Dispersion measurement of engineered antiresonant hollow-core fibers with spectral interferometry

Abstract

Group velocity dispersion (GVD) plays a significant role in ultra-short pulse propagation in a fiber. Advent of photonic crystal fibers made it possible to tune the fiber dispersion properties and fabricate the fibers with one or two zero dispersion wavelengths (ZDW). This work describes the successful dispersion measurement of fundamental mode in the novel antiresonant hollow core fiber (ARHCF) [1, 2], showing strong GVD variation over hundreds of fs2/cm due to strand resonance in both anomalous and normal dispersion regimes close to the resonance wavelength at ∼900 nm. This abrupt change in dispersion profile favors non-adiabatic soliton dynamics facilitating supercontinuum generation [3]. In our experiment, ∼9 cm long ARHCF (inset of Fig. 1a) is placed in one arm of the balanced Mach-Zehnder interferometer and interference pattern comprising dispersion information is recorded on a spectrometer (Fig. 1b). The phase profile is extracted from the measured spectrogram via Fourier transform and a subsequent fit is shown in Fig 1a [4]. Corresponding GVD variation shows a sudden increase by few orders near resonance region (Fig. 1c). GVD peaks in normal dispersion regime when approached from blue side and towards anomalous regime from red side of the strand resonance. In the lossy resonance region, GVD alternates between normal and anomalous dispersion regimes passing through zero dispersion. However, in resonance several modes each having unique GVD get excited and these multiple superimposed fringe pattern results in discontinuity in GVD measurement of fundamental mode.