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Near‐field optical microscopy simulations using graphics processing units

Scanning near‐field optical microscopy (NSOM) is a perspective method for local analysis of optical parameters of nanostructures used in electro‐optics, photonics and many other field of research. Due to complicated nature of topography‐related effects in the optical signal, which can influence or completely alter the NSOM data, the practical use of this method for quantitative analysis is still limited. One of the approaches to determine the effects of topography on optical data is to simulate NSOM images using an electromagnetic field modeling method, e.g. finite difference in time domain method. However, this approach is extremely slow, as full electromagnetic field propagation calculation must be run for each pixel of the resulting simulated image. In this paper, we present a fast method for computing simulated NSOM images based on the use of a graphics processing unit (GPU or computer graphics card) in order to speed up the computations. We will show that the large speedup using this approach (more than 40 times) allows us to simulate images in a time comparable to their real measurement, which increases the possibilities of quantitative analysis using NSOM. Data simulated by a GPU will be compared with those of real measurements as well. Copyright © 2010 John Wiley & Sons, Ltd.