We introduce an approach to enhance the angular tolerance of resonant waveguide gratings by stacking two resonant structures on top of each other. It is shown that reflectivities close to unity can be retrieved over the entire angular spectrum by a double T-shaped grating configuration. Although a combination of silicon as the high-index and diamond as the low-index material is considered, the principles of our new approach can also be used to realize monolithic silicon structures with similar properties. We illustrate that the functionality of the device can be understood by a decomposition into separated elements. Our approach might have compelling applications as new diffractive-reflective optical components with low-coating thermal noise in the field of high-precision metrology.
© 2011 Optical Society of America
Diffraction and Gratings
Original Manuscript: November 2, 2010
Revised Manuscript: December 6, 2010
Manuscript Accepted: December 10, 2010
Published: February 10, 2011
Stefanie Kroker, Frank Brückner, Ernst-Bernhard Kley, and Andreas Tünnermann, "Enhanced angular tolerance of resonant waveguide grating reflectors," Opt. Lett. 36, 537-539 (2011)