Electromagnetic Fields and Waves: Notes, Solved Problems and Interactive Lab

Two short calculations tied to the applications, with the fibre results of this section and the resonance formula of the dielectric resonator. They use no new physics. A good way to use them: read the given quantities, produce the formula from the corresponding application yourself, and only then put the numbers in. Constants: $c = 3 \times 1 0^{8} m/s$ , $η_{0} = 120 π Ω$ .

Worked example 7.6.1

A 1550 nm fibre span

Given. An $80 km$ span of the fibre of Problem 7.6.3 ( $0.2 dB/km$ at $1550 nm$ , $0.35 dB/km$ at $1310 nm$ , $D = 17 ps/ (nm km)$ at $1550 nm$ ). Transmitter $0 dBm$ , receiver needs $- 24 dBm$ at $10 Gb/s$ . Two connectors ( $0.5 dB$ each), $19$ splices ( $0.05 dB$ each).

Find. (a) The power budget and margin at $1550 nm$ . (b) The same at $1310 nm$ . (c) The chromatic spread for a source width of $0.1 nm$ and of $0.01 nm$ , against the $100 ps$ bit slot. (d) What would modal dispersion do in the multimode fibre of Problem 7.6.4?

Try it yourself first.

cf. Application 7.6.1

Worked example 7.6.1: A 1550 nm fibre span