Design and experiments of a near-field optical disk head for very high efficiency

A high-density optical disk system with super parallel optical heads using a vertical cavity surface emitting laser (VCSEL) array is described for higher data transfer rate and technological capability. Optical heads of the VCSEL array and microlens array play key roles for obtaining higher evanescent light from small apertures with the optical disk, which is coated with lubricant and protective films on the flat surface in order to keep the gap between the super parallel optical head and the disk surface within 20 nm. Higher throughput efficiency has been obtained in the near-field semiconductor optical probe array head. However, the obtained evanescent light power is about 10 μW from a 100 nm probe aperture and 1 m W VCSEL power, which is still not enough to write a bit on the phase change optical disk. One solution to improve the optical power more than 10 times is to develop a special nanofabricated optical probe array of higher throughput efficiency. A metal fine grating fabrication method to get evanescent light wave resonant enhancement has been studied along with a 2-dimensional finite difference time domain simulation technique.