K. V. Dukel'skii

Efficient anti-Stokes generation through phase-matched four-wave mixing in higher-order modes of a microstructure fiber

Phase-matched four-wave mixing in higher-order modes of microstructure fibers allows unprecedentedly high efficiencies of anti-Stokes frequency conversion to be achieved for subnanojoule femtosecond laser pulses. 70-fs pulses of 790-nm radiation were used to generate an anti-Stokes component at 520-530 nm in a higher-order mode of a microstructure fiber with a 4.8-microm core. The maximum ratio of the anti-Stokes signal energy to the energy of the pump component in the output spectrum is estimated as 1.7.

Cross-phase-modulation-controlled spectral transformations of ultrashort pulses in photonic-crystal fibres

Cross-phase modulation provides an efficient means to control spectral transformations of femtosecond laser pulses in photonic-crystal fibres with a specially designed dispersion profile. Femtosecond pulses of fundamental radiation of a Cr?:?forsterite laser are shown to induce an asymmetric spectral broadening of the anti-Stokes signal generated in a photonic-crystal fibre by the pulses of second-harmonic radiation of the same laser. Cross-phase-modulation-induced phase shifts control the efficiency of anti-Stokes generation in a photonic-crystal fibre, suggesting a method of switching the anti-Stokes signal on and off by varying the intensity of the control laser pulse.

How the pitch of a holey optical fiber affects its lightguide properties

This paper discusses how scaling (increasing) the transverse dimensions of a holey optical quartz fiber affects its lightguide properties. It is established that a limiting pitch exists, and that, when this is exceeded, the lightguide properties of a holey optical fiber are weakened.

Low-dispersion optical fiber highly transparent in the UV spectral range

The National Ignition Facility performs fusion experiments using ultraviolet (351 nm) light. High-bandwidth, low-attenuation optical fibers are required to transport subnanosecond, UV laser diagnostic signals from the target chamber area to recording instruments located in adjacent rooms, with some fiber runs approximately 65 m in length. Special optical fibers are developed and fabricated to perform this task, since no existing commercially available fibers possess all of the required characteristics. These large-core (435 µm) fibers have optical dispersions less than 0.9 psec/m and attenuations less than 150 dB/km at 351 nm.

Three types of microstructured large core fibers: Development and investigation

Large core microstructured fibers are intensively investigated because of their application in the area of laser physics and high-power light transfer to decrease the non-linear processes. In holey fibers with solid glass core single-mode regime becomes the endless one over the spectra and the most suitable manner of core increasing is scaling of the fiber dimensions without any change in the fiber structure. But the investigations [1] of the endlessly single-mode large-core fibers have shown the main problem: increase of the core diameter leads to the shift of the modal leaking boundary to the long-wavelength region. In [2] the authors managed to increase the core (comprised of 7 or 19 central elements) diameter up to 35 and 50µm and to obtain the laser generation, but no evidence about the modal consistence has been presented.

Spectronanoscopy of photonic wires and supercontinuum generation by parametrically coupled Raman sidebands.

Within a narrow spectral region around the wavelength of zero-group-velocity dispersion of a nonlinear-optical waveguide, phase-matched four-wave mixing couples the Stokes Raman sideband of a pump field to its anti-Stokes counterpart. This wave coupling suggests a sensitive probe for linear and nonlinear-optical parameters of the waveguide, enabling the detection of nanoscopic size variations of microchannel waveguides in photonic-crystal fibers, and facilitates the generation of broadband supercontinuum radiation.

Forming nanosize Y 2 O 3 :Eu 3+ coatings on glass surfaces, using solutions containing polyvinylpyrrolidone

This article describes the formation of homogeneous nanosize (50–250 nm thick) Y2O3:Eu3+ coatings on glass surfaces, using water and water–alcohol solutions of yttrium and europium nitrates. The characteristic bands of macroscopic Y2O3:Eu3+ powders are observed in the absorption spectra of the resulting coatings. The results of electron-microscopic analysis show that mutually orthogonal nanosize rods that lie in the plane of the coating can be formed in the process of the thermal evolution of homogeneous Y2O3:Eu3+ coatings.

Microstructured lightguides with a quartz core for obtaining a spectral supercontinuum in the femtosecond range

Quartz fiber lightguides with a core (diameter 1-5 µm) surrounded by a hexagonal system of holes and having high numerical aperture have been developed and implemented for the spectral conversion of ultrashort laser pulses into broad-band radiation (a supercontinuum). It is shown that the spectral range from 400 to 1000 nm can be covered when the radiation of a Ti-sapphire laser is used.

Novel bend-resistant design of single-mode microstructured fibers

We designed and manufactured two types of a silica-based microstructured fiber (also referred to as holey fiber) having a large core size: first type which contains a circular core and correspondingly possesses the circular symmetry in the waveguide cladding, and second one representing non-typical triangular structure with periodically placed large and small holes. Our primary aim of investigation remained the same as at the previous stages [1], i.e. to create favourable conditions for the strong attenuation of the higher-order mode. The main technological method we applied was variation of air content in the area surrounding the core, especially in the first air-hole ring.

Large aperture Nd-glass laser amplifiers

Rod amplifiers (RA) and disk amplifiers (DA) with apertures of Øw (20–140)mm and (200×200)mm and (300×300)mm are presented accordingly. Platinum-free Nd-glass with different concentration of neodymium ions is used.