Proceedings of Topical Meeting on Optoinformatics (pdf-format, 1.21 ...

66 OPTOINFORMATICS’05
propagation in fused silica fiber [1] . Pulses initially separated by time delay, but since they
have different central wavelengths the lower frequency pulse overtakes higher frequency
one and interaction takes place. The spectrum <strong>of</strong> resulting sequence is shown on Fig. 2.
The width <strong>of</strong> each spectral peak that corresponds single pulse in output sequence is about
20 nm that is similar to standard coarse WDM systems channel width. But such sequences
are interested not only as optical source for WDM systems, they can be used alone as
method <strong>of</strong> encode and transmit data packages in practically one optical signal (Fig. 3) not
splitting it by several channels. However since the spectrum <strong>of</strong> complete sequence is very
wide the application area is limited to short distances.
Fig. 3. Example <strong>of</strong> bit package encoding by “cutting <strong>of</strong>f” specific spectral components from quasidiscrete
spectrum <strong>of</strong> output sequence (a) and corresponding spectrum (b)
The number <strong>of</strong> pulses in the output sequence can easily be managed just by changing
the time distance between input pulses. Further analysis <strong>of</strong> two pulses interaction in
nonlinear media shows that not only pulses collision and passing one through another is
important, but ultrabroadening <strong>of</strong> their spectrums and interaction <strong>of</strong> separate spectral
components <strong>of</strong> each pulses plays a significant role. If both pulses spectrums are in normal
group dispersion range their front contains lower-frequency components, then the tail –
higher frequencies. Thus it is possible to use not only pulses with different mean
wavelengths, but similar pulses also. The principle <strong>of</strong> sequence generation remains the
same – the generation takes place because <strong>of</strong> the interaction <strong>of</strong> the pulse fragments with
different spectral composition.
Thus, the work shows that interaction <strong>of</strong> two intensive few-cycle laser pulses in
nonlinear media may result in generation <strong>of</strong> sequence <strong>of</strong> ultrashort signals. The sequence
has a quasi-discrete spectrum that allows effectively usage <strong>of</strong> such sequence for
information encoding.
The work is supported by Grant N 05-02-16556 <strong>of</strong> the Russian Foundation for Basic
Research.
1. Shpolyanskiy Yu.A., Belov D.L., Bakhtin M.A., Kozlov S.A. Analytic study <strong>of</strong>
continuum spectra pulse dynamics in optical waveguides // Appl. Phys. B: Lasers and
Optics. 2003. V.77. N.2 3, P. 349 355.