Reflective color filters using two-dimensional photonic crystals based on sub-wavelength gratings were proposed and constructed. Using low-cost nanoimprint lithography, an amorphous silicon layer was deposited through the low-temperature PECVD process and patterned into two-dimensional structures. The isolated amorphous silicon patterns were readily crystallized using a multi-shot excimer laser annealing at low energy. A study of the close relationship between color filter reflectance and silicon pattern crystallinity is introduced. Theoretical and experimental results show that the proposed color filters have high reflectance and, moreover, decrease the dependence on incident angle compared to one-dimensional photonic crystal color filters.

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We propose a gap servo method to reduce the overshoot in the near-field (NF) region. In general, we use a mode-switching servo which consists of approach, hand-over, and gap-control modes. However, there is a critical problem, such as an overshoot at the turning point from the approach mode to the hand-over mode, which may cause a collision between the SIL and the disk. In this paper, we propose an improved NF gap servo system using an exponential input in the approach mode which can reduce the overshoot and settling time of the mode-switching servo.Index Terms-Gap error signal (GES), mode-switching servo, near-field recording (NFR), overshoot.

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