Julien Penon

Spectral-Amplitude-Coded OCDMA Optimized for a Realistic FBG Frequency Response

We develop a methodology for numerical optimization of fiber Bragg grating frequency response to maximize the achievable capacity of a spectral-amplitude-coded optical code-division multiple-access (SAC-OCDMA) system. The optimal encoders are realized, and we experimentally demonstrate an incoherent SAC-OCDMA system with seven simultaneous users. We report a bit error rate (BER) of 2.7times10-8 at 622 Mb/s for a fully loaded network (seven users) using a 9.6-nm optical band. We achieve error-free transmission (BER<1times10-9) for up to five simultaneous users

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

An Innovative Receiver for Incoherent SAC-OCDMA Enabling SOA-Based Noise Cleaning: Experimental Validation

We propose a new low complexity receiver for spectral amplitude optical coded division multiple access (SAC OCDMA) that enables intensity noise reduction using semiconductor optical amplifiers (SOAs). Compared to the standard receiver requiring two optical filters at the receiver side, our receiver requires only one optical filter. While a 1.4-dB power penalty in incurred, network capacity is unchanged, i.e., BER floors due to intensity noise have the same level. The primary motivation for the low complexity receiver is not reduced component count, but rather modifying the receiver so that promising SOA noise mitigation techniques might be employed to increase system capacity. SOA noise cleaning suffers from a major limitation: filtering after the SOA can negate most of the signal enhancement, the so-called post SOA filtering issue. The only solution to date for the post-SOA filtering effect in SAC-OCDMA is prohibitively complex McCoy , J. Lightw. Technol., vol. 25, no. 1, pp. 394-401, Jan. 2007, i.e., requiring multiple SOAs per client. We demonstrate that our proposed receiver drastically limits the client side filtering, thus maintaining noise suppression and overcoming the post-SOA filtering effect. We compare BER at up to 10 Gb/s with and without noise cleaning. When a noise cleaning module is used, BER improvement of several orders-of-magnitude is observed when only a few users are active in the network. Examination of the noise properties, however, leads us to conclude that highly populated networks will have diminished improvement.

Balanced Detection of Correlated Incoherent Signals: A Statistical Analysis of Intensity Noise With Experimental Validation

We study the balanced detection of broadband incoherent optical signals-signals characterized by high-intensity noise. We consider signals generated from a single incoherent source with two types of correlation: identical spectra, but delayed in time, and overlapping, nonidentical spectra but zero time delay. Our statistical analysis yields equations for the probability density function (pdf) of the balanced detector output for partially correlated input signals based on easily measured system parameters (power spectral densities in one case, relative time delay in the other). Using analytical tools we derive expressions for output pdfs giving extremely good prediction of measured pdfs for signals with correlation coefficient up to 95%. The analytic expressions can be used to characterize system performance, in particular, bit error rate for communications systems.

Probing the Limits of PON Monitoring Using Periodic Coding Technology

We probe the limits, both experimentally and analytically, of passive optical network (PON) monitoring using periodic coding technology. The experimental demonstration focuses on a 16 customer PON with a 20 km feeder fiber followed by either a single cluster or a tiered hierarchy. A directly modulated laser modulated at 1 GHz was used to generate the monitoring probe signals. The measured data from the experimental setup was fed to a reduced complexity maximum likelihood sequence estimation (RC-MLSE) algorithm to detect and localize the customers. Three different PON deployments were tested. We demonstrate improved monitoring robustness when using a variable threshold for networks with a tiered geographic distribution. While only a 16 customer PON was tested, our experimental setup had 18 dB margin in the total loss budget corresponding to splitting losses for 64 customers. We investigate analytically the total permissible loss budget of the monitoring system operating in the 1650 nm waveband as a function of receiver specifications. We examine the effect of resolution in the analog-to-digital conversion on the correlation peaks that form sufficient statistics for the RC-MLSE algorithm. Resolution affects both the RC-MLSE algorithm and the use of signal averaging to improve signal-to-noise ratio. We find that the monitoring system is able to monitor current PON standards with inexpensive, commercially available electronics.

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

Incoherent SAC OCDMA system at 7×622Mbps

We demonstrate experimentally an incoherent spectral amplitude coding OCDMA system with seven simultaneous users. BER better than 5times10-6 at 622 Mbps is reported for a fully loaded network; error-free transmission is obtained for five simultaneous users.

Self-Routed Packets with Encoded Payload and Stacked Optical Code Labels

We propose label switching with an encoded payload and implicit stacked spectral amplitude code labels. We experimentally demonstrate all-optical packet switching over 80 km of fiber in a network with two forwarding nodes.

All-optical Label Stacking Capacity for Packet Switching Using Spectral Amplitude Code Labels

We analyze the stacking capacity of spectral-amplitude-codes labels using 12.5 to 50 GHz bin widths and label duration from 0.1 to 1 mus. Up to 240 1mus-labels can be stacked using 25 GHz bins

Simulation of Real SAC-OCDMA under Both S-ALOHA and R3T Random Access Protocols

We simulate both the throughput and the delay of an experimental 7times622 Mbps spectral amplitude coding (SAC)-OCDMA system. Our results reveal that the round robin receiver/transmitter (R3T) protocol performs better than S-ALOHA CDMA protocol and provides a 4.5 dB improvement