Summary of Research Project Results under JSPS FY2001
"Research for the Future Program"

1.Research Institution Tokai University
2. University-Industry Cooperative Research Committee
 130th Committee on Opto-electronics
3.Term of Project FY 1997 〜 FY 2001
4.Project Number 97R13001
5.Title of Project Ultimate Information Proceeding Devices and Systems Using High-Functional Spatial Light Modulation Method

6.Project Leader
Name Institution,Department Title of Position
Kenya Goto Tokai University , School of High Technology for Human Welfare Professor

7.Core Members

Names Institution,Department Title of Position
Fumio Koyama Tokyo Institute of Technology, Precision and Intelligence Laboratory Professor
Jyunichi Takahara Osaka University, Faculty of Engineering Science Assistant Professor

8.Summary of Research Results

Near-field semiconductor probe arrays with very high throughput efficiency had been developed in this project. This was done by developing nano-fabrication processes with self-alignment technology between the focal points of the micro-lens array fabricated on the probe substrate and the nano apertures of the near-field optical probe array on the same substrates, which had been developed in this project using special photo-resist layers that consist of an UV sensitive photo-resist and a special IR sensitive emulsion. One of the reasons why the throughput efficiency of this array on the semiconductor substrate is more than thousand times as high as compared to the conventional probes is the success of fabrication processing for the micro-lens array on a single crystal semiconductor thin wafer. The self-alignment technology in this project can cause the laser beam to focus within just inside of the near-field semiconductor probe with the accuracy of 10 nano meter between optical axe and center of the aperture. As there is no loss from the output windows to the flat top aperture tip of the near-field optical probes, the conversion efficiency between the far-field light to the near-field light which can be observed just outside of the aperture of the probes is depended on the far-field beam waist size vs. evanescent wave aperture size. Finally we could get more than 10 % throughput efficiency for the case of 100 nm aperture sizes. In the case of the near-field arrayed apertures located periodically on the surface of the metal film or dielectric material mutual interaction between the evanescent lights emitted from each aperture emphasis each other the evanescent light intensity. This may be occurred by owing to the surface plasmon polariton effect. More appropriate aperture distance and location distribution will make the enhancement stronger with the improvement of the fabrication process for the aperture array. Beside the great improvement of the probe array for the writing bits on the surface of the disk a novel signal detection method from the super high density optical written disk surface was also improved by using the same VCSEL array optical head which has both the micro-lenses and periodically positioned optical apertures. The VCSEL impedance between the two electrodes of the each VCSEL element changes with the reflected feed back light from the disk. This can be a very good new signal detection method in a higher density optical phase change disk. The simulation of in both the probe array and the signal detection analysis were performed using improved time domain finite differentiation (FDTD) method which had been published by us. Two dimensional optical head will lead very high data transfer rate in the optical disk in near future.

9.Key Words

(1)near-field semiconductor probe、(2)throughput efficiency、(3)nano-fabrication process
(4)self-alignment、(5)micro-lens array、(6)nano aperture
(7)surface plasmon polariton、(8)VCSEL array、(9)feedback light induced VCSEL impedance