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A new scheme for unidirectional coupling of surface plasmon polaritons (SPPs) from freely propagating light into a metal-insulator-metal waveguide is proposed, which is composed of an asymmetric double-slit of different widths sandwiched by symmetric grooves. A theoretical model based on coupled-mode equations is developed to facilitate structure design and elucidate the underlying physical mechanism. With the model, the asymmetric double-slit with different widths is designed for unidirectional launching of SPPs with an ultrahigh extinction ratio of 44.8 dB at the wavelength 800 nm. A method of stepwise design is proposed for simplicity of design and convenience of analysis. Proof-of-principle demonstrations show that an ultrahigh extinction ratio of 37.1 dB and significant field enhancement for the proposed whole structure are obtained. In addition, an ultracompact plasmonic dichroic splitter based on the asymmetric double-slit with high extinction ratios of 24.2 and 21.8 dB at splitting wavelengths of 800 and 900 nm is achieved, and the lateral dimension of the plasmonic dichroic splitter is only 760 nm. [ABSTRACT FROM PUBLISHER]

Although the surface Plasmon resonance (SPR) sensor is a mature technology, currently, the sample temperature needs to be carefully considered and controlled because SPR signals vary with temperature. This poses a large challenge in the applications where the sample temperature changes during measurement or an SPR sensor operates in different environmental temperatures. This paper proposes and experimentally demonstrates, for the first time to our knowledge, a solution to simultaneously measuring refractive index and temperature based on conventional SPR sensors, thus, not only requiring no temperature control/calibration during the measurement but also enabling SPR sensors for in-situ operations. [ABSTRACT FROM PUBLISHER]

A new type of efficient and unidirectional optical coupler composed of periodic nanoslits milled in the metallic surface is proposed for the hybrid plasmonic waveguides. The operation principle is clarified and theoretically illustrated by using the coupled-mode model and the fully vectorial aperiodic Fourier modal method. The coupling efficiency of more than 50% and splitting ratios better than 18 dB at the incident angle θ= 12° could be achieved over the C-band ranging from 1530 to 1570 nm. [ABSTRACT FROM PUBLISHER]

We experimentally demonstrate a mechanism of broad-angle and efficient unidirectional excitations of surface plasmon polaritons (SPPs). By combining the plasmonic critical angle phenomenon and grating effects, unidirectional excitation of SPPs with broad incident angular width up to 25 ° and high extinction ratio better than 10 dB was experimentally demonstrated. A peak extinction ratio of 17 dB was achieved. The proposed structure was also numerically simulated showing good agreement with experimental measurement. The operation principle was numerically and experimentally clarified through compare and analysis. [ABSTRACT FROM AUTHOR]

A compact bidirectional polarization splitter based on two cascaded sub-gratings in a metallic-dielectric-air (MDA) waveguide is proposed and theoretically analyzed. The normally incident beam coupled to the MDA waveguide is split into left-going TE- and right-going TM-polarized modes by the structure. The operation principle is clarified and a coupled-mode model is developed for facilitating design. The polarization extinction ratio better than 33 dB and crosstalk less than -41 dB for TE-polarized mode and the corresponding 36 and -28 dB for TM-polarized mode are achieved at the operating wavelength 850 nm. [ABSTRACT FROM PUBLISHER]

We theoretically investigate a widely-used plasmonic structure composed of a nano-slit aperture surrounded by surface corrugations. A systematical semi-analytical theory in form of two nested coupled-mode models is developed to provide intuitive physical pictures. Based on the theory, figures of merit (FoMs) of the structures designed for normal and for oblique incidence/beaming are defined for the first time to incorporate the interlinks among key structural parameters, making global optimization simple and efficient. Both the theory and the FoMs are quantitatively validated with exhaustive calculations and shown to be highly accurate on performance prediction and structural optimization. With the theory and the FoMs, an efficient, effective and standard recipe is introduced for optimal structure design. We believe this work will help to understand the mechanisms of and to facilitate the design of such a structure in various configurations used in various applications. [ABSTRACT FROM PUBLISHER]

A theoretical model is presented for the scattering of light and surface plasmon polaritons (SPPs) by finite-size subwavelength metallic defects. Based on the decomposition of the scattered fields into SPPs and quasi-cylindrical waves (CWs), an SPP-CW model is developed to depict the multiple scattering of SPPs and CWs in finite-size defects using the elementary scattering processes in a single one. The involved elementary scattering of the CW, as well as the CW-related coefficients, which are difficult or even impossible to define and calculate according to classical scattering theory, is clarified. A close relationship between the scattering coefficients of the SPP and those of the CW has been pointed out and used to simplify the developed model. Compared to the corresponding pure SPP model and the fully vectorial computational data, the SPP-CW model is shown to be versatile and quantitatively accurate for finite-size defects such as grooves, ridges, slits or even hybrid systems of various geometrical parameters, over a broad spectral range from the visible to the thermal infrared regime. [ABSTRACT FROM AUTHOR]

A metal-clad optical polarizer with a resonant buffer layer has been investigated by the finite-element method in this paper. Important waveguide design parameters, such as the refractive index, thickness, interaction length, fabrication tolerance, and band-stop characteristics, have been analyzed in detail. Mode coupling within the polarizer and the losses due to coupling between the polarizer and the input and output waveguides are considered using the normal mode analysis. The loss behaviors of and modes are explained and the roles of the resonant buffer layer are interpreted. By using ultralow index layers, resonance, as well as its phase-matching conditions and excellent performance, has also been presented and discussed for this structure for the first time. Simulations show that high performance can be achieved in a wide range of the cladding thicknesses (ges 2 mum) and interaction length for both TE-pass and TM-pass polarizers. With optimized parameters under 3-mm length, it is possible to obtain a broadband TE-pass polarizer with an extinction ratio of more than 40 dB and insertion loss below 0.2 dB over 200 nm, and a TM-pass polarizer with an extinction ratio of more than 30 dB and insertion loss below 0.4 dB over 28 nm. [ABSTRACT FROM PUBLISHER]

A new family of two-dimensional optical orthogonal code (2-D OOC), one-coincidence frequency hop code (OCFHC)/OOC, which employs OCFHC and OOC as wavelength hopping and time-spreading patterns, respectively, is proposed in this paper. In contrary to previously constructed 2-D OOCs, OCFHC/OOC provides more choices on the number of available wavelengths and its cardinality achieves the upper bound in theory without sacrificing good auto-and-cross correlation properties, i.e., the correlation properties of the code is still ideal. Meanwhile, we utilize a new method, called effective normalized throughput, to compare the performance of diverse codes applicable to optical code division multiple access (OCDMA) systems besides conventional measure bit error rate, and the results indicate that our code performs better than obtained OCDMA codes and is truly applicable to OCDMA networks as multiaccess codes and will greatly facilitate the implementation of OCDMA access networks. [ABSTRACT FROM PUBLISHER]

We present diverse vestigial-sideband-filtering maximum-likelihood sequence estimation (DVSB-MLSE), a modification of MLSE, for residual chromatic dispersion (CD) compensation in nonreturn-to-zero (NRZ) on-off keying (OOK) systems. While VSB filtering can considerably increase residual CD tolerance of MLSE receivers, the performance of MLSE can be further enhanced by diverse reception, through which the MLSE module jointly equalizes samples from upper and lower VSB filtered signals. Simulation results show that compared to conventional MLSE, DVSB-MLSE increases the residual CD tolerance at 3-dB optical signal-to-noise ratio penalty by 110% in a 42.7-Gb/s NRZ-OOK system. [ABSTRACT FROM PUBLISHER]

Degree of polarization degradation due to intrachannel nonlinearity with different bit-rates and modulation formats is experimentally and numerically investigated. The degradation becomes obvious in 40 Gbit/s transmission, especially for intensity-modulated signals. It will deteriorate the effectiveness of polarization multiplexing and polarization interleaving transmission. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 312–314, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23062 [ABSTRACT FROM AUTHOR]

The generation of high-order Brillouin Stokes is experimentally demonstrated in 300 km all-Raman transmission with normal Raman pumps and without mirror reflection, and a longest ever fiber laser is implemented at the same time. The OSNRs of the two Brillouin Stokes after 300 km are both higher than 29 dB. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2939–2941, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22899 [ABSTRACT FROM AUTHOR]

The effect of group delay ripple in fiber bragg grating and polarization mode dispersion on the phase shift of recovered clock signal and the sampling time shift is theoretically and experimentally investigated in 42.8 Gbit/s WDM recirculating transmission, which may result in significant BER degradation in high speed transmission. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 3066–3068, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.22935 [ABSTRACT FROM AUTHOR]