Photonic structures are commonly designed to manipulate scattered or emitted light. However, in recent years, they were demonstrated to affect a variety of phenomena, including chemical reactions, which lie outside the traditional electrodynamics domain. In this work, we have studied the effect of a Fabry–Perot cavity on the chemical reaction of practical importance—photodegradation of the semiconducting polymer 2,5-poly(3-hexylthiophene) (P3HT), which is the material of choice in organic photovoltaics. Experimentally, Fabry–Perot cavities, composed of two silver mirrors and filled with P3HT polymer, were photoexposed over tens of hours, and the concentration of the remaining thiophene rings (composing P3HT) was studied as a function of time. It has been found that in the regime of strong coupling with the cavity, characterized by one of the largest values of the Rabi splitting reported in the literature (1.0 eV), the normalized rate of photodegradation is reduced threefold, substantially larger than in the weak coupling regime reported in our recent study. This result adds to the toolbox of strong coupling phenomena and paves the road towards long-range control of chemical reactions and catalysis.

We present a unique compact model for oxide memristors based upon the concentration of oxygen vacancies as state variables. In this model, the increase (decrease) in oxygen vacancy concentration is similar in effect to the reduction (expansion) of the tunnel gap used as a state variable in existing compact models, providing a mechanism for the electronic current to increase (decrease) based upon the polarity of the applied voltage. Rate equations defining the dynamics of state variables are obtained from simplifications of a recent paper in which electronic processes (i.e., electron capture/emission) were combined with atomic processes (i.e., Frenkel-pair generation/recombination, diffusion) stemming from the thermochemical model of dielectric breakdown. Central to the proposed model is the effect of the electron occupancy of oxygen vacancy traps on resistive switching dynamics. The electronic current is calculated considering Ohmic, band-to-band, and bound-to-band contributions. The model includes uniform self-heating with Joule heating and conductive loss terms. The model is calibrated using experimental current–voltage characteristics for $\mathrm{Hf}{\mathrm{O}}_2$ memristors with different electrode materials. Though a general model is presented, a delta-shaped density of states profile for oxygen vacancies is found capable of accurately representing experimental data while providing a minimal description of bound-to-band transitions. The model is implemented in Verilog-A and tested using read/write operations in a $4\times 4$ 1T1R nonvolatile memory array to evaluate its ability to perform circuit simulations of practical interest. A particular benefit is that the model does not make strong assumptions regarding filament geometry of which scant experimental-evidence exists to support.

We have demonstrated a low-threshold surface-emitting plasmonic laser radiating two symmetrical beams (at 30° from the normal to the sample) characterized by a narrow (≤1 nm) spectral width, and explained its performance in terms of the distributed feedback mechanism. The results of our study provide an extra degree of freedom to the plasmonic laser design.

We have studied spectra and angular distribution of emission in Fabry–Perot cavities formed by two silver mirrors separated by a layer of poly (methyl methacrylate) polymer doped with rhodamine 6G (R6G) dye in low ( 20 g / l ) and high ( 200 g / l ) concentrations. The frequency of emission radiated to a cavity mode was larger at large outcoupling angles—the “rainbow” effect. At the same time, the angle of the strongest emission was also determined by the cavity size: the larger the cavity, the larger the angle. The angular distribution of emission is commonly dominated by two symmetrical lobes (located at the intersection of the three-dimensional emission cone with a horizontal plane) pointing to the left and to the right of the normal to the sample. Despite the strong Stokes shift in R6G dye, the branch of the cavity dispersion curve obtained in the emission experiment is positioned above the one obtained in the reflection (extinction) experiment. Some dye molecules are poorly coupled to cavity modes. Their emission has very broad angular distribution with the maximum at θ = 0 ∘ . The signatures of strong cavity–exciton coupling were observed at high dye concentration ( 200 g / l ) but not at low concentration ( 20 g / l ). The evidence of the effect of strong coupling on emission is exemplified by a strong difference in the angular distribution of emission in two almost identical cavities, one with and another without strong coupling. Most importantly, we have demonstrated the possibility to control the ground state concentration, the coupling strength, and the dye emission spectra with Q-switched laser pulses.

A Wavelength Division De-multiplexer has been proposed based on a hexagonal lattice 2D photonic crystal structure. The structure has been designed using GaAs rods, dielectric constant 11.4, which are suspended in air. The device has been proposed for De-multiplexing two wavelengths of 1.31 μm and 1.55 μm. The Plane Wave Expansion method and the Finite Difference Time Domain method have been utilized for simulating the photonic band-gap and results respectively. The localization property of photonic crystal has been exploited to guide the wavelengths in two different output paths thereby obtaining low crosstalk and more than 70% of transmission.

The objective of this study was to control the transmission, dispersion and, eventually, the nonlinearity of an optical fiber by intercepting and manipulating the evanescent field extending from the core to the cladding with a variety of plasmonic and metamaterial nanostructures. The access to evanescent waves is enabled by placing the core close to the flat surface of the cladding in the so-called D-shaped fiber design. In the first phase of the project, reported here, the numerical simulations of D-shaped fibers with deposited metal (Au) have been performed. We, furthermore, demonstrated that the fiber transmission can be controlled by highly concentrated rhodamine 6G molecules deposited onto the fiber’s flat surface.