Near-field recording on phase-change nanoparticles and reflective reproduction from nanoantenna utilizing plasmonic resonance for high-density optical memory

Abstract

For high-density optical memory system, near-field recording on a medium with phase-change nanoparticles and dual metal layers was proposed. A finite difference time domain (FDTD) analysis demonstrated that a combination of a nanoantenna with such a medium so as to enhance plasmonic resonance would enable effective recording with larger (~10 times) working distance (WD) than for a conventional medium. A reproduction method of detecting the intensity of the reflected wave from the nanoantenna was also proposed in the same setup as the recording. We found that plasmonic resonance induced in the nanoantenna was enhanced and the intensity of reflected light was also increased when the phase state of nanoparticle was crystalline. Since the sub-diffraction limited size of nanoantenna is larger than a nanoparticle, the detected signal intensity can be greatly improved. Calculated results showed that our proposed system and methods for recording and reproduction would have a potential to become effective solutions for terabyte-class optical memory system.