Magnetic wire: transverse magnetism in a one-dimensional plasmonic system.

We experimentally demonstrate magnetic wire in a coupled, cut-wire pair-based metasurface operating at the terahertz frequencies. A dominant transverse magnetic dipole (non-axial circulating conduction current) is excited in one of the plasmonic wires that constitute the coupled system, whereas the other wire remains electric. Despite having large asymmetry-induced strong radiation channels in such a metasurface, non-radiative current distributions are obtained as a direct consequence of interaction between the electric and magnetic wire(s). We demonstrate a versatile platform to transform an electric to a magnetic wire and vice-versa through asymmetry-induced polymorphic hybridization with potential applications in photonic/electrical integrated circuits.

Design of a Bragg fiber with large mode area for mid-infrared applications.

The design of an all-solid, soft glass-based, large mode area Bragg fiber for effective single mode operation with mode effective area exceeding 1100 µm(2) across the wavelength range of 2-4 µm is reported. The design adopts a new strategy to induce large differential loss between the fundamental and higher order modes for effective single-mode operation within few tens of centimetres length of an otherwise multimode fiber. In addition to having the potential for the targeted application in high power laser delivery systems; complemented by a zero dispersion wavelength at 2.04 µm and rapidly developing mid-IR optical sources, the proposed fiber should also be attractive for generation of high power, single mode and less divergent supercontinuum light over this mid-IR window.

Experimental demonstration of spectral broadening in an all-silica Bragg fiber.

We present the first report on experimental observation of nonlinear spectral broadening in an all-solid photonic band gap Bragg fiber of relatively large mode area approximately 62 microm(2). The theoretically designed Bragg fiber for this specific application was fabricated by the well known MCVD technique. Nonlinear spectral broadening was observed by launching high power femtosecond pulses of 1067 nm pump wavelength. These first results indicate that fabrication of such Bragg fibers, once perfected, should potentially serve as an alternative route for realization of supercontinuum light.

Seminumerical approach for modeling side-polished microstructured optical fiber-based devices.

We developed a simple seminumerical method to model, get design parameters, and estimate performance of side-polished microstructured optical fiber (SPMOF)-based devices. As an example, we analyze a SPMOF directional coupler and show good agreement between the available experimental results and our theoretically estimated characteristics of such a coupler. To further demonstrate the utility of our design approach, we also propose a new wavelength filter design based on the use of a SPMOF half-coupler, which is loaded with an overlay planar waveguide and should find applications as a gain-flattening filter for erbium-doped fiber amplifiers or as a bandstop filter, in general. To show the applicability of our approach even to surface plasmonic components, we also propose a SPMOF polarizer design, which could be formed by coating the top polished surface of a SPMOF half-coupler with a metal layer.

Role of Resonance Modes on Terahertz Metamaterials based Thin Film Sensors.

We investigate thin film sensing capabilities of a terahertz (THz) metamaterial, which comprises of an array of single split gap ring resonators (SRRs). The top surface of the proposed metamaterial is covered with a thin layer of analyte in order to examine various sensing parameters. The sensitivity and corresponding figure of merit (FoM) of the odd and even resonant modes are analyzed with respect to different thicknesses of the coated analyte film. The sensing parameters of different resonance modes are elaborated and explained with appropriate physical explanations. We have also employed a semi-analytical transmission line model in order to validate our numerically simulated observations. Such study should be very useful for the development of metamaterials based sensing devices, bio-sensors etc in near future.

Method to determine the optical properties of turbid media.

A novel method to determine the optical properties, namely, absorption coefficient, scattering coefficient, and anisotropy factor of turbid solutions, single constituent or multiconstituent, is presented. Turbid solutions of milk, ink, and a mixture of both were illuminated by a laser beam and measurements were carried out in scattered light. Experimental results were matched to the corresponding results of Monte Carlo simulation to obtain the optical properties of the turbid media.

Design of dispersion-compensating Bragg fiber with an ultrahigh figure of merit.

We report a novel idea for achieving highly efficient dispersion-compensating Bragg fiber by exploiting a modified quarter-wave stack condition. Our Bragg fiber yielded an average dispersion of approximately -1800 ps/(nm km) across the C band for the fundamental TE mode and an ultrahigh figure of merit of approximately 180,000 ps/(nm dB), which is at least 2 orders of magnitude higher than that of conventional dispersion-compensating fibers. The proposed methodology could be adopted for the design of a dispersion compensator across any desired wavelength range.

Design optimization of a dual-core dispersion-compensating fiber with a high figure of merit and a large effective area for dense wavelength-division multiplexed transmission through standard G.655 fibers.

We report design optimization in terms of index-profile parameters of a dual-core dispersion-slope-compensating fiber suitable for broadband dispersion compensation in standard G.655 and G.655b single-mode fibers over the C and L bands of fiber amplifiers and additionally over the S band for the G.655b fibers. It takes into account profiles that can be achieved with state-of-the-art fabrication techniques such as modified chemical-vapor deposition. Relatively high mode effective areas ensure the reduced sensitivity of the fiber to detrimental nonlinear effects when the fiber is integrated into a dense wavelength-division-multiplexed network. The theoretical figures of merit of these DCFs were found to be > or = 700 (ps/dB)/nm; furthermore, the estimated bend losses were also quite low, even for bend radii as small as 16 mm.