| 摘要 |
A reflection-type optical recording medium has, on a surface thereof on which track guide grooves are formed, a layer of a recording material which has an increased energy reflection coefficient at a write portion upon data write therein. The track guide grooves are formed such that a depth .PHI.0 thereof given by: .PHI.0 = 2?n?d/.lambda.?2? (where n is a refractive index of the medium which covers the track guide grooves and which transmits input/output read light therethrough, d is an actual step of said track guide grooves, and .lambda. is a wavelength of the read light) satisfies: (i) sin.PHI.0 < 0 for .theta.2 - .theta.1 > 0, and (ii) sin.PHI.0 > 0 for .theta.2 - .theta.1 < 0 where .theta.1 and .theta.2 are, respectively, phases of reflected read light before and after data write to the recording material which are defined by: r1 = R1?expi.theta.1 r2 = R2?expi.theta.2 R1 < R2 (where r1 and R1 are complex reflection coefficients before data write to the recording material, and r2 and R2 are absolute values of the complex reflection coefficients after data write to the recording material.) High-speed data write is possible while read signals of high S/N ratio are obtained. |
