Microjoule level femtosecond optical pulses with double-cladding fiber-based nonlinear chirped-pulse amplification

An all-fiber high-energy nonlinear chirped-pulse amplification system with two-stage double-cladding fiber amplifiers is presented in this paper. It generates pulses with the energy up to 10 μJ at 20 kHz repetition rate and total accumulated nonlinear phase shift as large as 12.8π. The pulses can be compressed to 137 fs with the compensation of mismatched third-order dispersion by self-phase modulation in the fiber amplifiers.     

Passively Q-switched GdVO<Subscript>4</Subscript>/Nd:GdVO<Subscript>4</Subscript> laser with Cr<Superscript>4+</Superscript>:YAG saturable absorber under direct 879 nm diode pumping to the emitting level

A passively Q-switched 1.06 μm laser with Cr⁴⁺:YAG saturable absorber by direct 879 nm diode pumping grown-together composite GdVO₄/Nd:GdVO₄ crystal to the emitting level was demonstrated in this paper. The characteristics of pulsed laser were investigated by using two kinds of Cr⁴⁺:YAG crystal with the initial transmissivity of 80 and 90%, respectively. When the T ₀ = 90% Cr⁴⁺:YAG was used, an average output power of 1.59 W was achieved at an incident pump power of 10 W. The pulse width and repetition rate were 64.5 ns and 170 kHz, respectively. The thermal lens effect of laser crystal was analyzed.     

LD side-pumped Nd:GGG CW laser operating at 1110 and 1105 nm dual wavelengths and 1110 nm single wavelength

A diode-side-pumped continuous-wave Nd:GGG laser operating at dual-wavelength (1110 and 1105 nm) and single wavelength of 1110 nm is demonstrated for the first time. The maximum output power of the 1110 and 1105 nm dual-wavelength operation is 13.2 W. By adjusting the orientation of an insertion mirror, the relative intensities of the two wavelengths can be changed. Thus single wavelength operation at 1110 nm is obtained, and the output power is 9.6 W.     

Vladimir Sergeevich Anashin

On the occasion of the 60th birthday of Professor Vladimir Sergeevich Anashin, we present a review of his significant scientific research and related activities.     

Some Quantum Gate Operators for Continuum Variables in <Emphasis Type="Italic">q</Emphasis>-Deformed Coordinate Representation

By virtue of deformation quantization methods we introduce the q-deformed coordinate representation. A new set of completeness and orthogonality relations composed of the ket and bra which are not mutually Hermitian conjugates are derived. Further, using the eigenket and eigenbra for q-deformed coordinate some important quantum gate operators for continuum variables are realized and their properties are discussed.     

Modeling Fraunhofer diffractive characteristics for modulation transfer function analysis of tilted ring metallic mesh

In order to analyze the Fraunhofer diffractive characteristics and modulation transfer function (MTF) of a tilted ring metallic mesh, an optical intensity distribution model of Fraunhofer diffraction is built using Huygens–Fresnel diffraction theory and the diffraction integral is carried out directly in the tilted mesh plane. The diffraction characteristics of the tilted ring metallic mesh are in good agreement with experimental results, which proves the correctness of the model established. MTF of an optical system with metallic mesh is calculated based on the model established and Fourier transform. Analysis shows that the degradation of MTF caused by diffraction of a ring mesh is much less than that of a square mesh whether they are vertical or tilted to the optical axis. Therefore, ring mesh can provide higher imaging quality than square mesh when they are used as high-pass filters in optical windows. A tilted array diffraction modulating factor is abstracted and believed useful in the analysis of diffractive characteristics of tilted square mesh and ring mesh, and it can be extended to Fraunhofer diffractive characteristics analysis of other tilted diffraction arrays.     

Generation of radially polarized mode using an active cylindrically symmetric birefringence fiber

A class of active fiber is presented as gain mediums of fiber lasers, where a silica layer with spoke-like air slits is introduced between the active core and cladding to obtain birefringence. With an appropriate choice of the design parameters, the fiber can support only the HE₁₁ and TM₀₁ modes. Furthermore, the numerical results show that, corresponding to the optimal rare earth doping profile, the fiber lasers can output a pure TM₀₁ mode with about 79% slope efficiency without using other mode-selective elements.     

Spontaneous quantum Hall states in chirally stacked few-layer graphene systems

Chirally stacked N-layer graphene systems with N≥2 exhibit a variety of distinct broken symmetry states in which charge density contributions from different spins and valleys are spontaneously transferred between layers. We explain how these states are distinguished by their charge, spin, and valley Hall conductivities, by their orbital magnetizations, and by their edge state properties. We argue that valley Hall states have [N/2] edge channels per spin valley.     

Cavity phase matching via an optical parametric oscillator consisting of a dielectric nonlinear crystal sheet

We experimentally demonstrate cavity phase matching for the first time using a sheet optical parametric oscillator which is made of an x-cut KTiOPO(4) crystal sheet. This microcavity presents 220 kW peak power capability for near-frequency-degenerate parametric outputs with up to 23.8% slope efficiency. It also features unique spectral characteristics such as single-longitudinal-mode and narrow linewidth. These attractive properties predict broad applications of such a mini-device, such as terahertz generation, photonic integration, spectroscopy, and quantum information, etc.