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Nonlinear Pulse Dynamics in Photonic Nanowires
We investigate theoretically and experimentally the process of supercontinuum generated in sub-wavelength waveguides. We observe experimentally that supercontinuum generated in these photonic nanowires is increasingly blueshifted from the pump wavelength for decreasing minimum core diameters. We also find the spectral features are sensitive to the specific nanowire profile. Numerical simulations using the nonlinear envelope equation show that accurate modeling requires consideration of the nonlinearity and full dispersion along the entire nanowire profile as well as a wavelength dependent loss. Specifically, the blue-shifting is found to result from an increasing loss for wavelengths larger than the core diameter.
Spectrogram and projected spectral evolution in the sub-wavelength region of a tapered microstructured fiber.
M. A. Foster, J. M. Dudley, B. Kibler, Q. Cao, D. Lee, R. Trebino, and A. L. Gaeta, "Nonlinear pulse propagation and supercontinuum generation in photonic nanowires: experiment and simulation," Appl. Phys. B. 81 363-367 (2005). PDF
Supercontinuum Compression to Few-Cycle Durations
By exploiting the broad region of anomalous group-velocity dispersion (GVD) and the large effective nonlinearity of photonic nanowires, we demonstrate soliton-effect self-compression of 70-fs pulses down to 6.8 fs. Under suitable conditions, simulations predict that self-compression down to single-cycle duration is possible.
Retrieved few-optical-cycle pulse self-compressed from the 70-fs input pulse by propagation in the 980-nm core diameter and 2-mm long photonic nanowire pictured above the plot.
M. A. Foster, A. L. Gaeta, Q. Cao, and R. Trebino, "Soliton-effect compression of supercontinuum to few-cycle durations in photonic nanowires," Opt. Express 13, 6848-6855 (2005). PDF
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a.gaeta@cornell.edu