OPTICAL DATA STORAGE USING A SOLID IMMERSION LENS

Abstract

A near-field optical technique, using a new type of Solid Immersion Lens (SIL), has been developed and applied to the writing and reading of domains in a magneto-optic material. The SIL is a truncated glass sphere which serves to increase the numerical aperture of the optical system by n2, where n is the index of refraction of the lens material. By mounting a 1 mm SIL on a slider, we have been able to fly the SIL on a magneto-optical disk. We have demonstrated writing and reading with such a lens at data rates exceeding 1 Mbit/s with a carrier-to-noise ratio of approximately 50 dB. Using a 830 nm laser and a n = 1.5 SIL, the focused spot size was reduced by close to a factor of 2 and was measured to be 600 nm.