Electrically controllable optical attenuator

摘要

A known form of electrically controlled optical attenuator is formed by a mach Zehnder waveguide configuration with a variable refractive index element in one arm to modify the undulatory spectral characteristic of the network to give a specific attenuation at a specific wavelength. The spectral characteristic of the network makes the attenuation that it provides wavelength dependent. An attenuator with a wavelength dependence of reduced magnitude is provided by the series combination of two Mach Zehnder networks, one having an electrically controllable optical path length adjuster in its longer interference arm, and the other with its adjuster in its shorter arm.