Microresonators are ideal systems for probing nonlinear phenomena at low thresholds due to their small mode volumes and high quality (Q) factors. As such, they have found use both for fundamental studies of light-matter interactions as well as for applications in areas ranging from telecommunications to medicine. In particular, semiconductor-based resonators with large Kerr nonlinearities have great potential for high speed, low power all-optical processing. Here we present experiments to characterize the size of the Kerr induced resonance wavelength shifting in a hydrogenated amorphous silicon resonator and demonstrate its potential for ultrafast all-optical modulation and switching. Large wavelength shifts are observed for low pump powers due to the high nonlinearity of the amorphous silicon material and the strong mode confinement in the microcylindrical resonator. The threshold energy for switching is less than a picojoule, representing a significant step towards advantageous low power silicon-based photonic technologies.

We propose and demonstrate a novel approach to obtaining small core polysilicon waveguides from the silicon fiber platform. The fibers were fabricated via a conventional drawing tower method and then subsequently tapered down to achieve silicon core diameters of ~1 µm, the smallest optical cores for this class of fiber to date. Characterization of the material properties have shown that the taper process helps to improve the local crystallinity of the silicon core, resulting in a significant reduction in the material loss. By exploiting the combination of small cores and low losses, these tapered fibers have enabled the first observation of nonlinear transmission within a polycrystalline silicon waveguide of any type. As the fiber drawing method is highly scalable, it opens a route for the development of low cost and flexible nonlinear silicon photonic systems.

A hybrid silicon-core, silica-clad microspherical resonator has been fabricated from the semiconductor core fiber platform. Linear and nonlinear characterization of the resonator properties have shown it to exhibit advantageous properties associated with both materials, with the low loss cladding supporting high quality (Q) factor whispering gallery modes which can be tuned through the nonlinear response of the crystalline core. By exploiting the large wavelength shift associated with the Kerr nonlinearity, we have demonstrated all-optical modulation of a weak probe on the timescale of the femtosecond pump pulse. This novel geometry offers a route to ultra-low loss, high-Q silica-based resonators with enhanced functionality.

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Maghemite/reduced graphene oxide nanocomposite has been successfully deposited onto the surface of a gold-coated Dshaped optical fiber. The synergetic combination of gold, graphene, and iron oxide nanoparticles has shown enhancement of the resonance field and sensitivity of the fiberbased plasmonic sensor. Im particular, the sensor exhibited its capability to detect lead ions (Pb2+) in aqueous solution via monitoring the spectral response of the sensor probe to different concentrations of Pb2+. A sensor sensitivity of 1.2 nm per μg/L was attained at the lowest detected Pb2+ concentration, which is 0.001 ppm (limit of detection). This robust, compact, and highly sensitive fiber-based plasmonic sensor will be of a great interest for an in situ and real-time water safety environmental monitoring.

The use of a modified add-drop filter configured by the coupled two side rings for photon squeezing system is proposed. There are two forms of the coupling energies when photons travel around the micro -ring resonator that it is coupled by the two nonlinear side rings. They are the external disturbances known as the construction(creation, ̂ ) and destruction (annihilation, ̂) energy operators, which can disturb the traveling photons on the nonlinear microring resonator, from which the nonlinear behaviour called a four-wave mixing (FWM) is introduced by the coupled rings, which leads the system being unstable from the harmonic motion, from which the squeezed photons can occur. In a simulation, the obtained result of such a proposed behavior is confirmed by using the commercial Opti-wave and MATLAB software programs, whereas the suitable simulation parameters were chosen, the quantum harmonic squeezed photon theory is also reviewed, and the numerical details were given.

With the trend for green technology, the study focused on utilizing a forgotten herb to produce an eco-friendly coating. Andrographis paniculata or the kalmegh leaves extract (KLE) has been investigated for its abilities in retarding the corrosion process due to its excellent anti-oxidative and antimicrobial properties. Here, KLE was employed as a novel additive in coatings and formulations were made by varying its wt%: 0, 3, 6, 9, and 12. These were applied to stainless steel 316L immersed in seawater for up to 50 days. The samples were characterized and analyzed to measure effectiveness of inhibition of corrosion and microbial growth. The best concentration was revealed to be 6 wt% KLE; it exhibited the highest performance in improving the ionic resistance of the coating and reducing the growth of bacteria.