Cross-correlation frequency resolved optical gating analysis of broadband continuum generation in photonic crystal fiber: simulations and experiments

Abstract

Numerical simulations are used to study the temporal and spectral characteristics of broadband supercontinua generated in photonic crystal fiber. In particular, the simulations are used to follow the evolution with propagation distance of the temporal intensity, the spectrum, and the cross-correlation frequency resolved optical gating (XFROG) trace. The simulations allow several important physical processes responsible for supercontinuum generation to be identified and, moreover, illustrate how the XFROG trace provides an intuitive means of interpreting correlated temporal and spectral features of the supercontinuum. Good qualitative agreement with preliminary XFROG measurements is observed.

Time-Spectral Visualization of Fundamental Ultrafast Nonlinear-Optical Interactions in Photonic Fibers

“…in the vicinity of the 2ZD point is negative, whereas it is positive near the first zerodispersion point, typical for the regular fibers and previous generations of PCFs Dudley et al, 2002;Dudley et al, 2006). Theoretical predictions (Skryabin & Yulin, 2005;Biancalana et al, 2004) and previous experiments (Harbold et al, 2002;Skryabin et al, 2003;Genty et al, 2004) suggested unusual soliton dynamics in the vicinity of the 2ZD point.…”

“…Indeed, recent supercontinuum generation experiments in these SF6 PCFs indicate that a multioctave continuum can be generated efficiently in only millimeters of fiber using 100 fs pulses at telecom wavelengths and nanojoule energies (Omenetto et al, 2006). Previous measurements of supercontinua in time-frequency suffered from low signal-to-noise ratio and thus could not be directly compared to numerical results (Dudley et al, 2002). Nevertheless, low-noise broadband measurements with X-FROG are possible and may look almost indistinguishable from the numerically generated spectrograms.…”

“…In addition, technical difficulties arise if complex or broadband pulses are being measured, such as phasematching bandwidth requirements for SHG FROG or spectral phase interferometry for direct electric field reconstruction (SPIDER), or sensitivity in polarization-gating FROG and others. This is why the very first timeresolved images of supercontinuum generated in silica PCFs were obtained using crosscorrelation methods-the sum-frequency generation (SFG) X-FROG (Dudley et al, 2002) and cross-correlation sonogram measurements (Hori et al, 2004). In a typical cross-correlation approach the signal pulse is gated with a different reference pulse, usually a replica of the input pump pulse split off before the nonlinear medium under study and appropriately delayed.…”

Similariton-Based Spectral Interferometry for Signal Analysis on Femtosecond Time Scale

“…A spectral detection of the SFG-signal will give also information on the chirp of similariton, modifying the cross-correlation technique to the cross-correlation frequency-resolved optical gating (XFROG) [49,50]. Our additional modification is the use of a dispersively chirped reference pulse, which provides a spectrally compressed SFG-signal in a wider spectral range, and thus, more efficient measurement [22,44].…”

Dynamics of Raman soliton during supercontinuum generation near the zero-dispersion wavelength of optical fibers

“…In particular, the ideal periodic evolution of a higher-order soliton is perturbed by third-and higher-order dispersions (HOD) to the extent that it breaks into its fundamental components, a phenomenon known as soliton fission [9]. These fundamental solitons experience IPRS-induced red shifts, and this shift is largest for the shortest soliton with the highest peak power, also called the Raman soliton [4,10]. During the fission process, HOD terms lead to transfer of energy from the soliton to a narrowband resonant DW, also called non-solitonic radiation [8,9,11].…”