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We experimentally demonstrate a new method to determine the polarization properties of piezoelectric nanocomposite materials using fiber-optic cantilever beam deflection principle. We used an optimized composition of BiFe0.9Co0.1O3 nanoparticles as a sample coated on a selected segment of the exit end of a single-mode optical fiber to devise the beam-deflecting cantilever assembly in a surrounding electric field. Performing series of experiments by systematically varying the associated parameters, namely coated length, coating thickness of deflecting fiber probe, polarization properties at different electric field intensities is determined. As an initial attempt, we devise a fiber-optic double-slit type arrangement and calculate the polarization values by measuring the fringe-width variation of interference pattern as a function of applied electric field. Through a progressive experimental development, we embed the fiber beam deflection transducer in a fiber-to-fiber signal transmission configuration. Polarization values are now determined in terms of transmitted power variation with applied electric field. The sensitivity is further enhanced by a cascaded assembly of cantilevers. We report a sensitivity ~ 0.067 kV/cm using our set-up and determine the polarization values that are known otherwise from the literature, thereby establishing the efficacy of this new approach.

The tight modal confinement property with circularly symmetric fundamental mode-field pattern of a ring structured photonic crystal fiber (PCF) is utilized to improve the laser threshold and output characteristics of existing fiber lasers. We perform a detailed study of continuous-wave lasing characteristics in such erbium-doped fiber host by varying associated geometrical and optical parameters towards achieving a high performance and short length fiber laser. A finite difference mode-convergence analysis is implemented to determine the required modal properties of the guiding host, which is then used to solve standard propagation rate equations. The laser properties of the structure considered is compared with equivalent regular triangular-lattice photonic crystal fiber illustrating a significant improvement in the characteristics of fiber lasers reported so far.

A simple one dimensional potential well model has been employed to understand the photoluminescence from ZnO QDs. The radius of the QDs being much larger than the Bohr radius, weak confinement effect was observed. UV-visible spectrum was used to calculate the band gap of the QDs. The value of the band gap also suggests that the confinement effect is very weak. We designated various energy levels corresponding to different emission peaks with different quantum numbers n. This study will help in understanding the photoluminescence from ZnO nanostructures in a different way.

We have investigated the modal birefringence behaviour of a near-elliptic core index-guiding photonic crystal fiber (PCF) intended for realizing high birefringence characteristics. For this analysis, we have devised a semi-vectorial finite difference (FD) algorithm in combination with the perturbation correction technique of mode calculation. The approach yields accurate results, simple to implement, and much faster than any of the existing methods. The effectiveness of our design analysis has been verified by comparing the results with otherwise known solutions. Using this analysis as a design recipe, we have realized PCF of reasonably high birefringence characteristics.

Plasmonic assisted enhancement of optical absorption within a thin layer of amorphous silicon (a-Si:H) by incorporating a periodic array of spherical metal nanoparticles on the front side of the a-Si:H layer has been demonstrated by solving Maxwell?s curl equations using a finite difference time domain (FDTD) method. For different particle sizes between 40?and 80?nm, the interparticle spacing has been optimized to yield maximum absorption of AM1.5G solar radiation. By increasing the interparticle coupling, a red-shift up to 280?nm is observed in the peak of broadband absorption behavior within a-Si:H layer. Meanwhile, a comparison between spherical Ag, Al and Au nanoparticles of fixed size is made with respect to the optical absorption enhancement within a-Si:H for the wavelength range from 400 to 800?nm from which we can choose the wavelength range over which a particular type of metal nanoparticle will be useful.