Theory 016/Optics & Photonics

Crosstalk Is an Index Ratio

The claim

Crosstalk between photonic waveguides is set by the ratio of index contrast to spacing rather than by spacing alone, so a tighter spacing can be tolerated with higher contrast.

01The mechanism

Mode overlap decays exponentially with the ratio of spacing to confinement, and confinement is set by contrast.

02Predictions

P1Crosstalk should collapse onto the ratio.
P2Higher contrast should permit tighter spacing.

03Refutation

Crosstalk depending on spacing alone would remove the contrast term.