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The work includes theoretical analysis of heat-up of an optical near-field probe with laser radiation passing through it. Stationary solution is found regarding the probe heating due to partial absorption of the radiation by the metal film and linear heat exchange between the probe and its environment. Temperature space distribution down the tapered part of the probe is found. The threshold power of continuous radiation leading to melting of the probe is estimated. INTRODUCTiONNear-field optical microscopes (NFSOM) have been undergoing intensive development the last ar1 . NFSOM can be used not only for imaging and spectroscopic purposes but also for providing superlocal force action of light on a sample. NFSOM probe is the key element defining the maximum power that can be delivered to the sample surface and structure of nearfield radiation acting on the sample. That is why consideration of the probe heating by laser radiation passing through it becomes important if marginal parameters of superlocal light action are to be found. As input light power increases, heating of the probe leads to deformation of the probe followed by damage, limiting the maximum applicable light power. SETTING OF THE PROBLEM.NFSOM fiber probes are usually formed by stretching or chemical etching of an optical fiber. Such probes generally have intricate shape, hut as a first approximation assume that probe consists of two parts (Fig. 1). One part (denoted II in Fig.l) is a half-closed cylinder of diameter d and the other part (I) represents a cone with the element angle y. The cone is bounded with two radii r0 and r1. The cone part of probe is cladded with a thin metal film.128 / SPIE Vol. 2384 0-8194-173 1-9/95/$6.00 Downloaded From: http://proceedings.spiedigitallibrary.org/ on 06/27/2016 Terms of Use: http://spiedigitallibrary.org/ss/TermsOfUse.aspx

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