Dispersion-engineered Photonic Crystal Waveguides Research Articles

Higher order dispersions effect on high-order soliton interactions

The object of the research is deleting the interaction of the higher order soliton interaction by introducing the third and fourth order dispersions inside an optical fiber. The results are obtained by the simulation of the nonlinear Schrödinger equation, which models the propagation of solitons in the optical fiber using the method of Fast Fourier Transform. The interaction of two higher order solitons due to the attraction of their electric field can lead to losing the solitons' properties. Hence, this can prevent the use of solitons in high-bit-rate optical fiber communication systems because it increases the bit error rate, significantly limiting the potential of the communication system. To resolve this problem, we should diminish the bit rate error by avoiding the interaction of the co-propagative solitons when they are too close. It is well known that, during higher order soliton propagation in the presence of the third order dispersion, the irregular shape of the higher order soliton disappears, and a splitting towards its fundamental constituents occurs after a considerable propagation. As for the fourth order, dispersion gives rise to two dispersive wave sidebands on the red or blue side. Our results reveal that bringing two higher order solitons together in the presence of the fourth order dispersion, a series of interactions between the components generated after their fission is obtained. In the third-order distribution, besides the fourth-order diffusion, the rare form and the supercontinuum generated by the fission of the higher-order solitons disappear, and we get two fundamental solitons propagating in parallel with a temporal shift and some inconsiderable dispersive waves. The most important aspect is that both higher-order dispersions are able to suppress the interactions of higher-order solitons thanks to the time shift induced by the third-order distribution and the intermittent compression caused by the fourth-order scattering. These results can be obtained in practice inside the dispersion-engineered photonic crystal waveguide (PhC-wg), which allows for manipulating the high order dispersion.

Probing molecular absorption under slow-light propagation using a photonic crystal waveguide

High-resolution infrared absorption spectroscopy of acetylene gas is demonstrated in a dispersion-engineered photonic crystal waveguide under slow-light propagation. Experimental enhancement factors of 0.31 and 1.00 are obtained for TE and TM polarization, respectively, for group indices ranging from 1.5 to 6.7. The dependence of molecular absorption on the evanescent electric-field distribution and on the group index under structural slow-light illumination is experimentally demonstrated and confirmed by time-domain simulations.

Blue Self-Frequency Shift of Slow Solitons and Radiation Locking in a Line-Defect Waveguide

We investigate experimentally resonant radiation processes driven by slow solitons in a dispersion-engineered photonic crystal waveguide in a regime virtually free of dissipative nonlinear processes (two-photon absorption and Raman scattering). Strong (30% energy conversion) Cherenkov-like radiation accompanied by the blue self-frequency shift of the soliton is observed close to the zero dispersion point, and is explained in terms of the soliton-radiation locking of the velocity.