Publications Details

High-efficiency diffractive optical elements for spectral beam combining

Kemme, S.A.; Scrymgeour, David S.; Peters, D.W.

We present a broadband, all-dielectric, diffractive optical element (DOE) for spectral beam combining with optimized efficiency. We achieve maximal efficiency and polarization insensitivity for the sum of incident wavelengths by varying grating etch depth and duty cycle of a rectangular profile grating realized with the precision of ebeam mask definition. Design and fabrication considerations that maximize efficiency are quantified, including material options, e-beam defined lithographic parameters such as grating periods and aspect ratios, tailored wavelength dispersion, and polarization independence. These results are compared to published efficiency values of >95% diffraction efficiency for a single polarization and single wavelength and polarization-independent efficiency values of >98% also for a single wavelength. © 2012 Copyright Society of Photo-Optical Instrumentation Engineers (SPIE).