INFORMATION PROCESSING DEVICE, OPTICAL DISC, INFORMATION PROCESSING METHOD, AND PROGRAM

There are provided an optical disk from which high-density data is reproduced and a reproduction apparatus that reproduces data from such an optical disk having high-density data recorded thereon. A photo-detecting section has two split detectors A and B in the direction of tracks on the disk. A signal processing section generates a TPP (Tangential Push-pull) signal made of a differential signal derived from detection signals from the detectors A and B, and further generates a reproduced signal by extracting from the TPP signal a high-frequency component signal in a record signal recorded on the disk. The disk is structured to have the record signal recorded on a carrier signal over the disk formed with a protruding and recessed pattern having a high frequency higher than or equal to a cut-off frequency. The signal processing section reconstitutes the high-frequency component signal in the record signal recorded on the disk by frequency-shifting the TPP signal obtained as a readout signal from a superimposed signal having the carrier signal and the record signal superimposed with each other.