Grating imaging scanning lithography

We present a grating imaging scanning lithography system for the fabrication of large-sized gratings. In this technology, ±1-order diffractive beams are generated by a phase grating and selected by a spatial filter. Meanwhile, a 4f system enables the ±1-order diffractive beams to form a grating image with a clear jagged-edge boundary on the substrate. A high-precision two-dimensional （2D） mobile stage is used for complementary cyclical scanning, thereby effectively eliminating image stitching errors. The absence of such errors results in a seamless and uniform large-sized grating. Characterized by a simple structure, high energy use, and good stability, this lithography system is highly relevant to the high-speed and cost- effective production of large-sized gratings.     

Simplified mode analysis of guided mode resonance gratings with asymmetric coatings

A simplified modal method to explain the resonance phenomenon in guided mode resonance(GMR) gratings with asymmetric coatings is presented.The resonance observed is due to the interaction of two propagation modes inside the grating.The reflectivity spectra and electric field distributions calculated from the simplified modal method are compared using rigorous coupled-wave analysis(RCWA).The influences of high-order evanescent modes on the resonance peak are analyzed.A matrix Fabry-Perot(FP) resonance condition is developed to evaluate the resonance wavelength.An explanation for the resonance phenomenon observed based on the FP resonance phase condition is also proposed and demonstrated.The simplified method provides clear physical insights into GMR gratings that are useful for the analysis of a variety of other resonance gratings.