MULTIPLEXING/DEMULTIPLEXING SCHEME FOR LASER COMMUNICATIONS USING RESONANT FARADAY ROTATION

The primary objective of this research is to develop a novel optical multiplexing/demultiplexing device to combine many separate laser channels for communications applications. For both free space and fiber optic laser communications it is desirable to have a multiplexing scheme which has many channels close together in wavelength (<1nm) and which does not require the use of angularly dispersive optical elements. This project will test an efficient multiplexing/demultiplexing scheme using polarization optics, where additional channels are combined through a polarizer, and then the polarization of the new channel is rotated to coincide with the polarizations of the previous channels using selective polarization rotation in an atomic vapor in a magnetic field (Faraday rotation). The process also workds in reverse for demultiplexing, and it is believed that sufficient channel separation can be achieved to reduce crosstalk to an acceptable level, even at high channel bandwidths. The method will be tested for free space laser communications at 852 nm using cesium vapor, and may be adaptable to fiber optic laser wavelengths using molecular vapors.