Raquel Clavero

IST-LASAGNE: towards all-optical label swapping employing optical logic gates and optical flip-flops

The Information Society Technologies-all-optical LAbel SwApping employing optical logic Gates in NEtwork nodes (IST-LASAGNE) project aims at designing and implementing the first, modular, scalable, and truly all-optical photonic router capable of operating at 40 Gb/s. The results of the first project year are presented in this paper, with emphasis on the implementation of network node functionalities employing optical logic gates and optical flip-flops, as well as the definition of the network architecture and migration scenarios.

All-optical flip-flop based on a single SOA-MZI

A novel architecture of an all-optical flip-flop is proposed. The architecture is comprised of a single semiconductor optical amplifier-based Mach-Zehnder interferometer with a feedback loop. The simulation results show that low switching energies (<2-pJ pulses) and fast operation (<1-ns response delays) may be achieved.

All-optical flip-flop based on an active Mach-Zehnder interferometer with a feedback loop.

A novel architecture for an all-optical flip-flop is validated experimentally. The architecture comprises a single semiconductor optical amplifier-based Mach-Zehnder interferometer with an external feedback loop. The experimental results show optical bistable operation for a latching device with an on-off contrast ratio of 11 dB that employs set and reset pulses of less than 250 pJ, although the energy of these pulses could be greatly reduced by optical integration of the whole device.

All-Optical Processing Based on a Logic xor Gate and a Flip-Flop Memory for Packet-Switched Networks

The routing functionality by all-optically interconnecting semiconductor-based all-optical logic gates and flip-flops is demonstrated in the frame of an all-optical label swapping (AOLS) network. We experimentally show that the output of the all-optical 2-bit correlator is capable of toggling the states of the integrated flip-flop every 2.5 ns via an adaptation stage. High extinction ratios are obtained at the output of the flip-flop, which can be used to feed a high-speed wavelength converter to complete the routing functionality of the AOLS node. The potential integration of these semiconductor optical amplifier integrated Mach-Zehnder interferometer-based devices make the proposed approach a very interesting solution for future packet switched optical networks.

Bistability Analysis for Optical Flip-Flops Based on a SOA-MZI With Feedback

Theoretical models that are used to describe the stable output states in optical flip-flop configurations based on a single semiconductor-optical-amplifier-based Mach-Zehnder interferometer with feedback are derived. The calculated flip-flop states, as well as optical bistability curves, allow for an accurate characterization of the flip-flop operation during the design phase prior to experiments, showing that the system parameters must be carefully chosen to obtain correct operation. Furthermore, dynamic effects such as switching time and pulse-energy requirements are also obtained as a function of the length of the feedback loop.

Linear and nonlinear crosstalk evaluation in DWDM networks using optical Fourier transformers

A novel DWDM channel monitoring technique based on the conversion from wavelength domain to time domain by performing a real-time optical Fourier transform over the whole DWDM system bandwidth is proposed and experimentally demonstrated. The use of chromatic dispersion-based optical Fourier transformers has been validated in the case of a spectrum comprising light from different uncorrelated sources. Linear and nonlinear crosstalks between the DWDM channels appear as amplitude noise at specific time positions. The correspondence of this amplitude noise with the crosstalk spectral distribution is evaluated theoretically and experimentally.

Performance analysis of polarimetric PMD monitoring by real-time optical Fourier transformers

A spectral polarimeter based on the real-time optical Fourier transform of one or some consecutive Gaussian pulses extracted from an optical transmission link is proposed and its operational limits evaluated. Polarization-mode dispersion (PMD) is calculated from the state-of-polarization spectral rotation rate with 0.36-GHz spectral resolution. The experimental results show sucessful PMD measurement inside 1.9-ps Gaussian return-to-zero pulses in good agreement with the theoretical calculations

PMD monitoring by spectral SOP rotation using a real-time optical Fourier transformer

Experimental demonstration of a non-invasive spectral polarimeter (SOP spectral evolution monitored in 1.9 ps Gaussian-RZ pulses). DGD is derived from SOP spectral rotation rate. Real-time optical Fourier transform is used to map SOP traces from spectrum-to-time.

Orthogonal wavelength-division-multiplexing technique feasibility evaluation

A novel high-spectral-efficiency modulation scheme using square time pulses in orthogonal wavelength-division multiplexing is proposed. Experimental results demonstrate the significant reduction of the interchannel linear crosstalk-induced penalty compared with Gaussian return-to-zero (RZ) modulation. The proposed technique allows a maximum spectral efficiency of 1 b/s/Hz. Simulation studies and experimental work confirming the expected performance are presented.

All-Optical Self-Routing Packet Switch Based on Active Mach-Zehnder Interferometer Latching Circuit

A new architecture for an all-optical self-routing packet switch is reported. The experimental results at 40 Gbit/s show a low power penalty and a contrast ratio around 9 dB.