Spiral delay line
The design proposed above has long delay lines that are hundreds of microns in length. A common practice in Silicon photonics design is to use double spiral shaped waveguides as delay lines.
Although the EBeam SDK has a K-layout plugin to "resize" the waveguide to a specific total length, it is still a challenging task to draw and control the length of spirals. A MATLAB script is written to generate parametric spirals, the coordinates of the spiral path are used in K-layout to define spirals.