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We experimentally demonstrate a novel ultrabroadband and wide-angle unidirectional coupling scheme by combining the coupling effect of single nanoslit and chirped grating effect. The operation principle is numerically and experimentally clarified through analysis and compare. Numerical analysis shows that the fabricated chirped-nanoslits grating could unidirectionally couple surface plasmon polaritons from free-space light over an ultrabroadband (1.3 $\mu$ m) and wide-angle ( ${\text{30}}^{\circ }$ ) ranges. Excellent unidirectional coupling performance with extinction ratio ER $>10$ dB (a peak value ER = 22 dB) over an ultrabroad operating bandwidth of 300 nm and wide angular range of ${\text{26}}^{\circ }$ is experimentally demonstrated.

An efficient and unidirectional optical coupling scheme for metal-dielectric-metal (MDM) waveguides with wide-angle and ultra-broadband efficiency is proposed and demonstrated. Based on joint effects of the plasmonic critical angle phenomenon (PCA), the zero-order grating resonance, and the first-order Fabry–Perot (FP) resonance of the MDM waveguide, the illuminated light could be efficiently coupled into MDM plasmonic waveguide with angular-full-width-half-maximum (AFWHM) widen to 50° over a broad wavelength range 750–1000 nm. The operation principle and performance of the structure are clarified and theoretically illustrated.

A new coupling scheme for unidirectional coupling of surface plasmons from free-space light over a broad-angle range is proposed and theoretically investigated. Firstly, the property of strong asymmetric excitation is found in the single wide defect, especially the single dielectric ridge, which is due to the excitation of asymmetric mode in the wide defect under oblique incidence. Then we show that the strong asymmetric excitation by single ridge still exists in the periodic dielectric ridge grating. By cascading the asymmetric mode excitation peak and the grating resonance angle peak, the angular-full-width-half-maximum (AFWHM) is broadened to $39^\circ$ . Finally, the AFWHM is further broadened to $52^\circ$ by utilizing the chirped ridge grating and a remarkable property of wide flat-top angular response is achieved.

An efficient plasmonic dichroic splitter based on periodic metallic nanoslits milled in the metal–dielectric–Si hybrid plasmonic waveguide is proposed and investigated. The backside incident photons illuminated on the dichroic splitting structure are coupled and launched into the hybrid plasmonic modes propagating to the left- or right-side depending on the wavelength. Proof-of-principle demonstrations show that the good coupling and splitting performances with coupling efficiency 0.5 and high splitting ratios 26.4 dB at wavelength 1310 nm (right:left power contrast), and 0.46 and 21.7 dB at wavelength 1550 nm (left:right power contrast) are achieved, respectively. The operation principle is clarified and the performance is discussed.

A compact unidirectional plasmonic coupler based on asymmetric cascaded nanoslits is proposed and theoretically analyzed. The incident photons illuminated on the structure are unidirectionally coupled into the metal–insulator–metal waveguide. The operation principle is clarified and a universal theoretical model based on coupled-mode equations is developed to facilitate structure design. Proof-of-principle demonstrations show that an ultrahigh extinction ratio ER $= 43.8$ dB at a specific wavelength and broadband of 160 nm covering a wide angular range from −20° to 15° with ER ≥ 10 dB are achieved.

A compact ultrabroadband coupling and binary encoding structure based on an array of aperiodic nanoslits cascaded by two different pairs of grooves in a metallic-dielectric-air waveguide is proposed and theoretically analyzed. The nanoslits array function as a broadband antenna to couple the incident lights into surface plasmon polaritons (SPPs) over an ultrawide wavelength range (spectral full-width-half-maximum >430 nm). The two ports composed of different grooves exhibit different transmission for the coupled multiwavelength SPPs. After traveling through different ports, the incident lights dropping in different wavelength ranges are differentiated and endowed with different logic state encodings. The operation principle is clarified and a coupled-mode model is developed for facilitating design.

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.

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.

We propose and numerically investigate a plasmonic triple-wavelength demultiplexing structure based on metal-insulator-metal waveguides with side-coupled nanodisk cavities. The structure consists of three output channels, each of which is sandwiched by two nanodisk cavities and functions as a dual stop-band filter. The operation principle and transmission characteristics are analyzed by using the temporal coupled-mode theory and the finite-difference time-domain method. Simulation results show that the demultiplexed wavelength of each channel can be effectively tuned by adjusting the geometrical parameters of the structure. The proposed structure will find potential applications in photonic-integrated circuits and ultracompact optical communication systems.

A new bidirectional polarization splitting coupler based on a metal thin film perforated with periodic slits and coated with dielectric is proposed and theoretically investigated. The back-side incident light coupled to the metal-dielectric-air waveguide is split and launched into TM plasmonic and TE photonic modes simultaneously. The operation principle is clarified and theoretically illustrated using the fully vectorial aperiodic Fourier modal method. Polarization extinction ratios better than 15 dB and crosstalk less than 15 dB are achieved for both polarizations over C-band ranging from 1530 to 1570 nm.

A novel grating coupling scheme with simultaneously broadband and wide-angle efficiency for unidirectionally coupling freely propagating light into a silicon waveguide is proposed and theoretically investigated. The coupling structure is composed of two cascaded subgratings with proper spectral and angular intervals. A semi-analytical theory based on coupled-mode model is developed to facilitate the design. Proof-of-principle demonstrations show that the spectral and angular full-width half-maximums (FWHMs) are simultaneously broadened to nearly three times at a specific wavelength or incidence angle, compared with the reference grating of the same number of periodic features. The spectral FWHM reaches 200 nm, covering E + S + C or C + L + U communication bands, and meanwhile, the angular FWHM is up to 8°; if the spectral FWHM is diminished to 40 nm only covering C band, the angular FWHM will be as large as 40° . This paper may be of great interest in related applications such as biochemical sensing and optical interconnect.

A compact plasmonic wavelength demultiplexing structure based on arrayed metal–insulator–metal (MIM) plasmonic nano-disk cavities is proposed and numerically investigated by utilizing finite-difference time-domain (FDTD) method. The structure consists of a bus waveguide perpendicularly coupled with a series of nano-disk cavities through slit-waveguides. A model based on resonator theory is used to design the operating wavelength of the structure. Simulation results show that compared with the directly side-coupled nano-disk structure, the narrower transmission linewidth of each channel could be obtained through the coupling between fore-end slit-waveguide and nano-disk cavity. The transmission wavelength and bandwidth of the structure can be tuned by adjusting the geometrical parameters and the refractive index of cavities. The proposed structure will be useful in ultra-compact optical devices for optical communications and computing.

A compact bidirectional polarization splitting antenna (BPSA) composed of a patterned metallic structure coated by a thin dielectric film is proposed and theoretically investigated. Using a polarization-selective array of grooves, the backside illuminated light transmitted through the central nanoslit is split and coupled into TM- and TE-polarized modes supported by the metal-dielectric-air (MDA) configuration. The operation principle of the structure is clarified and theoretically illustrated by utilizing the fully vectorial aperiodic Fourier modal method (a-FMM). Numerical simulations show that insertion losses (ILs) less than 4 dB, polarization extinction ratios (PERs) better than 18 dB, and crosstalk (CR) less than -18 dB are achieved for both polarizations in the wavelength range 1510-1570 nm. The structure will find potential applications in highly integrated polarization diversity systems and photonic integrated circuit.

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.

This article presents a comprehensive study of burst assembly in optical burst switching (OBS) networks. This investigation aims to provide a unified study of burst assembly algorithms. After analyses of conventional assembly algorithms, we present an adaptive burst assembly algorithm: data-length time-lag product assembly algorithm. Numerical results show that the proposed algorithm takes the real-time traffic state into account to adapt burst length and its injected intervals. It obtains a more acceptable performance. Moreover, we investigated the impact of burst assembly applied at the edge of OBS networks. We analyze the Hurst parameter of the input traffic to the output traffic that results from the burst assembly. Two formulas are presented to describe changes of the Hurst parameter. Theoretical results are validated through extensive simulations in time-based, length-based, and adaptive assembly algorithms, respectively.

In wavelength division multiplexed optical networks each connection is assigned a light-path. Given a set of connection requests, how to set up a light-path for each of them is called the static routing and wavelength assignment (RWA) problem. The physical networks impose significant effects on the number of wavelengths required to accommodate all the connections as light-paths are directly set up on it. Wavelength requirements in the small-world and scale-free networks are investigated in this paper for the first time to the best of our knowledge. The two important characteristics of networks are considered: average shortest path length and 1-shell structure. Wavelength requirements in the case of network evolution are investigated, too. Mean light-path length is proved to be directly proportional to the average shortest path length of networks. Simulation results have shown that fewer wavelengths are required in networks with smaller average shortest path lengths, and the rate of increase of the number of wavelengths required is smaller too while traffic load and network size increasing. The emergence of 1-shell structure may result in the increase of the number of wavelengths required due to lack of flexibility in 1-shell structure. The larger the cardinality of 1-shell is, the more wavelengths the network requires.

Optical burst switching (OBS) is a promising technology which is able to well support bursty traffic and is also technically mature. One critical issue in OBS networks is burst contention. Several methods have been proposed to solve contention such as wavelength converters and fiber delay lines. Among those methods, routing is relatively cost-effective and technically tractable and has been extensively researched. A framework for evaluation the strength of this method is presented in this paper. As routing is a fundamental issue in optical networks and not only confined to OBS, the framework is applicable to a class of connectionless and non-buffer all-optical networks. Through comprehensive analysis of the relation between the total traffic load offered to the network and the traffic load on each link together with some mathematical skills, a lower bound on the burst loss probability is figured out. Extending it by minimizing the lower bound over all reasonable topologies, another lower bound is worked out. With the help of the two lower bounds, comprehensive prospect on the effectiveness of routing and network topologies in reducing the burst loss probability is shown for the first time to the best of our knowledge.

We propose a hybrid C-band erbium-doped fiber amplifier (EDFA) and L-band Raman fiber amplifier (RFA) using a single pump laser diode. The optimum pump sharing ratio to EDFA/RFA is 1/10 with a total pump power of 660 mW. Using multiple fiber Bragg gratings (FBGs) with various reflectivities at different positions along the dispersion compensation fiber, the optimum dispersion compensation and power equalization for C + L-band channels are simultaneously realized. With an input power of −20 dBm/ch, the signal power variation among the channels is reduced from 9.8 dB to less than ±0.5 dB. Two pump reflectors are introduced to increase the pumping efficiency.

The wide field-of-view (FOV) optical receiver has many advantages in optical wireless communication, sensing and detection. However, the FOV is limited by some tradeoffs of the receiver’s components employing conventional optical devices. Furthermore, present mechanisms to extend the FOV are not effective. To realize the wide FOV receiver effectively, we propose surface plasmon polaritons (SPPs) as the potential candidate. Two examples are presented to lively illustrate SPPs’ striking power to offer unexpected solutions to conventional problems. It is shown that unusual conditions should be explored to make use of SPPs under some circumstances. Excitations of localized SPPs, which are independent of the incidence angle, are suggested as the mechanism for the wide FOV receiver. Some progress in the optimization of SPPs’ excitation at oblique incidence is also reported.

In future high-capacity wavelength division multiplexed (WDM) optical networks, the failure of a network component such as a fiber link can lead to severe disruption in the networks’ traffic. Hence, it is imperatively important to provide fast and full protection in WDM optical networks. In this paper, we propose a new approach, called shared preconfigured protection cycles (shared-p-cycles), for the design of survivable WDM networks. We develop an integer linear program (ILP) formulation to solve the problem of shared-p-cycles design for WDM networks with and without wavelength conversion. Numerical results show that the shared-p-cycles design is more efficient in the use of spare capacity and requires much less spare capacity than the conventional p-cycles design.

A novel nonlinear electrical equalizer (NLEE) based on Volterra theory is proposed for mitigating intra-channel nonlinearities in pseudo-linear coherent optical communication systems. According to the temporal matching condition of intra-channel nonlinear pulse interactions, we just select specific nonlinear terms and reduce the computation complexity considerably. Numerical simulations of 10GBaud coherent quadrature phase-shift keying (QPSK) transmission show that the simplified NLEE can efficiently mitigate intra-channel nonlinearities.

Electrical post-compensation of intrachannel nonlinearities in 10GBaud coherent QPSK transmission systems is proposed. The channel inversion method is implemented with a coarse split-step Fourier algorithm through digital signal processing at the receiver side. Simulation results show that simultaneous compensation of intrachannel nonlinearities and chromatic dispersion can be achieved with much simplified signal processing structure. The required optical signal-to-noise ratio at certain bit error ratio is remarkably reduced when the intrachannel nonlinearities induced impairments are dominant.

In transport control protocol (TCP) over optical burst switching (OBS) networks, TCP window size and OBS parameters, including assembly period and burst dropping probability, will impact the network performance. In this paper, a parameter window data dropping probability(WDDP), is defined to analyze the impact of the assembly and the burst loss on the network performance in terms of the round trip time and the throughput. To reduce the WDDP without introducing the extra assembly delay penalty, we propose a novel TCP window based flow-oriented assembly algorithm dynamic assembly period (DAP). In the traditional OBS assembly algorithms, the packets with the same destination and class of service (CoS) are assembled into the same burst, i.e., the packets from different sources will be assembled into one burst. In that case, one burst loss will influence multiple TCP sources. In DAP, the packets from one TCP connection are assembled into bursts, which can avoid the above situation. Through comparing the two consecutive burst lengths, DAP can track the variation of TCP window dynamically and update the assembly period for the next assembly. In addition, the ingress node architecture for the flow-oriented assembly is designed. The performance of DAP is evaluated and compared with that of fixed assembly period (FAP) over a single TCP connection and multiple TCP connections. The results show that DAP performs better than FAP at almost the whole range of burst dropping probability.

We propose an all-optical modulation formats combination scheme that merges an amplitude-shift keying (ASK) signal and a differential phase-shift keying (DPSK) signal into a single differential phase amplitude-shift keying (DPASK) signal based on parametric amplification in a highly nonlinear fiber. By optimizing the power of the ASK channel, formats combination of ASK and DPSK to DPASK signal is successfully demonstrated by computational simulation. The demodulation process of the generated DPASK pulses is investigated and the relationship between optical signal-to-noise ratio (OSNR) penalty and the input ASK power is presented. The proposed scheme may be used for increasing spectral efficiency and all-optical logic device.

In terms of the growth rate, network capacity is slower than network traffic. To solve the mismatch between them, utilization of available capacity can be maximized to provide “best-fit” service for emerging applications (e.g., eBanking, Peer-to-Peer (P2P) file exchanges, etc.). To satisfy such a requirement, we propose a three-dimensional label scheduling algorithm (TD-LSA), which is a distributed scheduling approach powered by central databases. In the proposal, all connections are provisioned in three dimensions (i.e., space, time and wavelength) in a distributed way and uniquely identified by three-dimensional labels. And in this way a three-dimensional connection is more robust than a single-dimensional connection because the three-dimensional approach can avoid potential scheduling conflicts as much as possible by using central databases in a network. Thus, the central databases can reduce bandwidth consumption and offer “best-fit” service for three-dimensional connections. Furthermore, in order to further reduce bandwidth consumption and to match with a priority of traffic, K-least hop first path (K-LHPF) and a rescheduling mechanism are applied to our proposal. Simulation experiments demonstrate that our proposal achieves the expected performance gain against existing alternates.

Due to the bufferless nature of OBS networks, contention will unavoidably occur in core nodes. When the retransmission scheme is introduced into OBS networks, the bursts in the contention will be dropped selectively according to the drop policy adopted in core nodes, and retransmitted by edge nodes. In this paper, we proposed a drop policy based on Hop Number, in which the bursts with the larger total hop number will be given the higher priority in the contention. Taking the retransmission cost into account, we proposed another novel drop policy based on Hop Number Factor. Meanwhile, in edge nodes, multiple thresholds are also proposed to limit the unnecessary retransmission, and ease the deteriorated network performance. Both theoretical analyses and simulation results show that the proposed mechanisms can reduce the burst loss rate and the round trip time effectively, and improve the throughput significantly in TCP over OBS networks with retransmission.

We present the principle of cascade arrangement of irregular optical phased arrays. The optical phased-array beam deflector comprises arrayed optical waveguides that are spaced irregularly and arranged in a two-stage cascade. Relations between optical path differences and corresponding center-to-center spacings among elements in each stage are found, and phase matches between the two stages are achieved. Simulation shows a wide scanning angle with dramatically suppressed sidelobes.

A new family of two-dimensional variable-weight and constant-length optical orthogonal codes (2D VWOOCs) is proposed, and the code cardinality and BER performance for the corresponding OCDMA system are analyzed in this article. It is shown that the cardinality of 2D VWOOC is larger than that of constant-weight 2D OOC and close to the upper bound in theory. In an OCDMA network, the users employing 2D VWOOC codewords with larger Hamming weight outperform the users using 2D VWOOC codewords with smaller Hamming weight in bit-error-rate performance. Therefore, the OCDMA network employing 2D VWOOC can support diverse quality-of-services (QoS) classes and multimedia services, and make the better use of bandwidth resources in optical networks.

We propose a simple and stable structure to realize a tunable negative coefficients microwave photonic notch filter. A 3 × 3 coupler based Sagnac loop interferometer with an asymmetrically placed phase modulator is used to acquire the notches. Our system is simply implemented and with good stability. Theoretical analysis and experimental results are presented and show a good agreement. The structure is proved to be a robust filter with more than 35 dB rejection deep notches.

In this article, an M-code keying OCDMA system with parallel encoders/decoders is presented and its security performance is quantitatively analyzed. Under brute-force searching techniques, the formula about the average searching time is derived. The bit-correct-interception possibilities for tapping individual and multiple users’ signals are calculated, respectively. By analysis, it is shown that the security performance of an OCDMA system can be enhanced by employing M-code keying.

By using the coupled steady-state equations, we have numerically studied the characteristics optimization of Raman fiber amplifier (RFA) in a signal/pump double-passes-the-gain-medium scheme. The simulation results are in very good agreement with those of experimental data. Given a constant pumping power, the length of dispersion compensation fiber (DCF) in a RFA could be determined. The optimum design shows that the best length of the DCF is at around 3.8 ± 0.2 km in our study. This could provide both the highest signal output power and the lowest noise figure among all conditions we choose.

We report on a novel micro torsion mirror actuated by a compound electrostatic driving structure. The compound driving structure is made up of a planar plate drive and a vertical comb drive. The device is fabricated in SOI substrate by using a bulk-and-surface mixed silicon micromachining process. As demonstrated by experiment, the novel driving structure can actuate the mirror to achieve large-range continuous rotation as well as spontaneous 90° rotation induced by the pull-in effect in a voltage control fashion. The continuous rotating range of the micro torsion mirror is increased to about 46° at an increased threshold voltage. The measured threshold voltage ranges of the mirrors with torsion springs of 1 μm and 0.5 μm in thickness are 390–410 V and 140–160 V, respectively. Theoretical modeling is carried out to compare with the experiment. The optical insertion loss has also been measured to be −1.98 dB when the mirrors serve as digital optical switches in a 2 × 2 array form.

A New random access protocol for OC-DMA networks is proposed in this paper. Employing a new mathematical model, namely the processor-sharing system, steady-state throughput ratio and average delay of OCDMA networks are calculated. The results reveal that our protocol outperforms other existing protocols. Meanwhile, we investigate the performance of OCDMA networks by altering the code parameters, i.e., length and weight, and the maximum number of active users in the system, corresponding results are indeed consistent with the practical situation. In addition, the analysis is simplified compared with the conventional Markov chain model. Thus the processor-sharing system is truly applicable to model OCDMA networks.

An optical waveguide structure, which increases the far fleld radiation angle two times than that of conventional flber, is designed and analyzed for the research of optical phased array. The structure improves the scanning scope of the optical flber phased array efiectively through designing the shape and the refractive index proflle of the single mode flber. Far fleld characteristic of this structure is analyzed using FD-BPM and the Fraunhofer difiraction theory. DOI: 10.2529/PIERS070125063744

For the purpose of reducing the complexity and cost of optical large-scale cross-connect, wavelengths are grouped into wavebands or fiber to be switched as a single entity, which is called multi- granularity switching. However, it introduces more complexity into the routing and wavelength assignment problem. In this paper, we propose a novel graph model for describing the states of the multi-granularity switching WDM networks. Based on the model, the dynamic routing and wavelength assignment problems for multi-granularity traffic can be solved jointly, and different on-line wavelength grooming policies can be achieved simultaneously. By simulation, we compared the performance of our algorithms under different policy and different percent of fibers for fiber switching. The result proved that our algorithms yield better performance than those deal with the routing and wavelength assignment separately.

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.

Although routing schemes based on global knowledge make most optimal routing decisions, they will occupy many resources to keep the state information of the network up-to-date. In this work, we describe a fuzzy least-congested path (FLCP) routing algorithm based on hierarchical information. Simulation shows that the blocking probability using FLCP is very near to the blocking probability using the least-congested path routing (LCP) algorithm based on global information. Under heavy traffic load, the FLCP algorithm is superior to the exhaustive algorithm (EA) and the LCP algorithm with unit information cost. The FLCP algorithm provides better routing, even with incomplete information. Thus, the algorithm requires less information of the network, particularly under heavy traffic load. In addition, an improved remote-path routing approach is provided to reduce the blocking probability of connection requests to a node that is many hops away from the source node.

Express train transportation is becoming a major tool for carrying approximately one million passengers daily in China today. To provide broadband information services for train passengers, the greatest challenge is achieving a seamless handover solution to guarantee wireless service continuity. This motivates us to incorporate sensor technology into Radio over Fiber architecture to construct an Express Train Access Network (ETAN), where the deployed sensor network captures the train movement status, which can indicate the wireless signal strength. Since the train moves on a fixed rail with fixed direction, it is possible to form an intelligent handover decision system, in which a critical movement state can exactly trigger an optical switch unit in the central station to carry out the handover procedure. Theory analyses and simulation results demonstrate that the proposed architecture can perform handover within 22 ms at a train speed of 350 km/h, providing wireless services for users without disruption, even for a cell radius as small as 100 m.

We demonstrate the long distance transmission of single-carrier frequency division multiple address signals by directly-modulated optically injection-locked vertical-cavity surface-emitting laser. Transmission distance as long as 50 km is achieved at 5 Gb/s (2.5 Gb/s for each user) through data pattern inversion and higher frequency response gain under optical injection locking.

A novel coupling scheme for unidirectional coupling of surface plasmons over a broad-angle range is proposed, the large AFWHM up to 60o is achieved by cascading the grating resonance angle peak and the asymmetric excitation peak.

A novel scheme to realize compact unidirectional plasmonic antenna with ultra-high extinction ratio ER=43.1 dB and broadband of 200 nm covering a wide angular range from −17° to 15° with ER>10 dB is proposed.

This paper is contributed to discuss the impacts of group velocity dispersion, nonlinear Kerr effect and polarization mode dispersion in optical fibers. Using split-step Fourier method, we first analytically analyze that the interaction of Kerr effect and polarization mode dispersion results in the pulse asymmetric spectra. Then we study that polarization mode dispersion and group velocity dispersion play their roles independently, and that, depending on the relative magnitudes, the two factors affect the pulse differently. Finally, we research the combined impacts of group velocity dispersion, Kerr effect and polarization mode dispersion. Detailed investigation reveals that the combined effects are different in anomalous and normal group velocity dispersion regime. We point out that increased Kerr effect can suppress the impact of polarization mode dispersion in anomalous chromatic dispersion regime, and that, for the given values of incident power and polarization mode dispersion, anomalous group velocity should be large enough for the polarization mode dispersion to be effectively suppressed by the Kerr effect.

Based on the metallic-dielectric high contrast gratings, we proposed two new different schemes to achieve the unidirectional coupling of incident free-space light into the plasmonic waveguides. Using the cascaded metal-air subgratings (structure 1) or metallic-dielectric subwavelength periodic gratings (structure 2), the ultra-broadband and wideangular SPPs excitation could be both achieved. The operation principle and performance of the structures are analyzed and discussed, respectively.

We report an experimental demonstration of optical single-sideband (SSB) modulation in 60-GHz radio-over-fiber systems based on an injection-locked distributed-feedback (DFB) laser. Two heterodyning optical modes with 60-GHz spacing are injected into the DFB laser and one of them is used to lock the DFB laser. When the DFB laser is directly modulated, the modulation index of the locked mode is 15 dB larger than that of the unlocked one. The 2.5-Gb/s data transmission at 60 GHz is successfully achieved over 50-km standard single-mode fiber using the proposed SSB scheme.

Owing to the fine-granularity and the separation of control and data plane, OBS technology has the potential to support Grid applications. In this letter, a general analytical model is established to analyze the impacts of the influential factors of both TCP and OBS layers on the performance of Grid-OBS networks ail-roundly. The extensive simulation studies are also conducted. Both the analytical and simulation results show the same trends.

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.

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

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

By recycling the residual pump power, performance improvements of parallel type C + L band erbium-doped fiber amplifier are demonstrated. For C-band branch, the average gain and noise figure are enhanced by 2.0 dB and decreased by 1.1 dB, respectively. Whereas for L-band branch, the average gain is raised by 0.5 dB and noise figure is lower by 0.3 dB. Bit error rate performance is verified with negligible power penalty of 0.3 dB for the proposed C + L band EDFA. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1953–1955, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21833