J. C. Hernandez-Garciaa, *, O. Pottieza, and J. M. Estudillo-Ayalab
a Centro de Investigaciones en Optica (CIO), Loma del Bosque 115,
Col. Lomas del Campestre, Leon, Gto. 37150 Mexico
b Division de Ingenierias Campus Irapuato-Salamanca, Universidad de Guanajuato,
Carretera Salamanca-Valle de Santiago Km 3.5+1.8 Km, Comunidad de Palo Blanco, Salamanca, Gto., 36885 Mexico
*e-mail: juancarlos@cio.mx
Received June 22, 2011; in final form, June 30, 2011; published online October 24, 2011
Abstract—We report the experimental study of broadband spectrum generation in a piece of standard fiber
(SMF-28) using as the pump a train of noise-like pulses, or sub-nanosecond packets of sub-ps pulses with ran-
domly varying amplitudes. The pulses are generated by an erbium-doped figure-eight fiber laser, and present a
wide (~50 nm) optical spectrum, which represents a significant advantage to seed the generation of new fre-
quencies. Another advantage of the pulses is their relatively large energy, as they are made up of a large number
of ultrashort pulses. After amplification with an Erbium Doped Fiber Amplifier (EDFA), the pulses were
injected in a 0.75 km length of SMF-28 fiber. We obtained experimentally at the end of the fiber an output signal
spectrum extending from 1530 nm to at least 1750 nm (the upper limit of the spectrum analyzer) for pump
pulses with an average power of 20.4 mW, corresponding to a few kilowatts peak power. The spectral broaden-
ing is due to Raman self-frequency shift (SFS). It is noteworthy that the spectrum of the newly created frequen-
cies was extremely uniform over the range of measurement. Considering that the Raman shift is directly related
to the pump pulse duration, spectral flatness is a direct consequence of the random distribution of amplitudes
and durations of the pulses in the packet. Finally, the results show the capabilities of noise-like pulses from a
fiber laser for applications in supercontinuum generation based on nonlinear phenomena such as Raman SFS.
10.1134/S1054660X1123006X
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