Impact of Process Variations on the Performance of Wavelength-Dependent Devices

Abstract

One of the main factors for the rapid growth and industrialization of the integrated photonics field was the previous development by the microelectronics sector of lithography tools and processes for complementary metal oxide semiconductor fabrication, now also employed in the fabrication of photonic integrated circuits. However, the scarce range of methods to fine-tune photonic devices during the lithographic process results in a disparity between designed and manufactured devices. For the current state of lithographic resolution, when considering wavelength-dependent devices, such as Bragg gratings, this disparity can significantly alter the design of the component and impact its performance, as the response strongly depends on its geometry. Thus, understanding the impact of lithography in a photonic component is extremely important to minimize these variations and optimize the design process. This chapter explores the impact of manufacturing process variations, studying their effect on device geometry through a case study on contra-directional couplers, toward ultimately reducing the existing gap between designers and foundries.