Waveguide optical isolator based on Mach–Zehnder interferometer

TLDR

Ridge waveguides are fabricated in a Mach–Zehnder configuration on a single film of bismuth‑, lutetium‑, neodymium‑iron garnet, enabling nonreciprocal interference without the need for polarizers. The isolator achieves a 19 dB extinction ratio at 1.54 µm and exhibits flat wavelength dependence within 2 dB across the 1.49–1.57 µm range.

Abstract

A waveguide optical isolator based on nonreciprocal interference is demonstrated. Ridge waveguides are fabricated in a Mach–Zehnder configuration on a single film of bismuth-, lutetium-, neodymium-iron garnet. With this design, no polarizers are required to achieve extinction in the backward propagation direction. This isolator exhibits a 19 dB extinction ratio at λ=1.54 μm. A flat wavelength dependence, to within 2 dB, has been observed in the range between 1.49 and 1.57 μm.