7 research outputs found
Topological dissipative Kerr soliton combs in a valley photonic crystal resonator
Topological phases have become an enabling role in exploiting new
applications of nonlinear optics in recent years. Here we theoretically propose
a valley photonic crystal resonator emulating topologically protected
dissipative Kerr soliton combs. It is shown that topological resonator modes
can be observed in the resonator. Moreover, we also simulate the dynamic
evolution of the topological resonator with the injection of a continuous-wave
pump laser. We find that the topological optical frequency combs evolve from
Turing rolls to chaotic states, and eventually into single soliton states. More
importantly, such dissipative Kerr soliton combs generated in the resonator are
inborn topologically protected, showing robustness against sharp bends and
structural disorders. Our design supporting topologically protected dissipative
Kerr soliton combs could be implemented experimentally in on-chip
nanofabricated photonic devices.Comment: 16 pages, 12 figure
Graphitization of polyacrylonitrile carbon fibers and graphite irradiated by γ rays
To investigate the effect of γ-ray radiation on the microstructure of carbon fibers (CF) and graphite, the carbon fibers and graphite were irradiated by 60 Co source at room temperature. X-ray diffraction results indicate that the interlayer spacing d 002 of CF and graphite decreased after irradiation. The intensity of (002) peak in CF decreased while the peak of the (002) plane in graphite becomes sharper after irradiation. Scanning electron microscopy combined with energy dispersive X-ray spectroscopy determines that γ-ray irradiation slightly improves the carbon content of CF surface layer. Compton scattering effect and heating caused by γ-ray are proposed to be responsible for the graphitization of CF and graphite. Crow