109 Gbit/in.2 Recording on Near-Field Optical Disc Using Combination of Partial-Response Channel and Low-Density Parity-Check Code

The signal properties were examined at recording densities higher than 100 Gbit/in.2 in our solid immersion lens recording system of 1.84 numerical aperture (NA). The low-density parity-check coded partial-response (PR) 17-parity preserve/prohibit (PP) system increased the recording density by approximately 35% compared with the previous results. The recording power tolerance was ±8.1% at a recording density of 109 Gbit/in.2. We conclude that the upper limit of recording density is 109 Gbit/in.2, which is equivalent to 151 Gbytes for a 12-cm-diameter disc, assuming the same redundancy as that of the Blu-ray disc format.