Optical information recording medium, method of manufacturing same, and recording method

Abstract

Provided are an optical information recording medium and its recording method capable of appropriately recording with a high density and at a high speed by using a recording wavelength in the range from 360 to 450 nm and especially about 400 nm (such as 405 nm). A preferable push-pull signal by performing recording based on the Low to High method instead of the conventional High to Low method and setting the pit reflectance higher than the reflectance of the non-pit region, the maximum film thickness of the recording layer in the track region where pits are arranged in the range from 25 to 60 nm, and the maximum film thickness of the recording layer in the region adjacent to the track in the range from 5 to 30 nm. Moreover, it is preferable that the film thickness of the reflection layer be in the range from 120 to 180 nm and the groove width of the reflection layer be in the range from 85 to 150 nm.

Description

technical field [0001] The present invention relates to a write-once optical information recording medium and a recording method thereof, in particular to an optical information recording medium and a manufacturing method thereof for recording with laser light (blue laser, blue laser) with a wavelength of 360 to 450 nm generated by a semiconductor laser and recording method. Background technique [0002] Currently, a write-once optical information recording medium using blue laser light near 360-450 nm (for example, about 405 nm) on the short-wave side has been developed (see Patent Document 1: Japanese Unexamined Patent Application Publication No. 11-120594). [0003] The optical information recording medium uses an organic pigment compound on the optical recording layer. The organic pigment compound is decomposed or modified by absorbing laser light. As a modulation degree, the optical characteristic of the laser light in the recording and reproduction wavelength is change...

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Problems solved by technology

[0016] However, recording media using blue lasers require high-density recording, and the physical channel pitch is narrow, and the heat generated during pigment decomposition tends to be transferred to adjacent channels, resulting in deterioration of characteristics.

[0017] In addition, although the development of the optical information recording medium by the Low to High method has also been carried out recently, in the blue laser wavelength region, the groove becomes a concave direction with respect to the incidence of the laser beam, and a 0.1 mm light-transmitting layer is provided on the laser beam. In the case of an optical information recording medium on the incident surface, if a pigment of a type whose reflectance changes with the imaginary part k of the complex refractive index before and after recording as the main factor is used, then in the optical information recording by the Low to High method media, causing the push-pull (NPPb) signal to become too high when not recording

[0018] If the push-pull (NPPb) signal becomes too high, in the focus method by the astigmatism method, there is difficulty in distinguishing light and dark of the photodetector, and focus follow-up cannot be performed, or even in the DPP (differential push-pull) method , it is also difficult to identify the light and dark of the photoelectric detector, and it is impossible to follow the tracking and other problems

In addition, it is necessary to use an organic pigment with a large extinction coefficient in the background, and the push-pull value is easily increased due to the groove depth and width of the groove

Also, in this case, since the refractive index is slightly small, push-pull tends to be good, but since it is a pigment with a large extinction coefficient, reflection is likely to occur. good push-pull values ​​for the disc

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