Experimental studies of the coherence of microstructure-fiber supercontinuum

Abstract

The phase coherence of supercontinuum generation in microstructure fiber is quantified by performing a Young's type interference experiment between independently generated supercontinua from two separate fiber segments. Analysis of the resulting interferogram yields the wavelength dependence of the magnitude of the mutual degree of coherence, and a comparison of experimental results with numerical simulations suggests that the primary source of coherence degradation is the technical noise-induced fluctuations in the injected peak power.

Limits of coherent supercontinuum generation in normal dispersion fibers

“…The dominating set of nonlinear effects is determined by fiber and pump pulse parameters, and in general a pump pulse soliton number of N ≤ 10 is required to maintain high coherence. In practice, this corresponds to pump pulse durations of < 100 fs, while SC generated with longer pulses tend to show strong pulse-to-pulse fluctuations [18][19][20][21]. Although fibers with longitudinally varying dispersion were numerically investigated to extend the coherent regime to pump pulses with picosecond durations [22], the necessary careful adjustment of the fiber design to specific pump pulse parameters prevented experimental realization.…”

Nonlinear Optics and Solitons in Photonic Crystal Fibres

“…These simulations clearly show that although the spectrum may be very similar for input pulses of different duration, only pulses of ≤ 50 fs duration will yield good coherence over the full spectral bandwidth. The predictions are borne out by experiment [30] and by the evidence of the many successful metrology or stabilization [27,28] schemes using short pulses, and the failure of attempts to use 75 fs laser pulses to the same ends, even by the same research teams [28]. The simulations also point to a direction where good coherence is possible, even with long pulses, namely with very short fibre lengths, where the spectrum appears as a SPM spectrum.…”

Nonlinear optical interactions in silicon waveguides

“…The pulseto-pulse variations of the supercontinuum have been measured in an interferometric setup [27] shown in Figure 10. In the setup, a pulse is temporally overlapped with the next pulse and the optical spectrum is recorded.…”

“…There have been several demonstrations of nonlinear experiments in silicon nitride integrated waveguides and hydex waveguides [14]. Most notably, frequency comb generation [27][28][29][30][31]. However, the nonlinear parameter of such waveguides is relatively small.…”