Fiber-embedded micro-Faraday rotator for the infrared

An infrared Faraday rotator embedded in a fiber is proposed and fabricated using Gd3−xBixFe5O12 single crystals; the specific bismuth substitution x was ∼0.9 in our experiments. Insertion losses for multimode and single-mode fibers are 2.9 and 4.3 dB at the 1.29-μm wavelength, respectively, and 4.3 and 6.7 dB at the 0.78-μm wavelength, respectively. It is shown that insertion losses would be decreased by increasing the bismuth substitution x. The fiber-embedded micro-Faraday rotator can be used in a fiber isolator not only for 1.3 μm but also for 0.8-μm wavelength regions.