Philip N. Ji

1.05Pb/s Transmission with 109b/s/Hz Spectral Efficiency using Hybrid Single- and Few-Mode Cores

We demonstrated 1.05-Pb/s transmission over 3km of multicore fiber with spectral efficiency of 109b/s/Hz, using twelve single-mode cores carrying DP-32QAM-OFDM signals and two few-mode cores carrying DP-QPSK in their LP01 and two LP11 modes.

10-Gb/s OFDMA-PON for Delivery of Heterogeneous Services

We propose a novel method to generate transparent pipes for transmission of heterogeneous services over 10-Gb/s OFDMA-PON architecture. We successfully demonstrated the simultaneous transmission of two PON channels combined with a standard WiMAX channel.

SDN and OpenFlow for Dynamic Flex-Grid Optical Access and Aggregation Networks

We propose and discuss the extension of software-defined networking (SDN) and OpenFlow principles to optical access/aggregation networks for dynamic flex-grid wavelength circuit creation. The first experimental demonstration of an OpenFlow1.0-based flex-grid λ-flow architecture for dynamic 150 Mb/s per-cell 4 G Orthogonal Frequency Division Multiple Access (OFDMA) mobile backhaul (MBH) overlays onto 10 Gb/s passive optical networks (PON) without optical network unit (ONU)-side optical filtering, amplification, or coherent detection, over 20 km standard single mode fiber (SSMF) with a 1:64 passive split is also detailed. The proposed approach can be attractive for monetizing optical access/aggregation networks via on-demand support for high-speed, low latency, high quality of service (QoS) applications over legacy fiber infrastructure.

Routing, wavelength assignment, and spectrum allocation algorithms in transparent flexible optical WDM networks

Abstract Current fixed grid wavelength routed networks are limited in terms of spectral efficiency due to the rigid nature of wavelength assignment. We propose the Flexible Optical WDM (FWDM) network architecture for flexible grid optical networks in which the constraint on fixed spectrum allocation to channels is removed and network resources can be dynamically provisioned with an automated control plane. In this paper, we address the routing, wavelength assignment, and spectrum allocation problem (RWSA) in transparent FWDM networks with the objective of maximizing spectral efficiency. We formulate the RWSA problem using an Integer Linear Program (ILP). We also prove the NP-completeness of the RWSA problem, and propose three efficient polynomial time algorithms; namely the Greedy-Routing, Wavelength Assignment, and Spectrum Allocation algorithm (Greedy-RWSA); the K -Alternate Paths Routing, Wavelength Assignment, and Spectrum Allocation algorithm (KPaths-RWSA); the Shortest Path Routing, Wavelength Assignment, and Spectrum Allocation algorithm (SP-RWSA). We analyze the lower bound on the required spectrum for the given network topology and a set of requests. Simulation results demonstrate that FWDM networks are efficient in terms of spectrum, cost, and energy compared to fixed grid networks. The performance of the proposed algorithms is very close to the lower bound, and approaches to the lower bound as problem size increases.

Terabit/s Nyquist Superchannels in High Capacity Fiber Field Trials Using DP-16QAM and DP-8QAM Modulation Formats

We report the results of two field trials aimed at achieving high fiber capacity over regional and long-haul distances. In the first trial, 41 superchannels with digital Nyquist pulse-shaping were generated and tightly packed to fill up both C-band and L-band. Each subcarrier was modulated with 24.8-Gbaud dual-polarization 16 quadrature amplitude modulation (DP-16QAM) data. The signal carrying net 54.2 Tb/s data was transmitted over 634 km of dispersion uncompensated field-installed standard single mode fiber with the aid of hybrid EDFA and Raman amplification and digital coherent detection. In the second trial for long-haul distances, we extended the transmission distance over 1,822 km. This increase in reach was achieved by reducing the net total capacity to 40.5 Tb/s and modulating the signals with dual-polarization 8 quadrature amplitude modulation (DP-8QAM) Nyquist carrier modulation. A novel rate-adaptive low-density parity-check coding was employed, so that the transmitted channels can exhibit different code rates, adapted by the concatenation of hard-decision and soft-decision forward error correcting codes for enhancing error-correction capability. To the best of our knowledge, we achieved the highest field trial capacity to date at 54.2 Tb/s in regional distances. Furthermore, in long-haul applications, the reported capacity × distance product of 73.79 Pb/s·km is the highest to date.

Software defined optical network

Software define network, which has good potential for packet-switched IP network, is currently not available on circuit-switched transport network. This paper introduces the concept of software define optical network that applies SDN-like features to optical transport network, and reviews key enabling technologies at various layers, such as variable transponder, flexible switching node, control applications, and open interface with circuit extension.

Design and Evaluation of a Flexible-Bandwidth OFDM-Based Intra-Data Center Interconnect

Data center networks are facing growing challenges to deliver higher bandwidth efficiency, lower latency, better flexibility, and lower cost. Various optical interconnect schemes have been proposed to take advantage of the high bandwidth capacity and low power consumption offered by optical switching. However, these schemes cannot offer flexible bandwidth sharing due to the large granularity in optical circuit switching, and they require costly optical components. In this paper, we introduce a novel data center network architecture based on cyclic arrayed waveguide grating device and multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing technology with parallel signal detection (PSD). This architecture offers flexible bandwidth resource sharing at fine granularity. Other features include high-speed switching, low and uniform latency, and the ability to change the data rates dynamically. By eliminating costly optical components and keeping the core optical router passive and static, the power consumption, hardware cost, and operation cost are reduced. The fine granularity bandwidth sharing and MIMO switching through PSD are verified experimentally. We also propose and evaluate efficient subcarrier allocation schemes to achieve high bandwidth utilization. Finally, we present the implementation of an efficient scheduler for the bandwidth allocation of the proposed scheme.

PONIARD: A Programmable Optical Networking Infrastructure for Advanced Research and Development of Future Internet

Motivated by the design goals of Global Environment for Network Innovation (GENI), we consider how to support the slicing of link bandwidth resources as well as the virtualization of optical access networks and optical backbone mesh networks. Specifically, in this paper, we study a novel programmable mechanism called optical orthogonal frequency division multiplexing (OFDM)/orthogonal frequency division multiple access (OFDMA) for link virtualization. Unlike conventional time division multiplexing (TDM)/time division multiple access (TDMA) and wavelength division multiplexing (WDM)/wavelength division multiple access (WDMA) methods, optical OFDM/OFDMA utilizes advanced digital signal processing (DSP), parallel signal detection (PSD), and flexible resource management schemes for subwavelength level multiplexing and grooming. Simulations as well as experiments are conducted to demonstrate performance improvements and system benefits including cost-reduction and service transparency.

Colorless and directionless multi-degree reconfigurable optical add/drop multiplexers

The reconfigurable optical add/drop multiplexer (ROADM) has become one of the most important elements in the DWDM network. The next generation multi-degree ROADM requires two main features: colorless and directionless. Colorless means that add/drop ports are not wavelength specific, and directionless feature enables any transponder to be connected to any degree. In this paper we review and analyze different multi-degree ROADM node architectures that offer full colorless and directionless features. Their key characteristics and properties, including optical loss, size, cost, modularity and upgradability, are compared and discussed.

400Gb/s (4 × 100Gb/s) orthogonal PDM-RZ-QPSK DWDM Signal Transmission over 1040km SMF-28

We have generated 4 x 100-Gb/s orthogonal WDM optical signal by employing polarization-division-multiplexed (PDM) return-to-zero (RZ) QPSK modulation format and tight optical filtering technique. The required optical signal-to-noise ratio (OSNR) at bit error ratio (BER) of 2 x 10(-3) for the 400 Gb/s orthogonal DWDM signal is measured to be approximately 22.8 dB/0.1 nm. After transmission over 1040-km standard single mode fiber (EDFA-only amplification, 80-km amplifier span and fully receiver-side electrical dispersion compensation), the measured BER for all the four orthogonal subchannels are smaller than 2 x 10(-3).