We propose a method for recording a multilevel signal onto optical read-only-memory discs. In this method we use signal processing to generate a multilevel recording signal that satisfies the zero-intersymbol interference condition and the zero-dc condition. The resultant multilevel signal is emboss recorded as the position displacement of groove walls. To play back a disc, push–pull detection and an adaptive equalizer are used. We also introduce feedback to reduce the nonlinear characteristics existing in the recording and playback systems. An experimental disc with 0.6-μm track pitch and 0.28-μm/bit density is made. When a digital versatile disc equivalent optical pickup is used to play back this disc, we confirm that a two-dimensional eye pattern of 16 levels is clearly observed.
© 2000 Optical Society of America
Seiji Kobayashi, Toshihiro Horigome, and Hisayuki Yamatsu, "Signal Processing and a Groove Baseband Recording Method to Achieve a High-Density Optical Disc," Appl. Opt. 39, 6019-6027 (2000)