Bias-Magnet-Free Optical Isolating Ridge Waveguide Operating at 780 nm

Abstract

The fabrication and isolation characteristics of bias-magnet-free optical isolating waveguides with optimal wavelength operations of 780 nm are outlined in this report. Bismuth-substituted iron garnet thin films grown by liquid phase epitaxy on gadolinium gallium garnet substrates were used as the starting material to form the waveguides. Slab optical waveguides were produced using mechanical dicing and precision polishing. Single mode ridge waveguides were produced in the slabs using focused ion beam lithographic techniques. Commercially available polarizing fibers were implemented for the Faraday isolation function in place of polarizing films. Fiber-to-fiber isolation performance was measured to be up to 25 dB at 790 nm and fiber-to-fiber loss was as low as 11 dB at 765 nm, with the bulk of the loss being attributed to fiber coupling and connector losses. Intrinsic loss for the Faraday waveguide was estimated to be on order of 1 dB.