Spectral resolution of optical filters based on diffractive optical elements with non-uniform illumination

We study the transmission coefficient and the spectral resolution of optical filters based on a diffractive optical element (DOE), with a collimating lens, input and output fibers. We limit our study to filters that can be analyzed with a scalar (i.e., Fourier-optical) formalism, and specify requirements that the filter geometry has to satisfy for this formalism to give an accurate description. Finally, we study the trade-off between power loss and spectral resolution in DOE-based filters

Characterization of Oxidation-Induced Stacking Fault Rings in Cz Silicon: Photoluminescence Imaging and Visual Inspection After Wright etch

AbstractOxidation-induced stacking fault rings in polished Cz silicon samples before and after thermal wet oxidation are investigated by use of photoluminescence imaging. Currently the standard procedure for OSF ring detection is to expose the samples to a toxic preferential etchant, e.g. a Wright solution, after a thermal oxidation. This solution primarily attacks the regions with stacking faults, allowing detection by visual inspection. Samples from the seed end of p-type Cz silicon ingots with resistivities of approximately 1Ohm-cm were measured by PL imaging before and after a thermal oxidation process. Subsequently, Wright-etching was performed on the oxidized samples to expose stacking faults. The lifetime variations in the PL images were correlated with the location of the rings in the preferentially etched surfaces, and good agreement was found. The results show that for this crystal pulling process, even the PL images of unpassivated polished samples can be used to detect the OSF ring location. The thermal oxidation at 1100°C enhanced the contrast between the OSF ring and the rest of the sample in the PL image