In this study, the mechanism of resist pattern collapse during the resist development process is investigated. Resist pattern collapse occurs while the rinse liquid is being dried off. This conclusion was reached after observing the resist pattern before and after the rinse-liquid drying process. The resist pattern in the rinse liquid was observed using an atomic force microscope. The source of resist pattern collapse is the surface tension of the rinse liquid. The force increases with decreasing space width between resist patterns. To avoid the resist pattern collapse problem, the use of a low-surface-tension rinse liquid, a rinse liquid with contact angle ∼90° at the resist surface, or a rigid and highly adhesive resist material is effective.

A technique for recording and retrieving small marks beyond the optical diffraction limit was proposed. The basic experiment with this technique was also carried out at a constant linear velocity of 2.0 m/s, rotating a disk with a multi-layered structure of Sb and GeSbTe, which were separated by a thin film of SiN. By use of the optically nonlinear property of the Sb thin film, carrier to noise ratio of more than 10 dB was obtained from recorded marks of 90 nm, using an optical system with the laser wavelength of 686 nm and a numerical aperture of 0.6.

We demonstrate a new near-field technology that uses a metallic probe in an optical disk. The metallic probe is produced in a focused spot on a readout layer composed of silver oxide. However the metallic probe is not transparent to far-field light, near-field light generated around it. Therefore, a mark of less than 100 nm in length could be recorded and reproduced by detecting the scattered light around the metallic probe and the mark.

A proposal for a photonic transistor is made and some basic proving experiments are described. These experiments show that by focusing two laser beams (405 and 635 nm) in one small spot on a high-speed rotating optical disk, a large signal enhancement is observed. It was found that a plasmon interaction generated between a silver light-scattering center and recorded small marks in the optical disk with a super-resolution near-field structure produced the large signal amplification in the spot (<1 μm). A modulated signal of the blue laser was enhanced by 60 times by controlling the red laser power from 1.5 to 3.5 mW. It has been shown that the system has the potential to realize all-thin-films photonic transistors by using local plasmon amplification.

We present results of reactively sputtered silver oxide thin films as a substrate material for surface-enhanced Raman spectroscopy (SERS). Herein, we show that deposited layers develop an increasingly strong SERS activity upon photoactivation at 488 nm. A benzoic acid/2-propanol solution was used to demonstrate that the bonding of molecules to SERS active sites at the surface can be followed by investigating temporal changes of the corresponding Raman intensities. Furthermore, the laser-induced structural changes in the silver oxide layers lead to a fluctuating SERS activity at high laser intensities which also affects the spectral features of amorphous carbon impurities.