Analysis and fabrication of microaperture GaAs-GaAlAs surface-emitting laser for near-field optical data storage

We have proposed a microaperture vertical cavity surface-emitting laser (VCSEL) for use in near-field optical data storage. We carried out the near-field analysis of microaperture VCSEL using two-dimensional (2-D) finite element method. We calculated the distribution of optical near-field generated near a microaperture, and showed that the spot size is potentially smaller than 100 nm, which is less than wavelength by a factor of 8. We fabricated a VCSEL loaded by an Au film on the top surface for blocking the emitting light and formed a subwavelength-size aperture using focused ion beam (FIB) etch through this film. Single-mode operation was obtained for a microaperture VCSEL with 3-μm square active region. The differential quantum efficiency was increased by a factor of 3 in comparison with that before forming a 400-nm square aperture. We estimated the power density of light radiated from a 400-nm square aperture to be 0.17 mW/μm². In addition, we measured the near-field distribution of a 200-nm square aperture VCSEL by using a scanning near-field microscope