Abstract

In order to increase the recording density in optical disks, it is effective to adopt mark-edge recording with a short-wavelength laser. A powerful visible lasing light as short as 670 nm is now available using a InGaAlP diode ¹⁾. The power of the laser, however, includes too much noise to be used in a high density optical disk system. In mark-edge recording, still more distorted marks induce more bit error than in conventional pit position recording. It is, therefore, indispensable to precisely control the laser power level in mark-edge recording. The authors have developed a new optical head and a new fast laser power control electro-optics which reduces much of the laser noise, and, at the same time, rapidly controls the laser power enough to follow the reference laser power signals. In an experiment using this technique, the laser noise decreased by 10 dB and RIN could be reduced to–126 dB/Hz at 10 MHz without a high frequency superimposition. Mark shapes were obtained by simulation based on thermal analysis.

© 1991 Optical Society of America