![]() The device shows a maximum isolation of 17.9 dB at a wavelength of 1561.7 nm, although it requires an out-of-plane magnetic field to orient the magnetization of the garnet. For example, a TE-mode Mach-Zehnder Interferometer (MZI) isolator was fabricated in a Si:H waveguide with a Ce:YIG garnet bonded on one sidewall. 17 A TE-mode NRPS can also be produced by placing a magneto-optical cladding on one side of a waveguide. A nonreciprocal TE-mode isolator based on the approach was theoretically analyzed 16 and later experimentally demonstrated. One approach to create such in-plane (IP) asymmetry is to use a magneto-optical rib waveguide made of a garnet with an out-of-plane (OP) easy axis of magnetization, where a domain wall is placed at the center of the rib. To achieve TE mode isolators without polarization rotators, 9,14,15 the magneto-optical material must be incorporated into a horizontally asymmetric waveguide structure to generate a NRPS. ![]() 13 As most semiconductor lasers emit into the transverse electric (TE) mode, TE mode isolators are essential for many applications. However, the vast majority of the waveguide magneto-optical isolators reported so far operate only for the transverse magnetic (TM) polarization. 2,10–12 Recent advances have led to waveguide optical isolators with performances approaching that of bulk optical isolators, 11,12 qualifying them as viable isolation solutions for PIC applications. 3 The optical isolator structure based on magneto-optical nonreciprocal phase shift (NRPS) effects was demonstrated using epitaxial Ce:YIG films as the guiding layer, 4 by bonding epitaxial Ce:YIG films onto semiconductor waveguides 5–9 or by monolithically depositing polycrystalline Ce:YIG with YIG seed layers on silicon photonic devices. At the telecommunication wavelengths, cerium doped yttrium iron garnet (Ce:YIG) is one of the best magneto-optical (MO) materials because of its large magneto-optical activity and low optical loss, which produces an exceptional magneto-optical figure of merit (FOM, defined as the ratio of Faraday rotation (FR) to optical loss). Optical isolation can be achieved by breaking the time-reversal symmetry of light propagation using nonreciprocal properties of magneto-optical materials. 1,2 Optical isolators allow one-way transmission of light, protecting sensitive components such as lasers and amplifiers from harmful reflections. Integrated optical isolators or circulators are essential components of photonic integrated circuits (PICs) and optical communication systems.
0 Comments
Leave a Reply. |