Wideband acousto-optic modulator/isolator in integrated photonics

An optical isolator comprising:

• a first spatial mode multiplexer;
• a first nonreciprocal spatial mode beamsplitter including at least one first interdigitated transducer (IDT) and a first optomechanical waveguide, the at least one first IDT mechanically coupled to the first optomechanical waveguide, and the first optomechanical waveguide optically coupled to the first spatial mode multiplexer;
• a dispersion balanced delay line optically coupled to the first nonreciprocal spatial mode beamsplitter, the dispersion balanced delay line adapted to minimize dispersion between light in first and second spatial optical modes;
• a second nonreciprocal spatial mode beamsplitter including at least one second IDT and a second optomechanical waveguide, the at least one second IDT mechanically coupled to the second optomechanical waveguide, and the second optomechanical waveguide optically coupled to the dispersion balanced delay line;
• and
• a second spatial mode multiplexer optically coupled to the second nonreciprocal spatial mode beamsplitter;
• wherein each of the at least one first and second IDTs is adapted to generate phonons and to direct the phonons in a corresponding phonon-launch direction toward a corresponding one of the first and second optomechanical waveguides, the phonons adapted to cause interband coupling between the first and second spatial optical modes for light in a corresponding one of the first and second optomechanical waveguides, the corresponding phonon-launch direction of each of the at least one first and second IDTs being non-perpendicular to a corresponding one of the first and second optomechanical waveguides.