Sputtered-magnet Mach-Zehnder waveguide isolator

The development of a workable optical integrated isolator for use in photonic integrated circuits is increasingly important due to the rapid growth in fiber optical systems. No fully integrated isolator has been demonstrated as yet. The device that we propose here addresses a number of unresolved problems. Its Mach-Zehnder design eliminates the need for input and output polarizers present in conventional isolators; integration of the polarizers has been one the main stumbling blocks to achieving a fully integrated device. Low insertion losses are obtained using a vertically tapered Y-branch, recently demonstrated in our laboratories. The arms of the Mach-Zehnder interferometer are magnetized in opposite directions with a patterned thin-film magnet.