All-Optical Buffer Tomas A. Tinoco Electrical Engineering and - PowerPoint PPT Presentation

All-Optical Buffer Tomas A. Tinoco Electrical Engineering and Computer Science Diablo Valley College University of California, Berkeley Optical Communications and Photonic Networks Group Mentor: John Mack University of California, Santa Barbara Project funded by: DARPA

All-Optical Buffer Current Communication Networks � Information broken into packets (e. g. Internet). � Packets transmitted optically. � Packets routed electronically → O/E & E/O conversions. � Electronic switching speed <<< Optical transmission capacity. Long Distance Optical Communication Network Electronic Cisco Routers

All-Optical Buffer Future Communication Networks � Optical Routers. � Keep data in optical domain → No O/E & E/O conversions. � Routing capacity x100. � Lower power consumption and cost . Packet All-Optical Router Network Nodes Optical Input Optical Output Ports Ports

All-Optical Buffer Key Component � All-Optical Buffer. � Necessary for avoiding packet collisions inside optical routers. � Exploit time domain → Store light for a variable time period. � Use a fiber delay loop to make packet circulate. Buffers to store packets Feedback Loop All-Optical All-Optical Packet Router Buffer Optical Optical Input Port Output Port

All-Optical Buffer Project Goals � Build a large scale buffer prototype. � Help design & implement buffer switching control. � Simulate routing control signals & test buffer behavior. Feedback Loop Optical Signal Electronic Signal All-Optical Optical Optical Buffer Transmitter Receiver Switching Control Routing Signals Signal Computer Generator

All-Optical Buffer Making the Optical Buffer � Semiconductor Optical Amplifiers (SOA). � Isolators. � Attenuators. � Couplers and Splitters. � Band Pass Filter. � Optical Fiber. Buffer OCPN Lab Input Output

All-Optical Buffer Controlling the Optical Buffer � Turn SOAs ON/OFF using a Field Programmable Gate Array (FPGA). � Specify path and loop duration in FPGA clock cycles. � Simulate Electronic Random Access Memory (RAM) → Read/Write. 00 – Let packet through Optical 10 – Store packet (Write) Buffer 01 –Release packet (Read) 4 Optical Amps 11 – Do nothing ON/OFF 2 Read/Write Signal Generator FPGA

All-Optical Buffer Circulating Packets � Buffer parameters: Path = 120ns & Loop = 60ns. � One circulation → Packet relative delay = 180ns. Loop Oscilloscope Optical Transmitter Path Power vs. Time 0 Circulations 1 Circulation 2 Circulations 3 Circulations

All-Optical Buffer Measuring Bit-Error-Rate � Send packets using an Optical Transmitter (6.4GHz). � Measure Bit-Error-Rate = Errors/Total Number of Bits Received. � Find power penalty for different # of circulation. Optical Buffer Optical Optical Transmitter Receiver Stores Packets Detects/Analyzes Sends Packets Packets

All-Optical Buffer Power Penalty Analysis 1.E-05 1.E-06 0 Circulations 1.E-07 1 Circulations Bit Error Rate 2 Circulations 3 Circulations 4 Circulations 1.E-08 5 Circulations 6 Circulations 7 Circulations 1.E-09 8 Circulations 1.E-10 1.E-11 -52.5 -52 -51.5 -51 -50.5 -50 -49.5 -49 -48.5 Receiver Power (dBm)

All-Optical Buffer Summary � Optical Routers require a way of storing packets. � Solution: Feed-back optical buffer. � Implementation: 2x2 switch using SOAs. � Limitation: More circulations → Signal quality decreases. Optical Optical Input Output Optical Buffer Kamelian Semiconductor Optical Feed-back architecture Amplifier (SOA)

All-Optical Buffer Future Work � Improve buffer to achieve more # of circulation. � Build and test an optical router that uses optical buffers. � Integrate optical buffers on microchips. Acknowledgements CNSI, INSET, John Mack and all the members of the OCPN group.