OPTICAL POLARIZATION MODULATOR EMPLOYING INTERFEROMETRIC STRUCTURES

摘要

An optical polarization modulator has an interferometric structure including, in at least one of two branches, a device causing the signal fractions in the two branches to assume an amplitude ratio depending on the value taken by a control signal, and a desired relative phase. In one embodiment, the amplitude modulators are multiple quantum well asymmetric cavity Fabry-Perot devices biased in a complementary manner by binary signals, the levels of which are associated with voltage values such as to bring the devices to maximum absorption or maximum reflectivity conditions respectively; thus for each signal level only one of the two cavities reflects part of the received radiation. The optical signal to be modulated is applied to one of the cavities with a first polarization state that is maintained in the reflected radiation, and to the other cavity in a polarization state resulting in a second state of polarization in the reflected radiation.