Methods, devices, and systems are described for free space optical communication. An example method can comprise generating a first linearly polarized optical signal and converting the first linearly polarized optical signal to a first circularly polarized optical signal. The first circularly polarized optical signal can be output into free space. The method can comprise converting a second circularly polarized optical signal, received via free space, to a second linearly polarized optical signal. The second linearly polarized optical signal can have a linear polarization different than a polarization of the first linearly polarized optical signal. The method can comprise directing, via a polarizing beam splitter, the second linearly polarized optical signal to a first path separate from a second path from which the polarizing beam splitter received the first linearly polarized optical signal.