Optical disc writing strategy for analog signal recording

Optical discs are being sought as low-cost, earth-friendly storage candidates in response to increasing data volumes. To increase the recording density of optical disc, analog recording technique such as the Orthogonal Frequency Division Multiplexing (OFDM) method has been investigated. Since bitwise information is recorded on optical discs, it is necessary to create a column of marks corresponding to the analog signal for the OFDM method. The Delta-Sigma Modulation (DSM) is known as an analog to digital conversion method in the area of audio. This method transfers efficiently an analog signal to a binary sequence with a simple circuit. In this paper, the application of the method for analog signal recording and the simulation results of the mark recording process on the optical disc are described. The optical disc recording utilizes temperature rise of a multilayer film stack in recording process that is triggered by light focusing. A simplified, 2.5-dimension, thermal analysis is applied to do the large-scale simulation of recording mark sequence.