This paper describes development of a bi-axial actuator-based air gap servo system for a near field optical recording system using a blue laser and a solid immersion lens (SIL). We first present a new pull-in procedure ensuring smooth air gap servo start-up without lens-disc collision. Furthermore, a memory-loop control technique has been employed to realize a high-speed air gap servo system guaranteeing a high data transfer rate.

Recent demonstrations have shown that near-field optical recording with a solid immersion lens in a conventional actuator is a strong candidate for optical storage beyond Blu-ray Disc. All results published so far were obtained with so-called first-surface configurations, in which the data layer is not protected by a cover-layer. In this paper we demonstrate a next step towards creating a system suitable for a commercial product with removable discs. First results are presented for read-out of discs with a few µm protective polymer cover-layer and a solid immersion lens with NA=1.45 and λ=405 nm.

We present a single-wavelength near field recording set-up with a blue laser and a NA=1.9 solid immersion lens in a conventional focus and tracking actuator. The most important aspects to realize such a near field recording system are discussed, in particular, gap error signal normalization and correction of chromatic aberration of the objective lens. First recording results demonstrate that the set-up is fully operational.

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