The transmission characteristics of silver–dielectric superlenses in photolithographic applications are studied here and are shown to introduce significant spatial frequency-specific artifacts into images of subwavelength patterns when the superlens is below a certain thickness. These artifacts have a negative impact on the fidelity of patterns produced by photoresists exposed through superlenses, which is not ideal in photolithography applications. The cause of the artifacts is identified as a mismatch between the dc transmission coefficient and the peak transmission coefficient of the superlens, which is normally placed beyond the conventional diffraction limit. We show that this mismatch can be corrected by increasing the thickness of the component layers within the superlens, with the result that the total transmission through the superlens is reduced but the range of spatial frequencies that can be transmitted without severe distortion is increased. Analyses and examples are presented for superlens designs that maximize the spatial frequency bandwidth over which good imaging can be expected; systems with a total thickness of 120–140 nm are optimal, delivering superresolution imaging over spatial frequency bandwidths of up to .
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Ciaran P. Moore, Matthew D. Arnold, Philip J. Bones, and Richard J. Blaikie
J. Opt. Soc. Am. A 25(4) 911-918 (2008)
Ciaran P. Moore, Richard J. Blaikie, and Matthew D. Arnold
Opt. Express 17(16) 14260-14269 (2009)
Adv. Opt. Photon. 1(3) 484-588 (2009)