Practical Implementation of Broadband Diffractive Optical Elements

Diffractive optical elements (DOEs), with their thin profile and unique dispersion properties, have been studied and utilized in a number of optical systems, often yielding smaller and lighter systems. Despite the interest in and study of DOEs, the application of DOEs has been limited to narrow spectral bands. This is due to DOEs depths, which are optimized for optical path differences of only a single wavelength, consequently leading to rapid decline in efficiency as the working wavelength shifts away from the design wavelength. Various broadband DOE design methodologies have recently been developed that improve spectral diffraction efficiency and expand the working bandwidth of diffractive elements. Two such extended bandwidth diffractive designs have been modeled and fabricated. The diffraction efficiency test result for one broadband DOE design is presented.