[Show abstract][Hide abstract] ABSTRACT: Interrogating an object with a light beam and analyzing the scattered light can reveal kinematic information about the object, which is vital for applications ranging from autonomous vehicles to gesture recognition and virtual reality. We show that by analyzing the change in the orbital angular momentum (OAM) of a tilted light beam eclipsed by a moving object, lateral motion of the object can be detected in an arbitrary direction using a single light beam and without object image reconstruction. We observe OAM spectral asymmetry that corresponds to the lateral motion direction along an arbitrary axis perpendicular to the plane containing the light beam and OAM measurement axes. These findings extend OAM-based remote sensing to detection of non-rotational qualities of objects and may also have extensions to other electromagnetic wave regimes, including radio and sound.
[Show abstract][Hide abstract] ABSTRACT: Recently there is a growing interest in developing few-mode fiber (FMF) based distributed sensors, which can attain higher spatial resolution and sensitivity compared with the conventional single-mode approaches. However, current techniques require two lightwaves injected into both ends of FMF, resulting in their complicated setup and high cost, which causes a big issue for geotechnical and petroleum applications. In this paper, we present a single-end FMF-based distributed sensing system that allows simultaneous temperature and strain measurement by Brillouin optical time-domain reflectometry (BOTDR) and heterodyne detection. Theoretical analysis and experimental assessment of multi-parameter discriminative measurement techniques applied to distributed FMF sensors are presented. Experimental results confirm that FM-BOTDR has similar performance with two-end methods such as FM-BOTDA, but with simpler setup and lower cost. The temperature-induced expansion strain (TIES) in response to different modes is discussed as well. Furthermore, we optimized the FMF design by exploiting modal profile and doping concentration, which indicates up to fivefold enhancement in measurement accuracy. This novel distributed FM-sensing system endows with good sensitivity characteristics and can prevent catastrophic failure in many applications.
[Show abstract][Hide abstract] ABSTRACT: Given the introduction of coherent 100G systems has provided enough fiber capacity to meet data traffic growth in the near term, enhancing network efficiency will be service providers' high priority. Adding flexibility at the optical layer is a key step to increasing network efficiency, and both spectral and spatial functionality will be considered in next generation optical networks along with advanced network management to effectively harness the new capabilities.
[Show abstract][Hide abstract] ABSTRACT: A multinary-signaling-based coded-modulation (CM) scheme is proposed, which is suitable for various applications ranging from multi-Tb/s to multi-Pb/s data rates, outperforming conventional CM schemes in terms of both spectral and energy efficiencies. The corresponding multinary signal constellation design algorithm is also proposed. Both 2-D and 3-D multinary-signaling-based CM schemes have been studied.
[Show abstract][Hide abstract] ABSTRACT: An optimized vector-quantization-inspired signal constellation design (OVQ-SCD) suitable for multidimensional optical transport is proposed, in which signal constellation radii transformation function is optimized and near-uniform distribution of points is achieved. The proposed OVQ-SCD is used in a tandem with a hybrid multidimensional coded-modulation scheme employing Slepian sequences as electrical discrete-time basis functions, orthogonal prolate spheroidal wave functions as impulse responses of optical filters in orthogonal-division multiplexing, and spatial modes as optical continuous-time basis functions. It has been shown that the proposed multidimensional coded-modulation schemes based on OVQ-SCDs outperform corresponding counterparts and can be used to enable beyond 10 Pb/s serial optical transport over spatial division multiplexing (SDM) fibers as well as beyond 1 Pb/s transport over SMFs. The proposed OVQ-SCD-based hybrid multidimensional coded modulation scheme can simultaneously solve the problems related to the limited bandwidth of information-infrastructure, high energy consumption, and heterogeneity of network segments; while enabling elastic and dynamic bandwidth allocation.
[Show abstract][Hide abstract] ABSTRACT: We demonstrate the first SDN-controlled optical topology-reconfigurable mobile fronthaul (MFH) architecture for bidirectional coordinated multipoint (CoMP) and low latency inter-cell device-to-device (D2D) connectivity in the 5G mobile networking era. SDN-based OpenFlow control is used to dynamically instantiate the CoMP and inter-cell D2D features as match/action combinations in control plane flow tables of software-defined optical and electrical switching elements. Dynamic re-configurability is thereby introduced into the optical MFH topology, while maintaining back-compatibility with legacy fiber deployments. 10Gb/s peak rates with <7μs back-to-back transmission latency and 29.6dB total power budget are experimentally demonstrated, confirming the attractiveness of the new approach for optical MFH of future 5G mobile systems.
[Show abstract][Hide abstract] ABSTRACT: A class of generalized low-density parity-check (GLDPC) codes suitable for optical communications is proposed, which consists of multiple local codes. It is shown that Hamming, BCH, and Reed-Muller codes can be used as local codes, and that the maximum a posteriori probability (MAP) decoding of these local codes by Ashikhmin-Lytsin algorithm is feasible in terms of complexity and performance. We demonstrate that record coding gains can be obtained from properly designed GLDPC codes, derived from multiple component codes. We then show that several recently proposed classes of LDPC codes such as convolutional and spatially-coupled codes can be described using the concept of GLDPC coding, which indicates that the GLDPC coding can be used as a unified platform for advanced FEC enabling ultra-high speed optical transport. The proposed class of GLDPC codes is also suitable for code-rate adaption, to adjust the error correction strength depending on the optical channel conditions.
[Show abstract][Hide abstract] ABSTRACT: A class of GLDPC-codes is proposed consisting of multiple local-codes suitable for code-rate-adaptation in high-speed optical-transport-networks, providing excellent coding-gains. GLDPC-decoder for proposed codes is more suitable for parallelization in FPGA/ASIC-hardware compared to LDPC-decoder.
[Show abstract][Hide abstract] ABSTRACT: Centralized detection in a network of Chirped Laser Dispersion Spectroscopy (CLaDS) sensors requires efficient signal processing. The optimization of CLaDS processing and development of a custom digital signal processing unit in place of restricting conventional bench-top instruments is discussed.
[Show abstract][Hide abstract] ABSTRACT: An optimized-vector-quantization-based signal-constellation-design (OVQ-SCD) suitable for beyond 1Pb/s serial multidimensional-optical-transport is proposed, in which signal-constellation-radii-transformation-function is optimized and near-uniform-distribution of points is achieved.
[Show abstract][Hide abstract] ABSTRACT: In this paper, we first describe an optimal signal constellation design algorithm suitable for the coherent optical channels dominated by the linear phase noise. Then, we modify this algorithm to be suitable for the nonlinear phase noise dominated channels. In optimization procedure, the proposed algorithm uses the cumulative log-likelihood function instead of the Euclidian distance. Further, an LDPC coded modulation scheme is proposed to be used in combination with signal constellations obtained by proposed algorithm. Monte Carlo simulations indicate that the LDPC-coded modulation schemes employing the new constellation sets, obtained by our new signal constellation design algorithm, outperform corresponding QAM constellations significantly in terms of transmission distance and have better nonlinearity tolerance. (c) 2015 Optical Society of America
[Show abstract][Hide abstract] ABSTRACT: In this paper, we propose and experimentally verify a low-latency digital signal processing (DSP)-free synchronous clock distribution and recovery scheme for high-speed dense wavelength division multiplexing orthogonal frequency division multiple access (DWDM-OFDMA)-based mobile backhaul (MBH) systems. The synchronous clock distribution is achieved jointly with high-speed OFDMA data signal transmission through a simple and low-cost intensity-modulation direct-detection (IMDD) optical backhaul architecture that also guarantees clock time and frequency stability. We experimentally verify aggregate 41.09-Gb/s (7λ × 5.87 Gb/s/λ) DWDM-OFDMA data rates with distribution and recovery of 50-MHz square wave and 4-GHz sinusoid clocks over 40 km standard single mode fiber (SSMF) with spectrally-efficient 25-GHz channel spacing and no remote optical amplification. To demonstrate the flexibility of the proposed system, aggregate 51.31-Gb/s (7λ × 7.33 Gb/s/λ) DWDM-OFDMA transmission with 50-MHz square wave and 5-GHz sine wave clocks is also experimentally evaluated. Highly precise time and frequency accuracy is achieved, featuring an order of magnitude improvement with respect to LTE-Advanced (LTE-A) synchronization requirements. By supporting high bit rates, high spectral efficiency, and low-latency synchronization, the proposed approach is promising for future optical MBH.
[Show abstract][Hide abstract] ABSTRACT: We propose and experimentally verify novel low-complexity clock distribution and recovery for high-speed UDWDM-OFDMA-based mobile backhaul using SSB modulation and envelope detection. 30Gb/s UDWDM-OFDMA transmission with synchronous 50MHz clock distribution over 40km SSMF is achieved.
[Show abstract][Hide abstract] ABSTRACT: We experimentally demonstrate the first OpenFlow-enabled transport SDN that performs multi-flow switching by cross-layer optimization and configuring all major hardware elements, including adaptive EDFA-Raman amplifier, multi-degree superchannel transponder, and flexible grid switching node.
[Show abstract][Hide abstract] ABSTRACT: 400-Gb/s dual-carrier DP-8QAM transmission over 6,787 km is reported at 121.2km span length, the longest to date with EDFA only. Spectral efficiency of 4.54 b/s/Hz is achieved thanks to Nyquist shaping and nonlinear compensation techniques.
[Show abstract][Hide abstract] ABSTRACT: We present the first experimental verification of nonlinear Raman crosstalk mitigation via PSD control of 10 Gb/s OOK using simple RF filtering. Beyond 5dB crosstalk suppression is achieved without bandwidth expansion after 25-km SSMF transmission.
[Show abstract][Hide abstract] ABSTRACT: We introduce architectures to enable flexible-client functionality in software-defined transport networks for the first time, and propose an effective algorithm to provision time-varying traffic. Transponders with flexible-client interfaces improve spectral, energy, and management efficiencies.
[Show abstract][Hide abstract] ABSTRACT: We propose joint bandwidth provisioning and base station caching for video delivery in software-defined PON. Performance evaluation via custom simulation models reveals 30% increase in served video requests and 90% reduction in service response delays.
[Show abstract][Hide abstract] ABSTRACT: We present the first experimental time- and frequency-domain MIMO channel matrix characterization versus distance for 6×28Gbaud recirculating loop transmission over 40×25km FMF. Beyond 10dB time- and frequency-domain singular-value spreads are observed, motivating nonlinear MIMO equalization.