All-optical non-volatile tuning of an AMZI-coupled ring resonator with GST phase-change material

(GST)-integrated ring resonator with the tuning enabled by an all-optical phase change of GST using a sequence of optical pulses. The tuning is non-volatile and repeatable, with no static power consumption due to the "self-holding" feature of the GST phase-change material. The 2 μm long GST can be partially crystallized by controlling the number of pulses, increasing the tuning freedom. The coupling between the ring resonator and the bus waveguide is based on an asymmetric Mach-Zehnder interferometer. The coupling strength is wavelength-dependent, so that an optimal wavelength can be selected for the probe light to get more than 20 dB transmission contrast between the amorphous and crystalline GST states.