Thin-film magnetless Faraday rotators for compact heterogeneous integrated optical isolators

This report describes the fabrication, characterization, and transfer of ultra-compact thin-film magnetless Faraday rotators to silicon photonic substrates. Thin films of magnetization latching bismuth-substituted rare-earth iron garnets were produced from commercially available materials by mechanical lapping, dice polishing, and crystal-ion-slicing. Eleven-mu m-thick films were shown to retain the 45 degrees Faraday rotation of the bulk material to within 2 degrees at 1.55 mu m wavelength without repoling. Anti-reflection coated films evince 0: 09 dB insertion loses and better than -20 dB extinction ratios. Lower extinction ratios than the bulk are ascribed to multimode propagation. Significantly larger extinction ratios are predicted for single-mode waveguides. Faraday rotation, extinction ratios, and insertion loss tests on He-ion implanted slab waveguides of the same material yielded similar results. The work culminated with bond alignment and transfer of 7 mu m-thick crystal-ion-sliced 50 x 480 mu m(2) films onto silicon photonic substrates. Published by AIP Publishing.