Soliton-based ultrafast multi-wavelength nonlinear switching in dual-core photonic crystal fibre

Abstract

Systematic experimental study of ultrafast multi-wavelength all-optical switching performance in a dual-core photonic crystal fibre is presented. The focus is on nonlinearly induced switching between the two output ports at non-excitation wavelengths, which are generated during nonlinear propagation of femtosecond pulses in the anomalous dispersion region of a dual-core photonic crystal fibre made of multicomponent glass. Spatial and spectral characteristics of the fibre output radiation were measured separately for both fibre cores under various polarization and intensity conditions upon selective, individual excitation of each fibre core. Polarization-controlled nonlinear switching performance at multiple non-excitation wavelengths was demonstrated in the long-wavelength optical communication bands and beyond. Depending on the input pulse polarization, narrowband switching operation at 1560 nm and 1730 nm takes place with double core extinction ratio contrasts of 9 dB and 14.5 dB, respectively. Moreover, our approach allows switching with simultaneous wavelength shift from 1650 to 1775 nm with extinction ratio contrast larger than 18 dB. In addition, non-reciprocal behaviour of the soliton fission process under different fibre core excitations was observed and its effect on the multi-wavelength nonlinear switching performance was explained, taking into account the slight dual-core structure asymmetry. The obtained results represent ultrafast all-optical switching with an extended dimension of wavelength shift, controllable with both the input radiation intensity and the polarization by simple propagation along a 14 mm long fibre.

Nonlinear performance of asymmetric coupler based on dual-core photonic crystal fiber: Towards sub-nanojoule solitonic ultrafast all-optical switching

“…However, in the real asymmetric structure, energies approaching 1 nJ are required to fulfill the nonlinear asymmetry balancing condition (5) in order to obtain true switching performance. These energies correspond to higher soliton numbers than in our previous works [18,19], which is drawback due to the stronger effect of the soliton fission process. Despite that, recent results represent important step towards solitonic high-contrast broadband switching based on dual-core optical fiber with high application potential.…”

“…4 (top), the excited core output expresses lower spectral intensities and narrower bandwidths under fast core excitation in comparison to the slow one. It is typical asymmetric coupler behavior causing transfer of larger energy amount into the non-excited core under fast core excitation [18] as can be also seen from the graphs in Fig. 4 (bottom).…”

“…The utilized special DC PCF possessed a square microstructure design and was made of soft silicate glass with linear and nonlinear refraction indices similar to standard silica. The fiber had a slight dual-core asymmetry, which altered the switching character depending on the choice of the excited core but its impact on the switching mechanism was negligible [18]. The best switching performance has been achieved with 1650 nm 100 fs excitation pulses using 14 mm long piece of the fiber.…”

Nonlinear ultrafast switching based on soliton self-trapping in dual-core photonic crystal fibre

“…Following a one decade of systematic experimental work devoted to the nonlinear dual-core (DC) propagation, in this paper, we present a new approach promising the practical realization of a broadband highly-efficient soliton based NLDC. Our research group demonstrated for the first time the high-contrast switching possibility at non-excitation wavelengths [9][10][11] and developed an extended numerical apparatus giving comparable results with our experimental investigations [12,13]. Using the same numerical tool, now we suggest a novel and realizable switching concept based on the controllable self-trapping of higher-order solitons in the two fibre cores of a HN DC PCF.…”