Development of ultrahigh densiti photon mode optical storage by nearfield optical technology

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Highly sensitive probe was fabricated for storage and readout. This was by the two-step chemical etching of a fiber to form a double-taperedsharpened core. By this, probe, efficiency of optical near-fieldgeneration and/or detection was improved more than 10 times. Derivative oiasobenzene, i.e., a sensitive photochromic material, was used for optical storage medium. Its thin film was coated on a slide glass by LB method Storage was carriedout by trans-cis transition by irradiating ultraviolet light (350nm wavelength) from an Ar laser. Typical time for storagee was 8 s when the powerdensity was 100 W/cm^2. Reas out was carried out by observing the local change of transmission due to this transition by using a near-field optical microscope. Diameter of a circularly stored pit was 50-100 nm, which was ten times smaller than that of a conventional storage. After the readout, the stored pit was erasec by irradiating a longer wavelengthlight, from which a reliable storage-readout-erassing was confirmed. More effeictive use of size-dependend locality of the optical near field was proposed for hither storage density. For this use, a method of high density deposition of a Latex sphere was developed, on which the LB film was coated Based on theoretical estimation for data transmission capcity, required high efficiency probe was fabricated To meed this requirement, surface plasmon mode was excited on the top of the probe tip by shapening the core in an assymetricmanner. As a result, efficiency of generating optical near-field was improved 10-100 times, from which data transmission rate higher them 100 Mbit//s was confirmed.