Continuous Broadband MWP True-Time Delay With PbS-PMMA and PbS-SU8 Waveguides

A new microwave true-time delay (TTD) photonic unit based on the dispersion of PbS colloidal quantum dots (QDs) in a polymethyl methacrylate (PMMA) and the SU8 photoresist is presented. With this aim, the PbS-PMMA and PbS-SU8 nanocomposites are integrated on a silicon platform in the form of the planar and ridge waveguides, respectively. When the PbS QDs on those structures are pumped below their bandgap, a phase shift and a temporal delay in an optically conveyed (at 1550 nm) microwave signal is performed. The results of these devices show potential benefits over current TTD technologies, since the proposed photonic waveguide structures allow real-time adjustment of the temporal delay by tuning the power of the pumping signal, more than 3.5 ps over 25 GHz, and a high level of integration due to the novel proposed photonic waveguide structures and the materials used.