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With phase-sensitive optical time-domain reflectometry (Φ-OTDR), an optic fiber can be used as a distributed vibration sensor to perceive the external disturbance along the fiber through the phase variation of the Rayleigh backscatter light. However, due to the inevitable interference fading phenomenon, the signal-to-noise ratio (SNR) of Rayleigh backscatter light at certain points is insufficient, thus affecting the fidelity of vibration sensing. In this paper, we propose the spectrum extraction and the rotated-vector-sum (SERVS) method to suppress the interference fading in the pulse-intensity-coding Φ-OTDR, which applies Golay complementary sequence through acousto-optic modulator (AOM). Benefited from the easier implementation, the experimental results demonstrate that the percentage of fading points can be reduced from 2.98% to 0.33% significantly and the standard deviation of differential phase is also decreased from 0.6556 rad to 0.2901 rad. Also the minimum level of averaged power spectral density (PSD) of the differential phase at whole locations along the fiber is reduced about 6 dB/Hz effectively. For the demodulated disturbance signal, no influence on the SNR is observed thus it maintains a SNR improvement of 8.6 dB compared to the traditional single pulse Φ-OTDR system, achieving a noise floor of 2.38 pϵ/√Hz.

In this paper, passive generation of the multi-wavelength parabolic pulses (PPs) in tapered silicon nanowires (TSNs) is numerically investigated. The coupled inhomogeneous nonlinear Schrödinger equation (INLSE) is derived in the context of TSN to model the multi-wavelength PP generation. The TSN is designed based on the well-known self-similar theory that the group-velocity dispersion is decreased while the nonlinear coefficient is unchanged along the propagative direction. While the pump wavelengths for three input pulses are specially set with equal intervals of 18, 12, and 6 nm, the time-domain profiles are aligned at the same position. Simulation results show that except for wavelength interval, the waveguide length is also a critical factor that influences the quality of generated PP. Both of them reshape the pulse profile by the means of walk-off effect which depends on the cross-phase modulation between multiple pulses. By properly optimizing the input parameters of Gaussian pulses as well as the center wavelength interval and TSN length, we prove that the generation of two- even three-wavelength PPs with high-quality is feasible.

A graphene-coated two-layer dielectric loaded surface plasmon polariton (GTDLSPP) rib waveguide is designed. The mode characteristics and electro-optic (EO) modulation performances of the four hybrid plasmonic modes (HPMs) in the designed waveguide are simulated by using the finite element method. The simulation results show that a 103 mm-scale propagation length and an effective mode field area of ~λ2/1333 are obtained by adjusting the bias voltage. The EO wavelength tunings are -68.6, -42.0, -49.7, and -11.1 nm/V for the HPM 1, HPM 2, HPM 3, and the peak 2 of HPM 4, which are two orders of magnitude larger than those of other EO modulation structures. For the peak 1 of the HPM 4, the EO wavelength tuning is the piecewise linear. For a 150-μm long waveguide, the modulation depths of ~98.7, ~87.9, and 99.5%, and FWHMs of ~450, ~100, and ~42 nm can be achieved for the HPM 1, HPM 2, and HPM 3. For the HPM 4, there are two peaks in the transmission spectrum. The modulation depths are ~97.3 and 75.2%, and FWHMs are ~92 and ~34 nm for the peaks 1 and 2. There is a tradeoff between the modulation depth and FWHM for different waveguide lengths. The GTDLSPP rib waveguide designed has small size, high modulation depth, broad bandwidth, and compatibility with the CMOS technology, soit has potential applications in the EO tunable devices, optical interconnects, and optical switches.

Supercontinuum (SC) with broad bandwidth and high coherence is crucial in the SC-based frequency comb source generation. In this paper, we numerically investigate the mid-infrared (MIR) SC generations with the three optical modes (TE00, TE10, and TE20) in a multimode chalcogenide (As2Se3) strip waveguide. The waveguide structure is carefully engineered to ensure that the pump pulses are propagated in the normal dispersion regions of the considered three optical modes. Highly coherent and octave-spanning MIR SCs are generated when the optimized pump pulse with 80-fs pulse duration, 3-kW peak power, and 3-μm center wavelength is used. Moreover, the nonlinear dynamics of the SC generation are numerically analyzed. Finally, the SC-based frequency combs are numerically demonstrated when a pulse train with a repetition rate of 50 MHz is used as the pump source and launched into the multimode As2Se3-based strip waveguide. It is believed that the generated MIR SC and SC-based frequency comb sources have important applications in biophotonics, metrology, and sensing.

A simple optic-fiber Fabry-Perot (FP) sensing technique was proposed and experimentally investigated by using polymer material to connect the ends of two singlemode fibers. Four different polymer materials (benzocyclobutene (BCB), UV88 (Relentless, China), Loctite3525 (HenKel, Germany), and NOA68 (Norland, USA)) filling the FP cavity were used to comparatively study the sensing performance of temperature, strain and refractive index. The result shows that the FP sensor with BCB has excellent repeatability with good linear response to temperature in a wide range from room temperature to 250 °C, which is much larger than that of other three materials (2)) and the best repeatability among the four polymer materials.

Helically twisted photonic crystal fibers (HT-PCFs) provide additional opportunities for controlling the light propagation characteristics and improving the sensing performances. In this paper, a toluene and gold wire-filled HT-PCF was proposed and designed for high sensitivity temperature sensing. The influences of the structure parameters on the confinement loss, sensitivity, and resolution of the proposed HT-PCF were investigated. For the optimized HT-PCF, the average sensitivity is as high as 14.35 and 17.29 nm/℃ in the temperature range of −20 to 20 ℃ and 20 to 70 ℃, respectively. Moreover, the proposed HT-PCF-based temperature sensor is insensitive to the hydrostatic pressure. Finally, the detailed fabrication process of the toluene and gold wire-filled HT-PCF temperature sensor is proposed. It is believed that the proposed HT-PCF temperature sensor has potential applications in the fields of the environmental monitoring, medical diagnostics, etc.

In this work, a polarization beam splitter (PBS) based on surface plasmonic resonance is proposed and realized in a designed photonic crystal fiber (PCF). The PCF consists of two kinds of air holes with different diameters. Two solid silica cores near the center of the PCF are established by removing the cladding air holes. A gold film is plated at the external surface of the central air hole of the PCF to excite the surface plasmonic resonance. In order to minimize the length and improve the operation bandwidth of the PBS, the influences of the transversal structural parameters of the PCF are investigated in the context of both X and Y polarization beams. It was found that a 123.6-μm-long PBS with an operation bandwidth of 314 nm could be realized after the global optimization of five structural parameters. The proposed PBS may have potential applications in micro-/nano-optical systems for sensing and communications.

In this paper, a surface plasmon resonance (SPR)-based photonic crystal fiber (PCF) sensor is proposed for simultaneously measuring the refractive index (RI) and temperature. In the design, the central air hole and external surface of the proposed PCF are coated with gold films, and an air hole is filled with the temperature-sensitive material (TSM). By introducing the inner and outer gold films and TSM, the RI and temperature can be measured simultaneously at different wavelength regions. The simulation results show that the average wavelength sensitivities of the proposed SPR-based PCF sensor can reach 4520 nm/RIU and 4.83 nm/°C in the RI range of 1.35~1.40 and a temperature range of 20~60 °C, respectively. Moreover, because of using the different wavelength regions for sensing, the RI and temperature detections of the proposed SPR-based PCF sensor can be achieved independently. It is believed that the proposed SPR-based PCF RI and temperature sensor has important applications in biomedicine and in environmental science.

In this paper, we propose an in-phase/quadrature (IQ) imbalance estimation scheme for mixed transmitter (Tx) and receiver (Rx) IQ imbalance in the optical coherent transmission system. The proposed scheme is based on traditional IQ imbalance compensation algorithm Gram-Schmidt orthogonalization procedure (GSOP) and the proposed geometric construction method (GCM). In the actual transmission system, frequency offset (FO) and phase noise (PN) are recognized as part of received signal, which has an effect on the estimation of IQ imbalance. At the beginning of the proposed scheme, the GSOP algorithm is used to estimate and compensate Rx IQ imbalance according to the statistical characteristics of the received signal, then standard frequency offset compensation algorithm and k-means clustering aided blind phase search (BPS) algorithm are used to compensate FO and PN respectively. Finally, the proposed method GCM is used to estimate Tx IQ imbalance. 34 Gbaud QPSK and 16QAM signals are experimentally performed to demonstrate the proposed IQ imbalance estimation scheme, the results show the proposed scheme has accurate estimation capability with low estimation algorithm complexity.

In this paper, we numerically demonstrate efficient spectral compression (SPC) of wavelength-shifting soliton in a chalcogenide strip waveguide. It is found that the profiles of group-velocity dispersion (GVD) and Kerr nonlinearity play key roles in determining SPC. After calculating the dispersion of Kerr nonlinearity and Raman spectrum for three kinds of chalcogenide materials, Ge11.5As24Se64.5 is chosen as the material for designing the chalcogenide strip waveguide (CSW). The geometric parameters of CSW are optimized to obtain the desired GVD and Kerr nonlinearity. Simulation results show that in the designed CSW, an input spectrum width of 52.04 nm can be compressed to 7.23 nm along with wavelength shift of 17 nm when the input peak power is 25 W. With the input peak power increasing to 75 W, the SPC is slightly weakened, but wavelength shift can be up to 190 nm. The proposed CSW is applied to integrated all-optical quantization and an effective quantization number of 3.66-bit is achieved. It is expected that our research results can find important applications in on-chip integrated spectroscopy, all-optical signal processing, etc.

Spectral compression (SPC) can be used for generating narrow bandwidth and wavelength-tunable light sources, which have important applications in optical communication system, spectroscopy, and nonlinear microscopy. In this paper, we numerically demonstrate the high-degree SPC of the chirp-free femtosecond pulse at wavelength 2.4 μm in a 6-cm long adiabatically suspended silicon waveguide taper. The silicon waveguide taper is designed with a dispersion-increasing profile along the propagation distance z. Simulation results show that the SPC factor can be up to 10.9, along with the brightness-enhanced factor of 8.0 and negligible sidelobe. The impacts of the higher order dispersion, higher order nonlinearity, losses (including linear and nonlinear loss), and variation of Kerr nonlinear coefficient along z on the SPC are also investigated. It is found that variation of Kerr nonlinear coefficient γ(z) and linear loss are the dominant perturbation to the degradation of the SPC performance.

Recently, high-speed optical transmission using single-side-band (SSB) modulation with Kramers-Kronig (KK) scheme has gained great attention due to its high spectral efficiency (SE) and capability of electronic chromatic dispersion compensation (CDC), which can be widely employed in optical metro networks as a promising transmission scheme. To our knowledge, the carrier-signal power ratio (CSPR) is the key parameter to SSB-based systems and the optimum CSPRs can vary distinctly in different SSB modulation schemes. In this paper, the SSB-based KK systems with four kinds of SSB signal generation schemes are investigated, i.e. optical carrier-assisted SSB (OCA-SSB), virtual carrier-assisted SSB (VCA-SSB), SSB subcarrier modulation (SSB SCM) with IQ modulator (IQM) and with dual-drive Mach-Zehnder modulator (DDMZM) respectively. Here, the detailed theoretical derivations of these modulation processing are given and the theoretical relationship between device parameters and the CSPR has been further studied for the different SSB schemes. In order to verify those theoretical analyses, a 224-Gb/s direct detection (DD) transmission with SSB 16-ary quadrature amplitude modulation (16-QAM) signal has been demonstrated based on four SSB generation methods. The results show that theoretical derivations are closely consist with numerical analysis, such as $V_{bias}$ in the scheme of SSB SCM with IQM and optical modulation index (OMI) in SSB SCM with DDMZM. Therefore, our research can provide a theoretical guidance of appropriate device parameter configuration so as to achieve the optimum performance for SSB systems.

Abstract A polarization-dependent all-fiber comb filter based on a combination effect of multimode interference and Mach-Zehnder interferometer was proposed and demonstrated. The comb filter was composed with a short section of multimode fiber (MMF) fusion spliced with a conventional single mode fiber on the one side and a short section of a different type of optical fiber on the other side. The second type of optical fiber is spliced to the MMF with a properly designed misalignment. Different types and lengths of fibers were used to investigate the influence of fiber types and lengths on the performance of the comb filter. Experimentally, several comb filters with free spectral range (FSR) values ranging from 0.236 to 1.524 nm were achieved. The extinction ratio of the comb filter can be adjusted from 6 to 11.1 dB by varying polarization states of the input light, while maintaining the FSR unchanged. The proposed comb filter has the potential to be used in optical dense wavelength division multiplexing communication systems.

In this paper, we propose a microdisk resonator with negative thermal optical coefficient (TOC) polymer for refractive index (RI) sensing with thermal stability. The transmission characteristics and sensing performances by using quasi-TE01 and quasi-TM01 modes are simulated by a three-dimensional finite element method. The influences of the TOC, RI, and thickness of the polymer on the sensing performances are also investigated. The simulation results show that the RI sensitivity Sn and temperature sensitivity ST with different polymers are in the ranges of 25.1-26 nm/RIU and 67.3-75.2 pm/K for the quasi-TE01 mode, and 94.5-110.6 nm/RIU and 1.2-51.3 pm/K for the quasi-TM01 mode, respectively. Moreover, figure-of-merit of the temperature sensing for the quasi-TM01 mode is in the range of 2 × 10-4-8 × 10-3, which can find important application in the implementation of the adiabatic devices.

This paper proposes a novel liquid crystal-filled, dual core photonic crystal fiber polarization beam splitter (LC-DC-PCF PBS) based on the coupled mode theory of DC-PCF. The mode birefringence of odd and even modes, coupling lengths (CLs) of the X-polarization (X-pol) and Y-polarization (Y-pol), and the corresponding coupling length ratio (CLR) of the proposed LC-DC-PCF PBS filled without LC E7 and with LC E7 are compared. The change rules of the CLs of the X-pol and Y-pol and CLR of the proposed LC-DC-PCF with wavelengths for different cladding microstructure parameters were investigated. The relationships between the X-pol and Y-pol normalized output powers in core A of the proposed LC-DC-PCF PBS and the propagation length at the wavelength of 1.604 μm are discussed. Finally, by studying the change of extinction ratio (ER) with wavelength, the LC-DC-PCF PBS ER of 60.3 and 72.2 dB at wavelengths 1.386 and 1.619 μm are achieved, respectively. The final splitting length (LS) is 94 μm, and the splitting bandwidth is 349 nm (1.352~1.701 μm), covering the whole of the E + S + C + L + U communication bands. The proposed LC-DC-PCF PBS has good beam-splitting performance, such as ultra-short LS and ultra-wide splitting bandwidth, with potential applications in laser, sensing, and communication systems.

Abstract Deep-ultraviolet (UV) second-harmonics (SHs) have important applications in basic physics and applied sciences. However, it still remains challenging to generate deep-UV SHs especially in optical fibers. Here, for the first time, we experimentally demonstrate the deep-UV SH generations (SHGs) by combined degenerate four-wave mixing (FWM) and surface nonlinearity polarization in an in-house designed and fabricated air-silica photonic crystal fiber (PCF). When femtosecond pump pulses with average input power P av of 650 mW and center wavelength λ p of 810, 820, 830, and 840 nm are coupled into the normal dispersion region close to the zero-dispersion wavelength of the fundamental mode of the PCF, the anti-Stokes waves induced by degenerate FWM process are tunable from 669 to 612 nm. Then, they serve as the secondary pump, and deep-UV SHs are generated within the wavelength range of 334.5 to 306 nm as a result of surface nonlinearity polarization at the core-cladding interface of the PCF. The physical mechanism of the SHGs is confirmed by studying the dependences of the output power P SH of the SHs on the PCF length and time. Finally, we also establish a theoretical model to analyze the SHGs.

Parabolic pulses have important applications in both basic and applied sciences, such as high power optical amplification, optical communications, all-optical signal processing, etc. The generation of parabolic similaritons in tapered hydrogenated amorphous silicon photonic wires at telecom (λ ~ 1550 nm) and mid-IR (λ ≥ 2100 nm) wavelengths is demonstrated and analyzed. The self-similar theory of parabolic pulse generation in passive waveguides with increasing nonlinearity is presented. A generalized nonlinear Schrödinger equation is used to describe the coupled dynamics of optical field in the tapered hydrogenated amorphous silicon photonic wires with either decreasing dispersion or increasing nonlinearity. The impacts of length dependent higher-order effects, linear and nonlinear losses including two-photon absorption, and photon-generated free carriers, on the pulse evolutions are characterized. Numerical simulations show that initial Gaussian pulses will evolve into the parabolic pulses in the waveguide taper designed.

In this paper, a microdisk resonator with two whispering-gallery modes (WGMs) is proposed for label-free biochemical sensing. According to the transmission responses of the two WGMs with different coupling gaps, there is the critical coupling status for the WGM (0, 36) while there is no critical coupling status for the WGM (1, 28). For the WGMs (0, 36) and (1, 28), the refractive index (RI) sensitivities of 45.8821 and 72.9402 nm/RIU are obtained, and the corresponding RI detection limits (DLs) of 8.5902 × 10-4 and 1.9228 × 10-3 RIU are achieved, respectively. Moreover, the proposed sensor also has the temperature sensitivities of 0.0730 and 0.0703 nm/K, which correspond to the temperature DLs of 0.1631 and 0.6263 K, respectively. By constructing a characteristic matrix, it is demonstrated that simultaneous measurement of the RI and temperature can be achieved.

We experimentally demonstrate a single-end photodetector (PD) based polarization-division-multiplexing (PDM) system, in which the single-sideband orthogonal frequency-division multiplexing (SSB-OFDM) and discrete multitone (DMT) signals are modulated on two orthogonal polarizations respectively. Based on the frequency interleave design for dual-polarization, the spectral efficiency and chromatic dispersion tolerance can be optimized. We derive the theoretical model for the PDM-SSB-DMT system and detail the digital signal processing for demultiplexing at the receiver. We also successfully transmit a 50 Gb/s PDM-SSB-DMT signal with 14 GHz bandwidth over 40 km of uncompensated and unamplified standard single mode fiber (SSMF) with only 1.1 dB power penalty for a bit error rate of 3.8 × 10–3 relative to back-to-back transmissions.

In this paper, a novel gold film-coated V-shape dual-core photonic crystal fiber (V-DC-PCF) polarization beam splitter (PBS) based on surface plasmon resonance effect is proposed. The coupling lengths of the X-polarization (X-pol) and Y-polarization (Y-pol) and the corresponding coupling length ratio of the proposed V-DC-PCF PBS without gold film and with gold film are compared. The fiber structure parameters and thickness of the gold film are optimized through investigating their effects on the coupling lengths and coupling length ratio. As the propagation length increases, the normalized output powers of the X-pol and Y-pol of the proposed V-DC-PCF PBS at the three wavelengths 1.610, 1.631, and 1.650 μm are demonstrated. The relationships between the extinction ratio (ER), insertion loss (IL) and wavelength for the three splitting lengths (SLs) 188, 185, and 182 μm are investigated. Finally, it is demonstrated that for the proposed V-DC-PCF PBS, the optimal SL is 188 μm, the ILs of the X-pol and Y-pol are less than 0.22 dB, and the splitting bandwidth (SB) can cover the E + S + C + L + U band. The proposed V-DC-PCF PBS has the ultra-short SL, ultra-wide SB, and ultra-low IL, so it is expected to have important applications in the laser, sensing, and dense wavelength division multiplexing systems.

In this paper, a hollow-core negative curvature fiber (HC-NCF) with high birefringence is proposed for low refractive index (RI) sensing based on surface plasmon resonance effect. In the design, the cladding region of the HC-NCF is composed of only one ring of eight silica tubes, and two of them are selectively filled with the gold wires. The influences of the gold wires-filled HC-NCF structure parameters on the propagation characteristic are investigated by the finite element method. Moreover, the sensing performances in the low RI range of 1.20–1.34 are evaluated by the traditional confinement loss method and novel birefringence analysis method, respectively. The simulation results show that for the confinement loss method, the obtained maximum sensitivity, resolution, and figure of merit of the gold wires-filled HC-NCF-based sensor are −5700 nm/RIU, 2.63 × 10−5 RIU, and 317 RIU−1, respectively. For the birefringence analysis method, the obtained maximum sensitivity, resolution, and birefringence of the gold wires-filled HC-NCF-based sensor are −6100 nm/RIU, 2.56 × 10−5 RIU, and 1.72 × 10−3, respectively. It is believed that the proposed gold wires-filled HC-NCF-based low RI sensor has important applications in the fields of biochemistry and medicine.

The humidity and temperature responses of a microfiber coupler (MFC) coated with silica gel are investigated. Two MFC structures with different waist diameters of 2.5 and 3.5 μm were fabricated by fusing and tapering two single-mode fibers using a microheater brushing technique. The influences of the coating thickness and tapered waist diameter on the sensing performance are analyzed. For the proposed sensor with a waist diameter of 2.5 μm and 8-layers thick coating, the change in the relative humidity (RH) results in an exponential blueshift with a maximum sensitivity of 1.6 nm/% RH in the range from 70 to 86% RH. In response to the temperature change, the sensor's transmission spectrum redshifts in a linear fashion with an average sensitivity of 0.55 nm/°C in the range from 20 to 40 °C. The study is important for the development of the proposed fiber structure as a humidity or temperature sensor.

A simple polarization-multiplexed (PM) discrete multitone (DMT) system with intensity modulation and direct detection (IM-DD) is proposed for short-reach optical communications. Only four photodetectors (PDs) are required at the receiver, and no extra 90° hybrid and balanced detection is necessary. Novel digital signal processing (DSP) algorithms are proposed for state-of-polarization (SOP) estimation and subsequent mixed polarization beat interference (MPBI) elimination. These enable polarization demultiplexing and channel estimation to be implemented by a simple 2 × 2 multiple-input and multiple-output (MIMO) frequency-domain equalizer. The feasibility of the proposed PM-DMT-DD system and the effectiveness of the novel DSP algorithms are investigated via theoretical and simulation studies.

In this paper, we investigate the strong modulation instability (MI) at telecommunication band in a silicon-organic hybrid slot waveguide. The organic material of polymer poly (bis para-toluene sulfonate) of 2, 4-hexadiyne 1, 6 diol (PTS), which has high third-order nonlinear refractive index and very low two-photon absorption, is used to fill the slot of the waveguide. The optical gain can be up to ~3600 m-1 with a low pump peak power of 300 mW. By using Gaussian pulses with width of 10 ps and peak power of 250 mW, deep modulation of the pump is achieved, and the ultrashort pulse trains with the periods of 27 and 24 fs are obtained in the anomalous and normal group-velocity dispersion regions, respectively.

In this paper, a novel silicon-on-insulator (SOI) waveguide with the multi-period vertical grating is proposed to realize broadband parametric wavelength conversion with a quasi-phase matching technique. The grating period in the former part of the SOI waveguide is optimized to enhance the conversion efficiency at designated signal wavelength and the 3-dB bandwidth. When the continuous-wave pump at 1550 nm is used, the conversion efficiency of -14.0 dB at 1750 nm and the 3-dB bandwidth of 387 nm can be obtained. Compared to the constant-width waveguide, the improvements of 26.7 dB and 298 nm are achieved, respectively. The results show that this SOI waveguide is an ideal device for broadband wavelength conversion without dispersion engineering.

A high temperature (up to 950 °C) sensor was proposed and demonstrated based on a micro taper in-line fiber Mach–Zehnder interferometer (MZI) structure. The fiber MZI structure comprises a single mode fiber (SMF) with two micro tapers along its longitudinal direction. An annealing at 1000 °C was applied to the fiber sensor to stabilize the temperature measurement. The experimental results showed that the sensitivity was 0.114 nm/°C and 0.116 nm/°C for the heating and cooling cycles, respectively, and, after two days, the sensor still had a sensitivity of 0.11 nm/°C, showing a good stability of the sensor. A probe-type fiber MZI was designed by cutting the sandwiched SMF, which has good linear temperature responses of 0.113 nm/°C over a large temperature range from 89 to 950 °C. The probe-type fiber MZI temperature sensor was independent to the surrounding refractive index (RI) and immune to strain. The developed sensor has a wide application prospect in the fields of high temperature hot gas flow, as well as oil and gas field development.

The bending response of polymer optical fibre Bragg grating (POFBG) and silica optical fibre Bragg grating (SOFBG) mounted on a brass beam have been systematically studied and compared. The results indicate that POFBG has higher (almost twice as much) bend sensitivity than SOFBG. Based on the difference between the bend and temperature sensitivity of POFBG and SOFBG, a new method of measuring vector bend and temperature simultaneously was proposed by using a hybrid sensor head with series connection of one POFBG and one SOFBG with different Bragg wavelengths. It provides high sensitivity and resolution for sensing bend and temperature changes simultaneously and independently. The proposed sensor can find some applications in the fields where high sensitivity for both bend and temperature measurements are required.

In existing anomaly detection approaches, sensor node often turns to neighbors to further determine whether the data is normal while the node itself cannot decide. However, previous works consider neighbors' opinions being just normal and anomalous, and do not consider the uncertainty of neighbors to the data of the node. In this paper, we propose SLAD (subjective logic based anomaly detection) framework. It redefines opinion deriving from subjective logic theory which takes the uncertainty into account. Furthermore, it fuses the opinions of neighbors to get the quantitative anomaly score of the data. Simulation results show that SLAD framework improves the performance of anomaly detection compared with previous works.

In this paper, we propose a novel lumped time-delay compensation scheme for the all-optical analog-to-digital conversion based on soliton self-frequency shift and optical interconnection techniques. By inserting a segment of negative dispersion fiber between the quantization and the coding module, the time delay of different quantized pulses can be accurately compensated with a simple structure compared to the multiple time-delay lines. The simulation results show that the coding pulses can be well synchronized using a span of fiber, with the flattened negative dispersion within the wavelength range of 1558-1620 nm. In addition, the problems of pulse broadening and time error are discussed, and it is shown that no damage happens to the coding correctness within the sampling rate of 30 GSa/s.