Highly efficient probe with a wedge-shaped metallic plate for high density near-field optical recording

Abstract

The distribution of the optical near-field generated by a probe with a wedge-shaped metallic plate was calculated using a finite difference time domain method. The dependence of the distribution on the size and the material of the metallic plate was calculated, and it was shown that a strong optical near-field was generated at the apex of the metallic plate when the size and the material were optimized so that a surface plasmon was excited in the metallic plate. The influence of the recording medium was also calculated. The resonance wavelength shifted toward a longer wavelength and the decay length of the optical near-field increased when the recording medium was placed near the probe. The spot size calculated on the surface of the recording medium was 30 nm, and the efficiency (defined as the ratio between the power of the optical near-field at the surface of the recording medium and that of the incident light) was about 20% when the spacing between the probe and the recording medium was 10 nm. The near-field distribution for a probe with two metallic plates was also calculated, and it was shown that a strong optical near-field was generated between the apices of the metallic plates when the plasmon was excited in the metallic plates.

Imaging Ultrafast Demagnetization Dynamics after a Spatially Localized Optical Excitation

“…Necessary to this end, it is required to deliver the optical energy to a sub-100-nm spot size, i.e., far beyond the diffraction limit of optical light. The most successful approaches include localization of the evanescent light from near-field optical probes [13], using metallic plates to excite surface plasmons [14,15] or a combination thereof [16].Here, we implement time-resolved Fourier transform holography (FTH) [17] and exploit x-ray magnetic circular dichroism (XMCD) to directly image the magnetization dynamics induced by a deliberately spatially localized excitation via an optical standing wave. In addition to a spatially confined reduction of the magnetization and its subsequent slower recovery, evidence is found for concurrent changes in the spatial magnetization profile, suggesting the presence of ultrafast lateral transport of spin-polarized electrons on a nanometer length scale.…”

“…Necessary to this end, it is required to deliver the optical energy to a sub-100-nm spot size, i.e., far beyond the diffraction limit of optical light. The most successful approaches include localization of the evanescent light from near-field optical probes [13], using metallic plates to excite surface plasmons [14,15] or a combination thereof [16].…”

Double Layered Electrode for Plasmon Antenna

“…Au and Ag for the plasmon antenna showed a high intensity for generating near field optics 7) . However, when these materials are used as a plasmon antenna in the NOAH head as shown in Fig.1, their durability becomes a problem, such as in the adhesion between Au and glass, and in the oxidation of Ag.…”

“…In addition, Matsumoto et al reported the simulation results that resonance wavelength depends on the shape of the plasmon antenna and its materials 7) .…”

Thermally assisted magnetic recording on a bit-patterned medium by using a near-field optical head with a beaked metallic plate

“…We previously proposed an optical near-field generator with a beaked metallic plate ͑called a "nanobeak"͒. 11,12 Marks with a diameter of 40 nm were written on a phase-change recording medium by a head with the nanobeak. In the present work, we performed a writing experiment in which we used the nanobeak to write marks on a BPM.…”