Plasma dispersion effect based super-resolved imaging in silicon

In this paper we present a new method for shaping of a pulsed IR (λ=1550 nm) laser beam in silicon. The shaping is based on plasma dispersion effect (PDE). The shaping is done by a second pulsed pump laser beam at 532 nm which simultaneously and collinearly illuminates the silicon’s surface with the IR beam. Following the PDE, and in proportion to its spatial intensity distribution, the 532 nm laser beam shapes the point spread function (PSF) by controlling the lateral transmission of the IR probe beam. The use of this probe in laser scanning microscope allows imaging and wide range of contactless electrical measurements in silicon integrated circuits (IC) being under operation e.g. for failure analysis purposes. We propose this shaping method to overcome the diffraction resolution limit in silicon microscopy on and deep under the silicon surface depending on the wavelength of the pump laser and its temporal pulse width. This approach is similar to the stimulated emission depletion (STED) concept previously introduced in scanning fluorescence microscopy.