<title>Use of near-field microscopy to analyze the field behavior inside a Fabry-Perot cavity: experiments and theory</title>

Abstract

The new born near field microscopy has already been used in many different topographic and spectroscopic investigations such as topography and spectroscopy. In this communication, we propose to exploit the capacity of a particular optical near field configuration, the so called Scanning Tunneling Optical Microscope (STOM), to scrutinize the field inside a Fabry-Perot cavity. This original analysis is possible due to the detection of evanescent fields by optical tunneling microscopes. In the proposed setup, we insert a STOM tip between the two mirrors of the resonant cavity. The tip is assumed to probe the field inside the resonant cavity. Beside the interest of mapping the standing waves in a cavity with a minimal perturbation, such a configuration allows one to imagine a new near field optical microscope working in dark field regime. Moreover, by setting the cavity in antiresonant mode, the evanescent field on the prism surface can be locally canceled. We will explain theoretically that the light density inside the prism is strongly attenuated since, in this case, the entrance face of the prism plays the role of a highly reflecting mirror. In such conditions, if the tip is brought sufficiently close to the object surface, the resulting coupling with the object will break the antiresonant regime allowing the light to enter the prism. We will show that this effect enhances the sensibility of optical tunneling microscopes. In this communication, we will describe the experimental setup and show the standing waves inside the Fabry-Perot and the first dark field images. These results will be compared with theoretical modelings based on a very precise self-consistent numerical method.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.