An optical pickup of an optical disc apparatus has a lens holder for holding an objective lens is pivoted with a guide shaft slidably in a direction in parallel with an optical axis of the objective lens and rotatably around the guide shaft in a direction perpendicular to the optical axis. For focusing a laser beam on a data recording face of an optical disc in a focusing on operation, a wobble signal of rectangular waveform having a predetermined voltage and a predetermined frequency is applied to a tracking coil for reciprocally displacing the lens holder in the direction perpendicular to the optical axis, while a focusing coil is driven for moving the lens holder in the direction in parallel with the optical axis. Thus, the lens holder can be moved smoothly along the guide shaft, so that the possibility of failure of the focusing the laser beam on the optical disc can be reduced drastically.


> Two-photon absorption generated carrier lifetime reduction in semiconductor waveguide for semiconductor based raman laser and amplifier

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