| 摘要 |
An optical pickup comprises at least a semiconductor laser, a waveguide optically coupled with the semiconductor laser for propagating therein a light from the semiconductor to guide it to a recording medium and a light deflector element provided on the waveguide for deflecting the light propagated in the waveguide by means of a surface acoustic wave. A multi-mode oscillation laser capable of stably operating in longitudinal modes the number of which is not larger than 5 is used as the semiconductor laser. The semiconductor laser is disposed in proximity to the waveguide at a distance not larger than 1 mu m, thereby inputting the light from the semiconductor laser into the waveguide with a high efficiency. A frequency applied to the light deflector element may be changed upon change between a read-out state and a write-in state so that a light spot on the recording medium is held at a predetermined position (track or address). In the case where a grating is used as a light coupling element between the waveguide and the exterior thereof, a hologram grating is disposed in a path of the light derived through the light coupling grating from the waveguide to the exterior thereof so that a chromatic aberration produced at the light coupling grating due to a change in wavelength of the semiconductor laser is cancelled by that produced at the hologram grating.
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