Multi-level optical storage in photochromic diarylethene optical disc

In this paper, a photon-mode multi-level optical storage method in photochromic diarylethene optical disc is firstly investigated to our knowledge. The reflectivity of photochromic materials varies nonlinearly with the exposure energy, which is used for multi-level optical storage. Eight-level optical storage of amplitude modulation is experimentally realized in a diarylethene optical disc. The 650 nm laser beam with power of 0.1 mW is used for recording and readout, and multi-level signals with high signal-to-noise ratio (SNR) are detected. Photochromic diarylethene molecules show the considerable potential to be used as multi-level optical disc storage medium. The recording density and data transfer rate can be significantly increased in multi-level optical storage system with coded modulation.