Programmable photonic integrated circuits (PICs) are steadily becoming an established technology with a wide range of applications in communications, sensing and analog signal processing. Femtosecond laser written programmable PICs are implemented by means of thermal phase shifters, but until recently only few thermal shifters could be fabricated on the same chip due to their high power dissipation and thermal crosstalk. This limitation can be overcome with the introduction of isolation structures allowing us to fabricate universally programmable PICs with tens of thermal shifters.
