Near-field magnetooptic fiber probe

This thesis talks in detail about the development of a Near-Field Magneto-Optic Fiber Probe (NF-MOFP) to be used for the readback of ultrahigh-density magnetic recording. This NF-MOFP consists of a partially metallized tapered fiber (PMTF), similar to those used in near-field scanning optical microscopy (NSOM), but the subwavelength size aperture is coated with a reflective magneto-optic (MO) film. This device is then used in place of the PMTF in a polarization sensitive illumination/collection mode NSOM.;The MO properties, magnetic properties, and composition dependence on deposition parameters of GdCo, as deposited on glass wafers, were investigated and are discussed. A process was developed to deposit GdCo on the end of cleaved optical fibers and the PMTFs described above. An MO loop tracer was built to test the response of these devices to an applied field, and a system was built to image magnetic samples using the C-MOFPs.;The PMTF was modelled as a plane wave incident upon an aperture in an infinitely conductive sheet. Aspects of the emerging light such as intensity profile, decay of power away from the aperture and the power content in the various components were observed using this model. The temperature profile of the PMTF was modelled to predict how much light could be coupled into the NF-MOFP before the GdCo film reached its Curie point. This data was used in a model of the NF-MOFP and detection system in an attempt to predict how large a signal could be expected using this device.;A NSOM was built at CMU to investigate the optical properties of materials with a resolution below the diffraction limit. Each part of the NSOM is described in detail. The results of imaging a test sample are presented, along with the modelling of one NSOM imaging artifact that was present during this imaging. Two methods, etching and pulling, were used to form tapered fibers to be used in this NSOM. Sputtering, laser ablation and evaporation were used to metallize the tapered fibers to form the subwavelength aperture. These techniques are described, and the benefits of each method are discussed.