ABSTRACT
We report the first demonstration of efficient, octave spanning soliton self-frequency shift. In order to achieve this we used a photonic crystal fiber with reduced OH absorption and widely spaced zero-dispersion wavelengths. To our knowledge, this is the largest reported frequency span for a tunable, fiber-based source. In addition, we observe the generation of light above 2 µm directly from a Ti:Sapphire laser in the form of Cerenkov emission by the soliton when the red-shift saturates at the edge of the anomalous dispersion region.
ABSTRACT
An octave spanning spectrum is generated in an As2S3 taper via 77 pJ pulses from an ultrafast fiber laser. Using a previously developed tapering method, we construct a 1.3 µm taper that has a zero-dispersion wavelength around 1.4 µm. The low two-photon absorption of sulfide-based chalcogenide fiber allows for higher input powers than previous efforts in selenium-based chalcogenide tapered fibers. This higher power handling capability combined with input pulse chirp compensation allows an octave spanning spectrum to be generated directly from the taper using the unamplified laser output.
ABSTRACT
The soliton self-frequency shift in As(2)S(3) is investigated theoretically. Differences in the shapes of the Raman spectra in silica and As(2)S(3) are predicted to lead to variations of less than 25% in the frequency shift rate of a fundamental soliton. Detailed simulation of the propagation of a low peak power pulse in a chalcogenide ridge waveguide shows the concepts of Raman soliton behaviour in silica to be transferrable to As(2)S(3). Thus we predict the effectiveness of the soliton self-frequency shift in contributing to wide bandwidth generation in low-power supercontinua at mid-infrared wavelengths in this highly nonlinear chalcogenide, as well as other nonlinear processing applications such as digital quantization for optical analogue to digital conversion.
