ece228 lecture 18 [Compatibility Mode]

ece228 lecture 18 [Compatibility Mode] - Bowers ECE 228A...

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Unformatted text preview: Bowers ECE 228A Optical Amplification and Switching Lecture #18 John Bowers CE 228A ECE 228A Read Chapter 6 Final: Monday, June 7 12-3 pm 2 sided 8.5 x 11” crib sheet Problems: ) aser design 1) Laser design 2) Photodetector design 3) Amplifier design 4) Link design including issues of dispersion, loss, fibers, laser design ) eneral knowledge 5) General knowledge Bowers ECE 228A Critical Elements for Networks • Transmitters • Receivers • Amplifiers • Switches • Add/drop multiplexers (ADMs, ROADMs) • Wavelength multiplexers, demultiplexers • Polarization Controllers Bowers ECE 228A Concepts • Connectivity (from least to best) – Partial connection – Full connection – Rearrangably nonblocking – Wide sense nonblocking (any input can be connected to any output provided a particular algorithm is followed) trictly nonblocking (any input can be connected to any – Strictly nonblocking (any input can be connected to any output) – Redundant strictly nonblocking Bowers ECE 228A Switch architectures – Crossbar (strictly nonblocking if only deflections down are allowed) – Benes (rearrangably nonblocking) – Clos – Shuffle – Banyan Bowers ECE 228A Switch Types • Space switches • Time switches • Frequency switches Bowers ECE 228A Benes Network Benes networks are rearrangeably nonblocking. They take fewer elements than trictly nonblocking networks They are hence preferred when all N connections are strictly nonblocking networks. They are hence preferred when all N connections are requested simultaneously. Otherwise, they require a brief interruption of service. Requires 2log2(N)-1 stages of N/2 couplers each Bowers ECE 228A Fully connected networks • A fully connected network means any input can be onnected to connected to any output. Bowers ECE 228A Clos Networks • Common in large electrical switches • May become common to make very large optical switches • Strictly nonblocking • ewer stages than crossbar Fewer stages than crossbar • N=number of inputs and outputs • n=number of inputs/stage in first stage • m=number of inputs/stage in 3d stage • r=# of switches in stage 1 (and 3) =2(n )+1=2n • m=2(n-1)+1=2n-1 Bowers ECE 228A 5 Stage Clos • Used by Ciena for large Core Directors • Optical interconnects between stages 1 and 3 and 4 and 5. • (OEOEOEO switch) Bowers ECE 228A Advantage of Clos over Crossbar Bowers ECE 228A Dilation • Dilation (extra stages of switching per element) increase the extinction ratio and reduces crosstalk. • Common in optical switches, particularly acousto-optic switches. • No dilation: – 2 dB loss – 20 dB extinction ratio 8 dB SNR – 18 dB SNR • Dilated switch: – 4 dB loss – 40 dB extinction ratio 6 dB SNR – 36 dB SNR Bowers ECE 228A Dilation • Dilation (extra stages to increase the extinction ratio and reduces crosstalk....
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ece228 lecture 18 [Compatibility Mode] - Bowers ECE 228A...

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