Multi-level read-only recording using signal waveform modulation

A novel multi-level read-only recording using signal waveform modulation (SWM) is presented. The SWM is realized by inserting a sub-pit/sub-land to the original land/pit. Numerical simulation provides a helpful tool for the write strategy optimization. This method is experimentally validated on the DVD platform. Comparing with 2-level recording, an increase of 50% in capacity can be expected. It shows superiority over signal amplitude modulation (SAM) multi-level in replication processing, capacity increase and servo performance.