Microwave harmonic generation in fiber-optical links

Abstract

Optical transmission of microwave (MW) and millimeter-wave (MMW) signals has become an intensive re- search area in the last decade. There is a growing interest in optical processing of MW signals [1, 2], phased array applications [3] and wireless distribution of broadband data in fiber-fed MMW subscriber access systems [4 – 10]. This paper extends the existing models of MW/MMW optical links that are based on optical intensity [10, 11]. The model is suitable for estimating harmonic levels of the MW modulation signal generated in the optical path. Considering a MW fiber-optic link both the optical transmitter and the receiver are responsible for harmonic generation. Furthermore, the optical fiber itself inserted between the transmitter and receiver induces harmonics due to dispersion. Exact modelling of harmonic generation requires a calculation based on the optical field instead of on a purely intensity basis [12 – 14].