All-optical ultrafast switches based on thin film coated-tilted fiber Bragg grating

All-optical switching could play a significant role in future high-speed telecommunication networks. Switches based on tilted fiber Bragg gratings (TFBG), coupling the forward propagation core mode to hundreds of discrete backward propagation cladding modes provide a novel platform for light-matter interaction by modulation of material permittivity via the evanescent field of cladding modes which in turn modulate the cladding resonances shifts in wavelength and/or amplitude. In this thesis, in-situ, real time detection of the percolation of Ag films coated on the surface of fibers is achieved through measurements of TFBG transmission spectra by gradually etching the metal films to thicknesses between 15-25 nm. Secondly, all-optical photo-thermal based bistability and self-pulsing, i.e., repetition rate up to 269 Hz and pulse width of 1.4 ms was achieved by using a multi-layered graphene-coated TFBG pumped by single Watt-level CW laser light in the fiber core. Thirdly, all-optical synchronous modulation of a probe CW signal propagating in a gold-coated TFBG immersed in water was achieved by excitation of a plasmonic hybrid cladding guide mode. A 1 MHz, 25 ps long pump signal with average power of 50 mW at one wavelength modulated the low power CW probe at another wavelength by 4.5%, with a widened duration of 56 ps due to hot carrier generation in the gold coating. Finally, broadband antireflection of cladding guided light was demonstrated at the same thicknesses where percolation occurred, which leads to further potential applications in fiber-based nonlinear light-matter interactions.