Optical generation and distribution of continuously tunable millimeter-wave signals using an optical phase modulator

TLDR

The paper proposes generating and distributing two wide bands of continuously tunable millimeter‑wave signals using an optical phase modulator and a fixed optical notch filter. The method employs the phase modulator and notch filter to produce the mm‑wave bands, with dispersion compensation needed to suppress odd‑order electrical harmonics and prevent signal fading over fiber. Theoretical analysis shows odd‑order harmonics cancel while even‑order harmonics appear when the optical carrier is filtered, and experimental results demonstrate that tuning the drive from 18.8–25 GHz yields high‑quality mm‑wave bands at 37.6–50 GHz and 75.2–100 GHz locally and remotely, avoiding the DC bias‑drift problem of intensity modulators.

Abstract

In this paper, we propose an approach to generate and distribute two wide bands of continuously tunable millimeter-wave (mm-wave) signals using an optical phase modulator and a fixed optical notch filter. We demonstrate theoretically that the odd-order electrical harmonics are cancelled and even-order electrical harmonics are generated at the output of a photodetector when the optical carrier is filtered out from the phase-modulated optical spectrum. Analysis shows that dispersion compensation is required in order to maintain the suppression of the odd-order electrical harmonics, in order to eliminate signal fading of the generated electrical signal when the optical signal is distributed using conventional single-mode optical fiber. It is experimentally demonstrated that, when the electrical drive signal is tuned from 18.8-25 GHz, two bands of mm-wave signals from 37.6 to 50 GHz and from 75.2 to 100 GHz with high signal quality are generated locally and remotely. This approach does not suffer from the direct current (dc) bias-drifting problem observed when an optical intensity modulator is used.