The optical disk device performs recording/reproducing of data by a predetermined recording block on the track of an optical disk. The device has a recording unit, an optical-head, and a failure detection unit. The recording unit generates a recording signal by modulating the data. The optical-head records data on the track by optical beam emission to the track according to the recording signal, and detects light reflected off the track and then generates a detection signal based on the reflected light. The failure detection unit detects an abnormal condition based on the detection signal changed from a normal condition. If the sum of duration of an abnormal condition in the recording block is equal to or greater than a first time-length, the failure detection unit determines that the recording block has a flaw.

The optical disk device performs recording/reproducing of data by a predetermined recording block on the track of an optical disk. The device has a recording unit, an optical-head, and a failure detection unit. The recording unit generates a recording signal by modulating the data. The optical-head records data on the track by optical beam emission to the track according to the recording signal, and detects light reflected off the track and then generates a detection signal based on the reflected light. The failure detection unit detects an abnormal condition based on the detection signal changed from a normal condition. If the sum of duration of an abnormal condition in the recording block is equal to or greater than a first time-length, the failure detection unit determines that the recording block has a flaw.

The optical disk device performs recording/reproducing of data by a predetermined recording block on the track of an optical disk. The device has a recording unit, an optical-head, and a failure detection unit. The recording unit generates a recording signal by modulating the data. The optical-head records data on the track by optical beam emission to the track according to the recording signal, and detects light reflected off the track and then generates a detection signal based on the reflected light. The failure detection unit detects an abnormal condition based on the detection signal changed from a normal condition. If the sum of duration of an abnormal condition in the recording block is equal to or greater than a first time-length, the failure detection unit determines that the recording block has a flaw.

The system includes a data storage medium comprising cells, an excitation circuit, and an emitter. The cells arranged in a three dimensional space. The excitation circuit excites each cell independently. Exciting a cell changes an optical property of the cell. The emitter emits a first beam onto a first cell during a first excitation period to orient electrical charges within the first cell to a first oriented value and intensity of electric field to a first intensity value. The emitter emits a second beam onto a second cell during a second excitation period to orient electrical charges within the second cell to a second oriented value and intensity of electric field to a second intensity value. The first and second cells maintain the first and the second oriented values and the first and second intensity values after the first and second excitation periods are over, respectively.

A method of writing data to a transparent substrate comprises forming a first voxel by focusing a first laser pulse on a first location in a transparent substrate; and forming a second voxel by focusing a second laser pulse on a second location in the transparent substrate. The first laser pulse and the second laser pulse have different amplitudes, resulting in the first and second voxels having different strengths. Also provided are a system useful for implementing the method; an optical data storage medium obtainable by the method; and a method of reading data from the optical data storage medium.

A recording medium according to the present disclosure includes a recording layer containing an organic compound having a non-linear optical absorption characteristic. The molar extinction coefficient of the organic compound against light having a wavelength of longer than or equal to 400 nm and shorter than or equal to 405 nm is greater than or equal to 90 mol.sup.1.Math.L.Math.cm.sup.1. In a transient absorption spectrum of the organic compound, an absorbance change Abs at a wavelength of longer than or equal to 400 nm and shorter than or equal to 405 nm is a positive value.

A method of writing data to a transparent substrate comprises forming a first voxel by focusing a first laser pulse on a first location in a transparent substrate; and forming a second voxel by focusing a second laser pulse on a second location in the transparent substrate. The first laser pulse and the second laser pulse have different amplitudes, resulting in the first and second voxels having different strengths. Also provided are a system useful for implementing the method; an optical data storage medium obtainable by the method; and a method of reading data from the optical data storage medium.