L. Poti

Ultrafast integrable and reconfigurable XNOR, AND, NOR, and NOT photonic logic gate

A novel, simple, compact, and integrable scheme of reconfigurable and ultrafast photonic logic gate is demonstrated, based on a single semiconductor optical amplifier (SOA) and able to process ultrafast signals. XNOR function has been optically implemented exploiting four-wave mixing and cross-gain modulation in an SOA. The same scheme can be easily reconfigured to obtain AND, NOR, and NOT logic gates. Performances in terms of bit error rate for 20-ps return-to-zero signals at 10 Gb/s show a power penalty limited to 0.5 dB for all logic gates but the AND, which experiences regeneration (-2-dB power penalty) due to nonlinear SOA noise compression.

Push-Pull Defragmentation Without Traffic Disruption in Flexible Grid Optical Networks

In flexi-grid optical networks, fragmentation of spectrum resources may significantly affect the overall network efficiency. Effective techniques for defragmentation (i.e., re-optimization) are then required to limit the wasting of spectrum resources. However, current defragmentation techniques can only be implemented thanks to the presence of additional resources, such as spare expensive transponders. In this study, we propose, discuss and evaluate a novel defragmentation technique called push-pull. The technique is based on dynamic lightpath frequency retuning upon proper reconfiguration of allocated spectrum resources. It does not require additional transponders and does not determine traffic disruption. All the relevant technological limitations that may affect the push-pull applicability are discussed in the context of both optically-amplified direct and coherent detection systems. The technique is then successfully demonstrated in two different flexi-grid network testbeds, reproducing the two aforementioned scenarios. In particular, the reoptimization of a 10 Gb/s OOK lightpath is safely completed in few seconds (mainly due just to node configuration latencies) without experiencing any traffic disruption. Similarly, the push-pull is successfully performed on a 100 Gb/s PM-QPSK lightpath, providing no traffic disruption.

Photonic Processing for Digital Comparison and Full Addition Based on Semiconductor Optical Amplifiers

An N bit all-optical comparator and an all-optical full adder are presented. These complex circuits, which perform photonic digital processing, are implemented cascading a unique basic gate that exploits cross gain modulation and cross-polarization rotation in a single semiconductor optical amplifier (SOA). Since the interacting signals are counterpropagating in the SOA, they can be set at the same wavelength. Photonic processing improves the speed of the optical networks by reducing the packet latency time to the time-of-flight in the nodes. Digital comparison and full-addition are key functionalities for the processing of the packet labels. Integrated realizations are crucial, thus, SOAs represent a suitable mean both because they allow hybrid integrated solutions and fast operation speed. The performances of the basic gate, the comparator, and the full adder are investigated both in terms of bit error rate and eye opening. To the best of our knowledge this is the first time it is reported on the implementation of an all-optical comparator able to compare patterns longer than 1 bit. Previous works demonstrate the comparison of 1 bit patterns. Only few works report on an all-optical full adder implementation, but with different schemes. In our implementation, sum and carry out do not depend directly on the carry in, thus potentially improving the output signal quality when cascading multiple full adders.

Polarization and wavelength-independent time-division demultiplexing based on copolarized-pumps FWM in an SOA

A novel optical time-division demultiplexer based on copolarized-pumps four-wave mixing in semiconductor optical amplifiers is presented. The scheme is polarization and wavelength independent. Effective 10-Gb/s channel extraction from an optical time-division multiplexed 40-Gb/s aggregate frame is experimentally demonstrated.

Demonstration of data and control plane for optical multicast at 100 and 200 Gb/s with and without frequency conversion

Emerging services, such as high-definition Internet Protocol TV (IP-TV) or data center migration, are going to increase the amount of multicast traffic in the Internet. The support of multicast directly in the optical domain, instead of at the IP layer, is a target for reducing the amount of optical-electronic-optical conversions (thus, the network operational and capital expenditure) and energy consumption. In parallel, flex-grid technology (e.g., bandwidth variable wavelength selective switches) is emerging as a candidate solution to be adopted in future optical transport networks given its capacity of improving spectrum efficiency. This paper is focused on optical multicast inflex-grid optical networks and onits control through the Path Computation Element (PCE). First, we present two node architectures supporting optical multicast. The first node architecture achieves optical multicast through passive light split and requires that the multicast connection satisfies the spectrum continuity constraint. The second node architecture achieves optical multicast with frequency conversion. In particular, a specific implementation of the second architecture is proposed in this paper exploiting a periodically poled lithium niobate (PPLN) waveguide. Then, a PCE architecture to control optical multicast (with and without frequency conversion) is proposed. Optical multicasting, based on the proposed node architectures, at 100 and 200 Gb/s is experimentally demonstrated in a flex-grid network testbed. In particular, multicasting is demonstrated with 112 Gb/s polarization multiplexing 16 quadrature amplitude modulation (PM-16QAM) and polarization multiplexing quadrature phase shift keying (PM-QPSK), and with 224 Gb/s PM-16QAM considering the light-split node architecture. Moreover, optical multicast with two frequency conversions, achieved in a single PPLN device, is demonstrated for the first time with a 224 Gb/s PM-16QAM signal. The testbed also includes the PCE, which is extended to control optical multicast in flex-grid optical networks.

Optical Cross Connects Architecture with per-Node Add&Drop Functionality

We propose a cost-effective implementation of reconfigurable add&drop functionality in Optical Cross Connects based on the concept of common add&drop in the node (OXC with per- Node Add&Drop, OXC-NAD). The proposed architecture constrains usable transponders wavelengths, but the analysis on significant mesh topologies demonstrates that this does not affect the behavior of the transparent networks. The OXC-NAD is shown to also significantly reduce the node cost irrespective of the nodal degree.

Ultrafast all-optical ADD-DROP multiplexer based on 1-m-long bismuth oxide-based highly nonlinear fiber

An all-optical ADD- DROP multiplexer able to carry out ultrafast channel extraction, clearing, and insertion operations for time-interleaved optical signals is presented. The proposed ADD-DROP multiplexer exploits polarization rotation induced by cross-phase modulation in 1-m-long highly nonlinear bismuth oxide-based optical fiber with a nonlinear coefficient of 1250 W/sup -1/ /spl middot/ km/sup -1/. Penalties lower than 1.5 dB in a 4 /spl times/ 10 Gb/s optical-time-division-multiplexed system have been measured for all operations.

Phase noise cancellation in coherent optical receivers by digital coherence enhancement

A novel technique to cancel laser phase noise in coherent receivers is proposed. The equivalent laser linewidth is reduced by a factor of 10, and coherent detection of DQPSK signals affected by strong phase noise is experimentally demonstrated.

First demonstration of SDN-controlled SBVT based on multi-wavelength source with programmable and asymmetric channel spacing

We propose an SBVT based on programmable multi-wavelength source with asymmetric channel spacing. SBVT, controlled by extended SDN, supporting 480 Gb/s super-channel and up to three sliceable optical flows is demonstrated in a network testbed.

Simultaneous Dual-Wavelength Conversion With Multiresonant Saturable Absorption Vertical-Cavity Semiconductor Gate

We experimentally demonstrate the use of a multiresonant, all-optical vertical-cavity semiconductor gate for simultaneously converting the wavelength of an optical data signal into two signals with different wavelengths. The operation of the gate is based on saturable absorption effect in multiple quantum-well structures. The repetition rate of the converted signal is limited by the recovery time of the saturable absorber. The device is compact, passive, polarization-independent, and enables wavelength conversion with a high extinction ratio of more than 10 dB and maximum optical signal-to-noise ratio penalty lower than 3 dB.