A Nano-aperture with l000X Power Throughput Enhancement for Very Small Aperture Laser System (VSAL)

摘要

Very Small Aperture Laser (VSAL) system is a near field optical data storage system that utilizes a nano-aperture fabricated at the front facet of a semiconductor laser to define a nano-sized spot and hence to achieve ultra-high density storage. However, these nano-apertures typically have very poor power throughput behavior when the sizes of the apertures are much smaller than the wavelength of the incident light. In this paper, we use numerical simulation tool XFDTD, which is a three-dimensional vector electro-magnetic field simulator based on the finite difference time domain (FDTD) method, to study the behavior of the nano-apertures. We show that for square apertures, the power throughput decays as r~4 (r is the size of the aperture) when the aperture size r is less than λ/4 (λ is the incident light wavelength). To solve the power throughput shortage problem, we present our novel nano-aperture design ―"C"-aperture. Compared with a conventional l00nm square aperture, the "C"-aperture provides l000X higher power throughput while maintaining a comparable near field spot size. We show that the greatly enhanced power throughput is due to both the polarization and resonance effects.