Robert Cell-Based Optical Delay Elements for White Cell True-Time Delay Devices

A low-loss and compact optical delay element is devised to be integrated into existing White cell-based true-time delay systems. The delay element is based on a multiple-bounce cell that consists of simple optical components, which was initially described by Claude Robert for spectroscopy. We hereby provide a comprehensive analysis of the Robert cell and propose that it can be modified in a number of ways to produce discrete and variable time delays up to hundreds of ns. The Robert cell show appealing traits compared to traditional optical delay devices because it relies on reflections within a system of mirrors to produce time delays, and this mechanism reduces the physical size and optical losses compared to traditional approaches for long delays. We also illustrate how modified Robert cells can be designed such that they can be compatibly combined with White cell-based true-time delay systems.