J. B. Rosas-Fernandez

Single SOA based 16 DWDM channels all-optical NRZ-to-RZ format conversions with different duty cycles

We demonstrate simultaneous NRZ-to-RZ conversion for 16 DWDM channels, using a single SOA and a subsequent delay interferometer (DI) acting as a comb-like filter to control the obtained pulse-width for all of the channels. The SOA is operated in deep saturation, resulting in weak cross gain modulation and cross phase modulation induced crosstalk between different NRZ channels. By adjusting the detuning between the peaks in the DI spectrum and each corresponding carrier, good quality RZ signals with different duty cycles can be achieved. Bit-error-rate measurements show negative power penalties for the obtained RZ signals with different duty cycles. Significant timing jitter reductions for all channels show the good regenerative performance of the proposed converter.

Label Stacking in Photonic Packet-Switched Networks With Spectral Amplitude Code Labels

Label stacking is used for hierarchical addressing to reduce the size of lookup tables and to increase the speed of the routing process. We propose an optical label stacking using spectral-amplitude codes (SAC) as labels to accomplish ultrafast packet forwarding. We discuss the advantages of this label architecture compared to other proposals in the literature and present experimental results. We experimentally examine two types of optical packets, one with separable SAC labels and the other one with SAC-encoded payloads. In the first case, the SAC label is a collection of spectral tones modulated at the packet rate (low rate), and the payload is on a separate wavelength modulated at the data rate (fast rate). In the second case, the payload data modulates the collection of wavelengths that constitute the code. We implement a network with two forwarding nodes, and we transmit the packets with two labels in the label stack over 80 km of fiber and measure the bit error rate (BER) after two hops. We achieve error-free transmission (BER<10 -9) for the packets with SAC labels and SAC-encoded payload at payload bit rates of 10 and 2.5 Gb/s, respectively. This is the first experimental demonstration of optical label stacking to our knowledge

Simultaneous multiple DWDM channel NRZ-to-RZ regenerative format conversion at 10 and 20 Gb/s

We propose and demonstrate simultaneous optoelectronic NRZ-to-RZ regenerative format conversion for multiple DWDM channels using a single phase modulator (PM) and a fibre delay-interferometer (DI). In order to accommodate multiple DWDM channels, the DI is designed to have a free spectral range (FSR) equal to the channel spacing. This thus extracts the chirp induced by the phase modulation for all the channels at the same time. Since the original carriers are suppressed to some extent, the NRZ-to-RZ conversions can be achieved with regeneration. Multi-channel format conversion is successfully demonstrated for 16 channels at 10 Gb/s and 8 channels at 20 Gb/s, with a channel spacing of 100 GHz. Bit error ratio (BER) measurements at 10 Gb/s show 3.5 and 4.2 dB penalty improvements for 50 and 75 km transmission without dispersion compensation, respectively. Significant extinction ratio (ER) improvement and timing jitter reduction is observed for the converted channels.

Ultrafast Forwarding Architecture Using a Single Optical Processor for Multiple SAC-Label Recognition Based on FWM

We propose and demonstrate a novel ultrafast label processor that can recognize multiple spectral amplitude coded (SAC) labels using four wave mixing (FWM) sideband allocation and selective optical filtering. Our proposed solution favors hardware simplicity over bandwidth efficiency in order to achieve ultra- fast label recognition at reasonable cost. Our implementation, unlike all other optical label processing techniques, does not require time gating, envelope detectors, or serial-to-parallel converters. Labels are transmitted simultaneously with the payload, improving temporal efficiency at the expense of spectral efficiency. Note that bandwidth efficiency can be improved through a frequency management scheme that uses irregular spacing of wavelengths for payload and label, a complexity overhead in management similar to that in long-haul networks employing irregular spacing of carriers to avoid FWM products. We present two experiments of the single processor for ultrafast forwarding using first optoelectronic and then all-optical switches. In the first experiment, we use 10 SAC labels with minimum bin separation of 25 GHz, 10 Gb/s variable-length data packets, and forward packets over 200 km using electrooptical switches. In the second experiment, all-optical switching at 40 Gb/s is demonstrated using a SAC family for up to 36 labels. We present details on the families of spectral codes for label recognition, using unequally spaced frequency bins. A code family with weight 2 and length 9 uniquely identifies 36 labels. Hardware complexity is moderate compared with short-pulse code labels (mode-locked laser) techniques. Two stable tunable lasers are required for label generation of this code family; all other hardware is commercial, off-the-shelf components such as semiconductor optical amplifiers, array waveguide gratings, optoelectronic switches, and photodetectors.

Low-cost, Scalable Optical Packet Switching Networks with Multi-Wavelength Labels

We propose a self-forwarding packet-switched optical network with bit-parallel multi-wavelength labels. We experimentally demonstrate transmission of variable-length optical packets over 80 km of fiber and switching over a 1x4 multistage switch with two stages.

A Single All-Optical Processor for Multiple Spectral Amplitude Code Label Recognition Using Four Wave Mixing

We propose a novel label processor which can recognize multiple spectral-amplitude-code labels using four-wave-mixing sidebands and selective optical filtering. Ten code-labels × 10 Gbps variable-length packets are transmitted over a 200 km single-hop switched network.

Label stacking using spectral amplitude code labels for optical packet switching

We demonstrate experimentally for the first time successful forwarding of packets using spectral-amplitude-code labels and label stacking in a two-hop network. Optical code-label stacking can be used for hierarchical routing, virtual-private networks and path protection

Optical Packet Switching Networks With Binary Multiwavelength Labels

We propose a network structure for routing optical packets based on binary multiwavelength labels. We resolve the main drawbacks of previously proposed optical label switching scenarios: high splitting loss and complex, expensive hardware. In our scheme, the label is mapped bit-by-bit to a selection of wavelength bins. Variable-length packets are self-forwarded via a multistage switch. This structure is scalable, high-speed, simple, practical, and low-cost, exploiting the workhorses of todays optical communications systems: arrayed waveguide gratings, distributed feedback lasers, LiNbO3 switches, and low-speed photodiodes and electronics (~ 100 MHz). We also propose a solution to alleviate the sophisticated label swapping processing required in generalized multiprotocol label switching (GMPLS) networks. We time-multiplex the binary multiwavelength labels for the entire optical label switching path. We examine the performance of both schemes experimentally by verifying successful routing and error-free transmission.

Ultrafast FWM Self Routing between 10 Ports of Spectral Amplitude Coded 10 Gb/s Packets set on a 25 GHz Grid with Unequally Spaced Bins

A novel ultrafast self routing system is demonstrated using four-wave-mixing of 10 Gb/s packets spectrally-encoded in 25 GHz grid bins which are unequally spaced. Codes with a maximum separation of 1.6 nm enable routing to 10 different ports.

Packet switched networks with photonic code processing

In this paper we present our study of all optical label encoding and ultrafast processing to route packets through optical networks. Our investigations include new network topologies, novel photonic components and performance analysis. We propose a label stacked packet switching system using spectral amplitude codes (SAC) as labels. We have developed enabling technologies to realize key photonic components for generation, correlation (identification) and conversion (swapping) of SAC-labels. We generate and identify the labels with fibre Bragg gratings (FBGs) encoders used in transmission. Furthermore, we demonstrate a static, all-photonic code-label converter based on a semiconductor fiber ring laser that can be used for label swapping of SAC-labels. We also address the design of dedicated receivers for optical burst detection. For this, we propose a novel architecture for a burst mode receiver module. In the system studies, we have shown by simulations that the throughput of standard Ethernet passive optical networks (E-PONs) can be substantially increased by the use of data encoded with SACs to achieve optical code division multiple access over passive optical networks (OCDMA-PONs). In the paper, we present recent results for all of these photonic technologies and we discuss how they can enable flexible packet switched networks.