Spatial-temporal dynamics of the terahertz field generated by femtosecond filament

We present the study on spatial distribution of the maximum of terahertz field amplitude in time domain when generated by a femtosecond filament. It is shown that as a result of the propagation of the terahertz field forms a spherical wave front, on the edge of which the maximum of amplitude has a temporary delay in contrary to its central part

COHERENCE TIME CALCULATION OF FEMTOSECOND SPECTRAL SUPERCONTINUUM IN QUARTZ OPTICAL FIBER

It is shown that in the case of femtosecond spectral supercontinuum generation in quartz fiber in the areas of normal, abnormal and zero group velocity dispersion, with an increase of the central wavelength of the femtosecond laser pulse at the input, the coherence radiation time with ultra-wide spectrum is significantly reduced. However, in the region of zero group dispersion of quartz fiber there is a "leap" of coherence time. For example, for the initial pulse duration of 40 fs at 800 nm at spectral supercontinuum generation in quartz fiber, the coherence time is 22 fs. With the increase of wavelength, the coherence time is reduced to 4 fs at a wavelength of 1180 nm. In the area of zero group dispersion, the coherence time is increased dramatically to 20 fs, after which it is reduced, reaching a minimum of 4 fs at a wavelength of 1560 nm

Blue Lake, Mount Gambier, South Australia, 1880, 1 /

Title devised by cataloguer from item and reference sources.; Inscription: "Blue Lake, Mount Gambier"--In pencil below image.; Part of: Country scenes and stock and station views of South Australia, 1867-1886.; Condition: Yellowing.; Also available online at: http://nla.gov.au/nla.pic-vn6299555-s9

Stability of solutions of linear difference equations with periodic coefficients

This paper represents the last technical contribution of Professor Patrick Parks before his untimely death in February 1995. The remaining authors of the paper, which was subsequently completed, wish to dedicate the article to Patrick. A frequency criterion for the stability of solutions of linear difference equations with periodic coefficients is established. The stability criterion is based on a consideration of the behaviour of a frequency hodograph with respect to the origin of coordinates in the complex plane. The formulation of this criterion does not depend on the order of the difference equation