Abstract: A recording apparatus, which records information in an optical recording medium, includes: a mode-lock laser unit including a saturable absorber section that applies a bias voltage, a gain section that feeds a gain current, a semiconductor laser that emits laser light used to record the information on the optical recording medium, and an external resonator; an optical modulation unit performing amplification modulation on the laser light emitted from the mode-lock laser unit; a reference signal generation unit generating a master clock signal and supplying a signal synchronized with the master clock signal to the gain section of the semiconductor laser; a recording signal generation unit generating a recoding signal based on the master clock signal; and a driving circuit generating a driving pulse used to drive the optical modulation unit based on the recording signal.

Abstract: The present invention provides a method and an apparatus for determining the number of data layers in an optical disc. Firstly, the objective lens of the optical pickup head is controlled so that it moves toward the optical disc. At the same time, a generated SBAD signal is recorded. The number of wave peaks in the SBAD signal is then detected and the number of the data layers in an optical disc is determined according to the detected number of wave peaks in the SBAD signal.