Patent ID: 7599267

Claim:
A writing method of writing information in an optical disk medium having not less than two data recording layers, comprising the steps of: writing a data pattern for power calibration in a first recording layer of the optical disk medium while a write power is changed in a stepwise manner; calculating a signal modulation depth and an asymmetry amount, which correspond to the write power, from a readout signal obtained by reading the data pattern; estimating a signal offset amount due to inter-layer interference from the recording layer other than the first recording layer by referring to previously stored standard data based on a relationship between the signal modulation depth and the asymmetry amount; calculating a signal modulation depth, in which the inter-layer interference is compensated, depending on the write power in consideration of the signal offset amount; and determining a write power for writing user data, based on the signal modulation depth, in which the inter-layer interference is compensated, depending on the write power.