Magneto-optical Magnetic Field Sensors Based on Compact Magnetophotonic Crystals

In order to construct thin magneto-optical (MO) sensors, we have performed a theoretical study on the case of reflection-type one-dimensional magnetophotonic crystals (MPCs) including non-quarter wave dielectric layers and non-half wave magnetic defect layers. We could achieve single-, double-, and triple-cavity MPCs with thicknesses less than 1 μm. In this case, we obtained Kerr rotations around 30∘ accompanied by reflectivities greater than 40 %. Since the sensitivity of a MO sensor depends on the thickness of sensing film, these very thin MPCs can act as high sensitivity MO magnetic field sensors.