| 摘要 |
A vertical cavity surface emitting laser (VCSEL) device with an integral photodetector structure has improved intensity control characteristics. A laser optical source of the VCSEL emits light upward through a cavity formed in an upper electrode. A monitoring photodetector is formed below the laser optical source to receive light transmitted from the source downward. The intensity of the light transmitted downward from the optical source is proportional to the intensity of the light emitted upward through the cavity. Thus the detection signal provided by the photodetector sensing the downward transmitted light may be used for precise control of the driving voltage applied to the optical source. Because to the proportionality between the upward and downward emitted light, this control arrangement allows for improved control of emitted intensity of the VCSEL. An optical pickup apparatus adopting the improved VCSEL is also disclosed. For the optical pickup device, the VCSEL is enclosed in a housing having a window for allowing transmission of emitted light from the VCSEL without alteration of the direction of propagation. An optical converging means (a lens) focusses the emitted light onto an optical recording medium, which reflects the light back to the housing via the lens. When the light reflected from the recording medium passes back through the window, the optical path of the reflected light is changes so as to cause the light to impinge upon a photodetector. The window may be embodied as a hologram device.
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