Yu. N. Kondrat'ev

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.

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.

Holey lightguides with a quartz core for nonlinear-optical conversion of laser-emission pulses

Holey lightguides based on quartz glass with a solid core 1-5 µm in diameter, surrounded by a hexagonal system of openings with a number of cycles from one to four, have been developed for converting ultrashort laser pulses into a spectral supercontinuum. It has been shown that the wavelength range from 400 to 1300 nm can be overlapped when the radiation of a Ti-sapphire laser is used.

Hollow-core photonic-crystal lightguide for nonlinear spectroscopy of gaseous media

Photonic-crystal lightguides based on quartz glass with a hollow core 17-40 µm in diameter have been developed and implemented. The dependence of the shape of the transmission spectrum on the core diameter and the step of the structure of the polycapillary cladding is investigated. It is noted that there is a substantial reduction of the optical losses by comparison with a counterpart lightguide having continuous cladding.

Low-dispersion optical fiber for the UV region: Method of monitoring the strength

This paper discusses the mechanical characteristics of a quartz fiber with low temporal dispersion (less than 1 ps/m) for operation in the UV region. Sections of fiber 590 µm in diameter were subjected to rewinding with a relative elongation of 0.5 to 1.5%. The Weibull statistic is found for the distribution of defects of a definite size over the length of a fiber. A method is proposed for screening an optical fiber with respect to mechanical strength by rewinding under a double load.

Implementation of a photonic crystal fiber lightguide and generation of broad-band laser radiation in it

Structures with one and two courses of apertures around a central lightguide core whose diameter varies from 1 to 4 mm have been implemented. The radiation losses were about 1 dB/ m. When the lightguide is excited with the radiation of a Ti-sapphire laser having a pulse width of 30 fs and an energy around 1 nJ, efficient lasing of continuous radiation is obtained in the spectral range from 400 to 900 nm.