Fast-laser-power control for high-density optical disk systems

An optical head and a fast laser power control electro-optics using short wavelength laser diode was developed. This laser power control method reduces much of the laser noise, and, at the same time, rapidly regulate the laser power in order to compensate for mark shape. The relative intensity noise of the laser, lasing at 670 nm, was reduced -127 dB/Hz. This noise level is enough low to use the short wavelength laser diode for high density recording. This method is able to set various writing power waveforms to avoid mark distortion. The recorded mark shapes were got in case of (1,7) mark edge modulation, the minimum mark length is 0.8 micrometers . This high recording density is equivalent to 1.7 bit/micrometers .