An optical nanocavity incorporating a fluorescent organic dye having a high quality factor

We have fabricated an L3 optical nanocavity operating at visible wavelengths that is coated with a thin-film of a fluorescent molecular-dye. The cavity was directly fabricated into a pre-etched, free-standing silicon-nitride (SIN) membrane and had a quality factor of Q = 2650. This relatively high Q-factor approaches the theoretical limit that can be expected from an L3 nanocavity using silicon nitride as a dielectric material and is achieved as a result of the solvent-free cavity-fabrication protocol that we have developed. We show that the fluorescence from a red-emitting fluorescent dye coated onto the cavity surface undergoes strong emission intensity enhancement at a series of discrete wavelengths corresponding to the cavity modes. Three dimensional finite difference time domain (FDTD) calculations are used to predict the mode structure of the cavities with excellent agreement demonstrated between theory and experiment

Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed

Efficient out-coupling and beaming of Tamm optical states via surface plasmon polariton excitation

We present evidence of optical Tamm states to surface plasmon polariton (SPP) coupling. We experimentally demonstrate that for a Bragg stack with a thin metal layer on the surface, hybrid Tamm-SPP modes may be excited when a grating on the air-metal interface is introduced. Out-coupling via the grating to free space propagation is shown to enhance the transmission as well as the directionality and polarization selection for the transmitted beam. We suggest that this system will be useful on those devices, where a metallic electrical contact as well as beaming and polarization control is needed

The optical properties of hybrid organic-inorganic L3 nanocavities

We report the fabrication of L3 nanocavities defined into a free-standing silicon nitride (SiN) membrane coated with a thin (10 nm) film of fluorescent red-emitting conjugated polymer. We find that structures both with and without the conjugated polymer are characterized by a number of different confined optical modes with quality factors ranging between 450 and 1200. We characterize the polarization of the modes and discuss the enhancement of emission intensity from both the SiN and the polymer using spectral imaging. © 2010 Optical Society of America

A one-dimensional photonic-crystal nanocavity incorporating a fluorescent molecular dye

We model the optical properties of a SiN based one-dimensional waveguide photonic crystal nanocavity with three tapered air holes as a function of the photonic crystal mirror fill factor using finite difference time domain calculations. We show that the Q -factor of this type of cavity has a strong dependence on the mirror fill factor, with a Q -factor as high as 35 000 predicted. Experimental studies on a range of representative structures whose surface is coated with a layer of a fluorescent dye confirm our modeling and reveal that such structures are characterized by a single optical mode having a Q -factor of 2000. © 2010 American Institute of Physics

SEXUAL EXPLOITATION AND ABUSE BY UN PEACEKEEPERS: THE PSYCHOSOCIAL CONTEXT OF BEHAVIOUR CHANGE

United Nations peacekeepers have been subject to allegations of serious sexual misconduct for many years. Such incidents of sexual assault perpetrated by peacekeepers have been documented over the years in a number of countries. The violation of codes of conduct, particularly regarding sexual exploitation and abuse, damages the image and credibility of a peacekeeping operation. Victims of sexual exploitation and abuse suffer sever physical and psychological consequences.The sexual exploitation of children by peacekeepers is particularly insidious. Educational interventions and training initiatives to bring about behaviour change to address sexual exploitation and abuse must take cognisance of the way in which social identities are shaped in response to the life challenges posed by the relevant social and material world in which peacekeepers find themselves