Optical modulator for CATV systems

Abstract

A resonantly enhanced external electro-optic modulator reduces required drive power. The modulator has a coupling structure that efficiently couples power from a feed line into the resonator and eliminates the need for a terminal impedance. The modulator can be driven by a RF signal that is designed to suppress Stimulated Brillouin Scattering (SBS) in a long haul, high power fiber optic link, such as that used to transmit analog CATV signals. The modulator can also be used to depolarize an optical signal. A ring resonator includes a portion located outside the active area of the modulator in order to provide a space-efficient structure. The ring resonator can include one or more coaxial cable portions that are tuned to provide resonance at one or more frequencies that are matched to the input RF drive signal. A pre-chirping phase modulator and intensity modulator which are driven by a common RF/DC bias signal also provide a space- and power-efficient structure by eliminating the need for a separate DC bias electrode. Compared to other adjustable chirp devices, there is no need to pre-distort both branches of the intensity modulator. An integrated electro-optic device includes a resonantly enhanced modulator, a pre-chirping modulator, and an intensity modulator arranged serially and fabricated in a common substrate.

Dependencies are inferred from the claim text.