Abstract

Recently, there has been considerable research activity on WDM devices,^1-3 in which curved gratings were utilized as the wavelength-selective elements. The Rowland circle grating, which was designed to minimize the diffraction aberrations (up to the second order), is the most commonly used curved grating structure.⁵ The diffracted optical image from a curved grating exhibits both aberration and diffraction effects. To achieve the best optical image (spot size and shape), and the lowest cross talk (between two adjacent output waveguide channels), an optimal grating size should be used for a given device structure. In this paper, we present a detailed analysis of the design issues related to the curved grating and its corresponding waveguides. The performance of the Rowland circle gratings was studied by evaluating the point spread function (PSF) of the gratings.⁴

© 1994 Optical Society of America