Dynamic control of polarization states with barium titanate integrated photonic devices

We demonstrate continuous control of polarization from a two-dimensional grating outcoupler of a modified Mach–Zehnder interferometer, fabricated in barium titanate grown on a silicon substrate. The polarization state of out-coupled light at λ≈1550 nm is measured as a function of wavelength and applied bias. We show wavelength-dependent polarization switching from nearly entirely left hand circularly, to linearly, to nearly entirely right hand circularly polarized light. We also demonstrate voltage-tuning of the polarization state of the out-coupled light and achieve switching between left- and right-hand circularly polarized output with <10 V applied bias and an effective VπL∼0.6Vcm. The demonstrated device offers the potential for compact sources with deterministic and ultra-high speed control of polarization states.