An analog MOS circuit that imitates bursting properties of spiking neurons is proposed and fabricated. The circuit consists of the Oregonator device that can easily be implemented on analog CMOS LSIs. We demonstrate temporal properties of the proposed circuits by SPICE and fabricated ICs.
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. The far-field output power from the nano-aperture was increased by a factor of 1.8 by inserting an Au nano-particle. The optical near-field was localized with a near-field power density of 5.7mW/µm2 and a spot size of 280nm. Also, we could avoid the polarization dependence of metal-aperture VCSELs by using a symmetric-shaped nano-particle in a metal aperture. This significant improvement may enable us to use the nano-aperture VCSEL for high-density optical storages.
We present the fabrication and characterization of a novel distributed Bragg reflector consisting of a grating loaded slab hollow waveguide. In this structure, we are able to obtain a high reflectivity even by using thin and short surface gratings because of the large contrast in refractive indices between a grating material and an air-core. We fabricated a slab hollow waveguide Bragg reflector with 620µm long, 190nm deep 1st-order circular grating composed of SiO2 exhibiting strong Bragg reflection at 1558nm with an air-core thickness of 10µm for TM mode. The peak reflectivity is 65% including fiber coupling loss, the 3dB bandwidth is 2.8nm and the grating-induced loss is less than 0.5dB.