1. Current Status of Optical Communication on PCB
Manasa.K
CWB0912002, FT-2012
M. Sc. (Engg.) in Electronic System Design
Engineering
Module leader: Mr. Ugra Mohan Roy
M.S.Ramaiah School of Advanced Studies
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2. Overview
• Introduction
• Optical Printed Circuit Board
• Optical Data Communication
• Current Status of Optical data communication on PCB
• Advantages
• Disadvantages
• Conclusion
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3. Introduction
• As requirement for bandwidth increases in the systems, it leads to many
problems such has increased power consumption, effects of crosstalk,
electromagnetic interference, effect of interconnect density on performance
etc.
• These problems can be addressed using optical interconnects in both inter
PCB communication and intra PCB communication.
• The concept of O-PCB is very much like that of electrical printed circuit board
(E-PCB) except for the use of optical wires for optical signals.
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4. Optical-Printed Circuit Board
• The O-PCB is defined as a flat modular board, substrate, or chip containing a
planar array of optical wires, circuits, and devices to perform the functions of sensing,
storing, transporting, routing, distributing, and processing optical signals.
• Polymer waveguides are the popular choice for optical interconnects due to low
cost, suitability for mass production, low optical loss and compatibility with PCB
materials.
• Increase of speed through transmission of multiple wavelengths into a single
channel (WDM)
• Light source: LED, Laser
• Interconnect medium: Polymer, glass, silicon etc.
• Detector: Si, InGaAs, InP
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5. Optical Fiber communication
The signals or the information from the transmitter is sent to receiver
over the optical fiber.
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6. Optical Fiber communication
The basic components of optical interconnect system consists of
Optical modulator: it has 2 inputs, from laser and electrical signal from CMOS
driver circuit. It is used to convert electrical signals to optical signals for the
transmission.
Optical Coupler: used to inject light into the optical system
Waveguide: consists of dielectric materials with high index of refraction
surrounded by the a material of lower refractive index.
Optical Switches: are used in optical routing, to route the light from waveguide to
different locations
Photo detector: used to detect the light pulse and convert it to photo current.
Trans Impedance Amplifier: used to amplify the photo current.
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7. Current Status of Optical communication
• VCSELs operating at a wavelength range of 1200 to1600 nm using the InP or
AlGaAS based process technology promises higher data rate with low power
consumption.
• Xyratex Technology, IBM Zurich and Siemens C-Labs, developed a new type of
multilayer hybrid PCB in which optical waveguide interconnects are used for the
highest data rates, with copper tracks for lower data rates and for power lines and
ground.
• Polymer waveguides provide an integrated means to route optical signals similar
to how copper lines route electrical signals," explains Dr. Bert Jan Offrein, thin
sheets of optical waveguide show no curling and can bend to a 1 mm radius and is
stable at extreme operating conditions including 85% humidity and 85°C. This new
polymer, based on silicone materials, offers an optimized combination of properties
for the integration in established electrical printed circuit board technology.
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8. Current Status of Optical communication
• Technology suitable for low cost mass production is multimode polymer buried
channel optical waveguide interconnections within layers in the multilayer PCB.
• Integrating a silicon-based photodiode with a silicon amplifier at the optical receiver
has high reliability and it is of low cost.
• Scanned-detection drastically improves signal-to-noise ratio (SNR).
The collection-lens is scanned synchronously with the mirror that is used to scan
the laser-spot to increase SNR.
Detected signal after the scanned detection
system
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9. Advantages
•
Supports parallelism
•
Low input/output driving energy
•
Capability to withstand electromagnetic interference
•
Low dispersion
•
Can be operated at high frequencies
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10. Disadvantages
• One of the greatest challenges of optical PCB technology is the difficulty of
aligning components to conventional optical waveguide structures in order to
establish and maintain an optical connection.
• The optical devices should be integrated with the electrical driving circuits.
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11. Summary
• High bandwidth requirement is the major issue in all the system, the solution for
this is the use of optical communication system on PCBs.
• O-PCB consists of arrays of optical wires which helps in processing optical
signals.
• Polymer waveguide is the best material to be used for mass production, and it is
compatible with PCB materials.
• The basic components of optical communication are transmitter, receiver and the
optical fiber.
• VCSELs operating at a wavelength range of 1200 to1600 promises higher data
rate with low power consumption.
• Scanned-detection drastically improves signal-to-noise ratio (SNR)
• Difficulty in aligning components to conventional optical waveguide structures.
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12. References
• Sumita Mishra Overview of Optical Interconnect Technology (1st July 2013)
•
M.Immonen Development Of Electro-optical Pcbs With Polymer Waveguides For
High-speed On-board Optical Interconnects TTM Technologies Inc Finland (1st
July 2013)
• Dr. Bert Jan Offrein (4 February 2013) Dow Corning and IBM Scientists Develop
New Materials for Board-Level Photonics available from <
http://www.zurich.ibm.com/news/13/photonics.html > ( 5th July 2013)
• Pamidighantam V Ramana Bi-Directional Optical Communication at 10 Gb/s on
FR4 PCBUsing Reflow Solderable SMT Transceiver Institute Of Microelectronics
Japan (5th July 2013)
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