Non-reciprocal devices using attenuated total reflection and thin film magnetic layered structures

There is need for non-reciprocal devices such as circulators and isolators. Although such devices are common at frequencies below 10 GHz, there is a lack of compact, low-weight, devices at higher microwave frequencies. This paper examines the non-reciprocal behavior associated with attenuated total reflection (ATR) for multi-layered dielectric and magnetic structures. Non-reciprocal behaviors produced by ATR have been explored for semi-infinite magnetic materials. This paper focuses on ATR behavior with magnetic films of finite thickness, from thick layers of around 3 cm to thin layers of about 1 mm. The results show significant non-reciprocity even for magnetic layers less than 0.1 cm thick, with reflection loss differences of more than 30 dB between positive and negative signal propagation. Results are presented for yttrium iron garnet and M type barium hexagonal ferrites. The two materials allow nonreciprocal behavior at different frequencies, 5-20 GHz for the garnet and 45-80 GHz for the hexagonal ferrite. (C) 2011 American Institute of Physics. [doi: 10.1063/1.3636365]