  The optical memristive switches are electrically activated optical switches
that can memorize the current state. They can be used as optical latching
switches in which the switching state is changed only by applying an electrical
Write/Erase pulse and maintained without external power supply. We demonstrate
an optical memristive switch based on a silicon MMI structure covered with
nanoscale-size Ge2Sb2Te5 (GST) material on top. The phase change of GST is
triggered by resistive heating of the silicon layer beneath GST with an
electrical pulse. Experimental results reveal that the optical transmissivity
can be tuned in a controllable and repeatable manner with the maximum
transmission contrast exceeding 20 dB. Partial crystallization of GST is
obtained by controlling the width and amplitude of the electric pulses.
Crucially, we also demonstrate that both Erase and Write operations, to and
from any intermediate level, are possible with accurate control of the
electrical pulses. Our work marks a significant step forward towards realizing
photonic memristive switches without static power consumption, which are highly
demanded in high-density large-scale integrated photonics.
