An engineer wants a travelling-wave lithium niobate phase modulator whose…
PHYSICS · Multi-part · Fermi University Physics · Optics & Photonics · Polarisation and anisotropic media · Polarisation and anisotropic media
What an Instrument Can See, Ch Modulating light: electro-optic, acousto-optic and magneto-optic devices
Problem
An engineer wants a travelling-wave lithium niobate phase modulator whose velocity-mismatch-limited 3 dB bandwidth reaches at least 10 GHz. Take the microwave and optical group indices of x-cut lithium niobate as the typical values nμ≈2.20 and ng≈2.15.
((a)) Estimate the maximum electrode length L that still reaches a 10 GHz bandwidth.
((b)) A practical chip carries a 5.0 cm electrode. Estimate its bandwidth and judge whether it meets the 10 GHz specification.