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.

Electronic Cisco Routers Long Distance Optical Communication Network

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.

Optical Input Ports Optical Output Ports Packet All-Optical Router Network Nodes

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.

All-Optical Buffer Packet Feedback Loop Optical Input Port Optical Output Port Buffers to store packets All-Optical Router

All-Optical Buffer

Project Goals Build a large scale buffer prototype. Help design & implement buffer switching control. Simulate routing control signals & test buffer behavior.

All-Optical Buffer Feedback Loop Computer Switching Control Signal Generator Routing Signals Optical Transmitter Optical Receiver Optical Signal Electronic Signal

All-Optical Buffer

Making the Optical Buffer Semiconductor Optical Amplifiers (SOA). Isolators. Attenuators. Couplers and Splitters. Band Pass Filter. Optical Fiber.

Input Output Buffer OCPN Lab

All-Optical Buffer

Controlling the Optical Buffer

4 2

Optical Buffer FPGA Signal Generator 00 – Let packet through 10 – Store packet (Write) 01 –Release packet (Read) 11 – Do nothing Read/Write Optical Amps ON/OFF

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.

All-Optical Buffer

Circulating Packets

Optical Transmitter Oscilloscope 0 Circulations 1 Circulation 3 Circulations 2 Circulations Power vs. Time

Buffer parameters: Path = 120ns & Loop = 60ns. One circulation → Packet relative delay = 180ns.

Path Loop

All-Optical Buffer

Measuring Bit-Error-Rate

Optical Transmitter Optical Buffer Optical Receiver Sends Packets Detects/Analyzes Packets Stores Packets

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.

All-Optical Buffer

Power Penalty Analysis

1.E-11 1.E-10 1.E-09 1.E-08 1.E-07 1.E-06 1.E-05

• 52.5
• 52
• 51.5
• 51
• 50.5
• 50
• 49.5
• 49
• 48.5

Receiver Power (dBm) Bit Error Rate

0 Circulations 1 Circulations 2 Circulations 3 Circulations 4 Circulations 5 Circulations 6 Circulations 7 Circulations 8 Circulations

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.

Kamelian Semiconductor Optical Amplifier (SOA) Optical Output Optical Input Optical Buffer Feed-back architecture

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.