Effect of elliptical Gaussian beam in solid-immersion-lens-based near-field recording optics

In this study, we summarized the characteristics of beam spot profiles, exit pupil images, the gap error signal and the push-pull signal obtained when using a Gaussian beam in solid immersion lens (SIL) based near-field recording (NFR) optics. As the rim intensity of the Gaussian beam decreases and the tracking direction shift of the SIL assembly increases, the intensity of the beam spot is decreases. The exit pupil image is distorted asymmetrically by the tracking direction shift of the SIL assembly. We confirmed that the tracking direction shift of the SIL assembly affects the gap error signal and push-pull signal. When using linearly polarized incident light, it is observed that a tracking direction shift of 500 μm induces a gap error signal reduction of 3.2%. The push-pull signal is offset by 18.7% in the case of a tracking direction shift of when the tracking direction is shifted by 20 μm.