K. Okamoto

High-performance optical-label switching packet routers and smart edge routers for the next-generation Internet

This paper discusses the architecture, protocol, analysis, and experimentation of optical packet switching routers incorporating optical-label switching (OLS) technologies and electronic edge routers with traffic shaping capabilities. The core optical router incorporates all-optical switching with contention resolution in wavelength, time, and space domains. It is also capable of accommodating traffic of any protocol and format, and supports packet, flow, burst, and circuit traffic. The edge router is designed to achieve traffic shaping with consideration for quality of service and priority based class-of-service. Simulation results show packet loss rates below 0.3% at load 0.7 and jitter values below 18 /spl mu/s. The traffic shaping reduces the packet loss rate by a factor of /spl sim/5 while adding negligible additional latency. The OLS core routers and the electronic edge routers are constructed including the field-programmable-gate-arrays incorporating the wavelength-aware forwarding and contention resolution algorithms. The experiment shows optical-label-based packet switching with a packet loss rate near 0.2%.

Rapidly switching all-optical packet routing system with optical-label swapping incorporating tunable wavelength conversion and a uniform-loss cyclic frequency AWGR

This letter discusses an experimental demonstration of a rapidly switching all-optical packet routing system with optical-label switching and all-optical label-swapping capabilities. The optical routing system optically extracts the subcarrier optical-label content, compares it against the forwarding table, makes packet forwarding and label-swapping decisions, and forward the packet to the desired output with a newly updated subcarrier optical label. The packet switching fabric included a combination of rapidly tunable wavelength conversion and a uniform-loss cyclic frequency 8/spl times/8 arrayed waveguide grating router. The packet routing system achieved 600-ps switching time and 250-ns forwarding decision time. Accumulated packet bit-error-rate measurements confirm the successful error-free packet routing with all-optical label-swapping.

End-to-end contention resolution schemes for an optical packet switching network with enhanced edge routers

This paper investigates contention resolution schemes for optical packet switching networks from an end-to-end perspective, where the combined exploitation of both core routers and edge routers are highlighted. For the optical-core network, we present the architecture of an optical router to achieve contention resolution in wavelength, time, and space domains. Complementing the solution involving only the core router intelligences, we propose performance enhancement schemes at the network edge, including a traffic-shaping function at the ingress edge and a proper dimensioning of the drop port number at the egress edge. Both schemes prove effective in reducing networkwide packet-loss rates. In particular, scalability performance simulations demonstrate that a considerably low packet-loss rate (0.0001% at load 0.6) is achieved in a 16-wavelength network by incorporating the performance enhancement schemes at the edge with the contention resolution schemes in the core. Further, we develop an field-programmable gate-array (FPGA)-based switch controller and integrate it with enabling optical devices to demonstrate the packet-by-packet contention resolution. Proof-of-principle experiments involving the prototype core router achieve an error-free low-latency contention resolution.

High-fidelity line-by-line optical waveform generation and complete characterization using FROG

A stable optical frequency comb with 20-GHz spacing is shaped by a compact integrated silica arrayed waveguide grating (AWG) pair to produce optical waveforms with unprecedented fidelity. Complete characterization of both the intensity and phase of the crafted optical fields is accomplished with cross-correlation frequency resolved optical gating (XFROG) which has been optimized for periodic waveforms with resolvable modes. A new method is proposed to quantify, in a single number, the quality of the match in both the amplitude and phase between the measured optical waveform and the target waveform.

Demonstration of all-optical packet switching routers with optical label swapping and 2R regeneration for scalable optical label switching network applications

This paper investigates comprehensive operation and experimentation of an all-optical packet switching router with optical label swapping and reamplification and reshaping (2R) regeneration, capable of multihop operation and Internet protocol (IP)-client interoperability. In particular, the experiment demonstrates successful packet switching and transport up to 11 hops with 10/sup -9/ bit-error rate and error-free up to four hops. Furthermore, this paper demonstrates the optical label switching (OLS) core router and edge routers working together to support IP-client-to-IP-client packet transport and switching across the optical label switching network. The edge router generates an optical label based on the IP header content of the packet and generates an optical label encoded packet, which subsequently ingresses into the OLS network. The optical label switching router (OLSR) forwards the packet with all-optical label swapping at each hop with 2R regeneration. The 2R regeneration leads to an experimentally measured negative penalty and a successful experimental demonstration of multihop cascaded OLSR operation with the edge routers interfacing with IP clients. The successful IP-client-to-IP-client packet forwarding via the edge routers and the cascaded multihop OLSR with all-optical label swapping indicate the viability of OLS in the scalable and transparent IP-over-optical Internet.

Design and experimental demonstration of a variable-length optical packet routing system with unified contention resolution

This paper presents theoretical design, network simulation, implementation, and experimental studies of optical packet routing systems supporting variable-length packets. The optical packet switching network exploits unified contention resolution in core routers in three optical domains (wavelength, time, and space) and in edge routers by traffic shaping. The optical router controller and lookup table, implemented in a field-programmable gate array (FPGA), effectively incorporates the contention resolution scheme with pipelined arbitration of asynchronously arriving variable-length packets. In addition, real-time performance monitoring based on the strong correlation between the bit-error rates of the optical label and those of the data payload indicates its application in optical time-to-live detection for loop mitigations. Successful systems integration resulted in experimental demonstration of the all-optical packet switching system with contention resolution for variable-size packets.

Compact 10 GHz loopback arrayed-waveguide grating for high-fidelity optical arbitrary waveform generation

We demonstrate a high-performance optical arbitrary waveform shaper based on a single 10 GHz arrayed-waveguide grating with 64 loopback waveguides and integrated amplitude and phase modulators on each waveguide. The design is compact and self-aligning and allows for bidirectional operation. The devices complex transfer function is manipulated and measured over the full 640 GHz passband. To demonstrate optical arbitrary waveform shaping, high-fidelity 15-line shaped waveforms are measured with cross-correlation frequency-resolved optical gating.

Demonstration of a fast-reconfigurable silicon CMOS optical lattice filter

We demonstrate a fully-reconfigurable fourth-order optical lattice filter built by cascading identical unit cells consisting of a Mach-Zehnder interferometer (MZI) and a ring resonator. The filter is fabricated using a commercial silicon complementary metal oxide semiconductor (CMOS) process and reconfigured by current injection into p-i-n diodes with a reconfiguration time of less than 10 ns. The experimental results show full control over the single unit cell pole and zero, switching the unit cell transfer function between a notch filter and a bandpass filter, narrowing the notch width down to 400 MHz, and tuning the center wavelength over the full free spectral range (FSR) of 10 GHz. Theoretical and experimental results show tuning dynamics and associated optical losses in the reconfigurable filters. The full-control of each of the four cascaded single unit cells resulted in demonstrations of a number of fourth-order transfer functions. The multimedia experimental data show live tuning and reconfiguration of optical lattice filters.

Advanced optical-label routing system supporting multicast, optical TTL, and multimedia applications

This paper reports on modern features of the optical-label switching (OLS) system in support of multicast, optical time-to-live (TTL), and video-streaming applications. We first propose and demonstrate optical-label switching core router architecture with multicast function. The multicast switching architecture provides reduced complexity and effective multicast contention resolution compared to conventional multicast-capable switching fabric. A proof-of-principle experiment successfully showed packet multicast forwarding with contention resolution. The all-optical TTL monitors the healthiness of the packet, and prevents degraded packets from traveling or looping further in the network. The experiment demonstrated successful packet discards based on optical signal-to-noise ratio degradation. Finally, we present an optical label switching edge router that supports aggregation, quality of service, and class of service, and we further demonstrate a video streaming application between Ethernet clients through the OLS edge routers and a core router. The modern features of OLS routers proposed and demonstrated in this paper indicate the viability of OLS technologies in future photonic Internet in support of modern applications.

Error-free multihop cascaded operation of optical label switching routers with all-optical label swapping

This paper discusses multihop routing, all-optical label swapping operation of optical label switching routers that make real-time decisions based on the label and the forwarding table. The switching fabric conducts data regeneration and label rewriting.