Optical switch
A 2 × 2 optical switch routes light bar (straight through) or cross (across), leaking a little the other way.
Ports
Ports 1 and 2 on one side, 3 and 4 on the other.
- Bar: 1 to 3, and 2 to 4.
- Cross: 1 to 4, and 2 to 3.
The model
The path the switch is set to has an amplitude \(a = 10^{-\ell/20}\) for an insertion loss \(\ell\) (dB). The other path leaks at the crosstalk \(X\) further down, \(10^{-(\ell + X)/20}\):
\[\text{bar:}\quad \mathbf S_{13} = \mathbf S_{24} = a\,\mathbf I,\quad \mathbf S_{14} = \mathbf S_{23} = a\,10^{-X/20}\,\mathbf I,\]and the other way round for cross. It is the same in both directions.
Settings
| Field | Default | Meaning |
|---|---|---|
cross | 0 | State (0 bar, 1 cross) |
loss | 0.8 | Insertion loss (dB) |
xt | 50 | Crosstalk (dB) |
From the tool's own tables, file format version 1: the names are those in a .jekray file.
The state is 0 for bar and 1 for cross. As a number it can be swept, to compare the two.
Assumptions
- The switch is in one state or the other: there is no switching time and no state in between.
- Its loss and crosstalk do not depend on wavelength or polarisation, and the leak adds no phase.