Silicon nanomembrane based photonic crystal waveguide true-time-delay lines on a glass substrate

We demonstrate photonic crystal waveguide true-time-delay lines fabricated on a large area (>2cm × 2cm) silicon nanomembrane transferred onto a glass substrate. The photonic crystal waveguides are designed to provide large time delay values within a short length. 17.1 μm × 10 μm subwavelength grating (SWG) couplers are employed in order to enable efficient light coupling from and to a fiber. Photonic crystal tapers are implemented at the stripphotonic crystal waveguide interfaces to minimize loss and provide larger time delay values. A large group index of ~28.5 is calculated from the measurement data, thus indicating achievability of time delay larger than 58ps per millimeter length of the delay line within a tuning range of 20nm.

https://doi.org/10.1117/12.2004731