the harmonics generated in the exit plane. We therefore attribute the ring structure to interferences in the single-atom response in the transverse exit plane of the interaction region. Calculations using the stationary phase approximation were used to analyze the contributions of the long and the short trajectories, respectively, and confirm our experimental findings. The simple setup makes quantum path interference measurements feasible without the need for special filtering mechanisms. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We propose a new scheme of attosecond pulse generation by starting from a narrow-band transform-limited high-power solid-state laser and phase lock the fundamental and its first four cascaded harmonics generated by the second-order nonlinear optical processes. The relative phase among the optical fields of the harmonics can be maintained a constant at least for thousands of nanosecond pulses. The worst-case relative phase fluctuation is 0.04π rad. It is shown that sub-single-cycle (∼0.37 cycle) sub-femtosecond (360 attosecond) pulses with carrier-envelope phase (CEP) control can be generated in this manner. The peak intensity of each pulse exceeds 10¹⁴ W/cm² when it is focused to a spot size of 20 µm. We also demonstrate synthesis of square and saw-tooth waveforms. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We have realized supercontinuum source based on the silica-cladding fiber with the germanate-glass-core pumped by Q-switched Er-doped fiber laser. The long-wavelength edge of the spectrum obtained is located at 2.7 µm. To our best knowledge it is the longest wavelength for the silica based fiber. Average output power as high as 0.49 W was measured. Intensity variation in the range of 1.6 – 2.7 µm was much less than one decade. The fibers with different lengths were tested. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We present an all-fiber passively mode-locked Ra-man laser using graphene as a saturable absorber. Different lengths of a highly non-linear fiber presenting normal dispersion at both pump and signal wavelengths are used in the cavity to provide Raman amplification. The cavity is pumped by a continuous wave Raman laser at 1450 nm, and generates short pulses around 1550 nm, which depending on polarization and filtering parameters can be either at the repetition rate of the cavity or at higher harmonics of it. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We report on the generation of multiwavelength passively mode-locked pulses in an erbium-doped fiber laser (EDFL) based on the interaction of graphene and fiber-taper evanescent field. Graphene-polymer nanocomposites in aqueous suspension are trapped by the optical evanescent light and deposited on taper region. The graphene-deposited fibertaper device not only acts as an excellent saturable absorber for mode-locking, but also induces a polarizing effect to form an artificial birefringent filter for multiwavelength selection. By simultaneously exploiting both functions of this device, four-wavelength continuous-wave mode-locking operation of an EDFL is stably initiated with a pulse width of 8.8 ps and a fundamental repetition rate of 8.034 MHz. This is the first time, to our knowledge, the mode-locked EDFL using such a new geometry of graphene-based tapered-fiber saturable absorber has been demonstrated. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

We investigate the interactions between proteins and DNA in solutions of living cells, triggered by UV, 200-fs laser pulses. DNA-protein crosslinking is obtained with two different techniques: conventional chemical or laser-induced. Our results evidence a nonlinear response of the cells to the laser irradiation in the investigated intensity range. The laser induced crosslink efficiency can reach a value approximately twice higher than that obtained with ordinary chemical methods. The experimental results are very well reproduced by a simple phenomenological model based on the interplay between two-photon absorption by DNA bases and cell damage induced by high intensity laser pulse. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

Electrical pulse-mediated enhanced silver nanoparticles delivery is a much better method for intracellular surfaceenhanced Raman spectroscopy (SERS) measurements of suspension cells. Robust and high-quality SERS spectra of living suspension cells were obtained based on an electroporationSERS method, which can overcomes the shortcoming of nonuniform distribution of silver nanoparticles localized in the cell cytoplasm after electroporation and reduces the amount variance of silver nanoparticles delivered into different cells. The electroporation parameters include three 150 V (375 V/cm) electric pulses of 1, 5, and 5 ms durations respectively. Our results indicate that considerable amount of silver nanoparticles can be rapidly delivered into the human promyelocytic leukemia HL60 cells, and the satisfied SERS spectra were obtained while the viability of the treated cells was highly maintained (91.7%). The electroporation-SERS method offers great potential approach in delivering silver nanoparticles into living suspension cells, which is useful for widely biomedical applications including the real-time intracellular SERS analysis of living cells. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)

In counterfactual quantum key distribution (CQKD) information is transferred, in a secure way, between Alice and Bob even when no particle carrying the information is in fact transmitted between them. In this letter we fully implement the scheme for CQKD proposed in [1], demonstrating for the first time that information can be transmitted between two parties without the transmission of a carrier. (© 2012 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)