Graphene oxide enhanced phase change tolerance of Ge₂Sb₂Se₄Te₁ for all-optical multilevel non-volatile photonics memory

The low optical loss of Ge₂Sb₂Se₄Te₁ (GSST) makes it a potential functional material for all-optical multilevel photonics memory devices that can operate in the optical telecommunication wavelength band. However, the same characteristic also restricted the tolerance of GSST phase change conditions using 1550 nm as an excitation light source. This work reports on the enhancement of GSST phase change condition tolerance using a graphene oxide (GO) intermediate layer on a polymer waveguide platform. The hybrid waveguide exhibits an insertion loss of around 1 dB and a maximum readout contrast of 25% between amorphous and crystalline states, with a step increase in readout contrast of around 5% per step. This work serves as a proof of concept for the implementation of a GSST–GO hybrid structure as an optical functional material in all-optical photonics memory applications.