Phase shifters are devices that offer the possibility to dynamically reconfigure the properties of photonic integrated circuits (PICs), thus greatly extending their quality and applicability. In this paper, we provide a thorough discussion of the main problems that one can encounter when using thermal phase shifters. We show how all these issues can be solved and the performance improved by manufacturing optimized thermal shifters in femtosecond-laser-written PICs (FLW-PICs). The unprecedented results in terms of power dissipation, miniaturization and stability enable the scalable implementation of reconfigurable FLW-PICs for exploitation in many applications.
With this work, we report on the quantum storage of a heralded frequency-multiplexed single photon in an integrated laser-written rare-earth doped waveguide. In particular, a frequency-multimode photon is stored in a praseodymium-doped waveguide using the atomic frequency comb (AFC) scheme and we demonstrate that the storage preserves the nonclassical properties of the single photon.