Optical near-field enhancement of metal-aperture VCSEL with nano metal particle

In this paper, we demonstrate the optical near-field enhancement of a metal-aperture GaAs VCSEL with a nanometer-size Au particle. We achieved a record near-field intensity estimated from far-field measurements. Also, we could avoid the polarization dependence of metal-aperture VCSELs by using a symmetric-shaped nano-particle in a metal aperture. Measurement results show that the optical near-field intensity is enhanced by localized surface plasmons excited at the metal particle. We estimated the optical power density to be 5.7 mW/μM² which is a record high value in near-field VCSELs and is even higher than that of conventional single-mode VCSELs. This enhancement may enable us to use nano-aperture VCSELs with further optimizations for high-density optical storage.