  Efficient heat management and control in optical devices, facilitated by
advanced thermo-optic materials, is critical for many applications such as
photovoltaics, thermal emitters, mode-locked lasers, and optical switches.
Here, we investigate the thermo-optic properties of 2D graphene oxide (GO)
films by precisely integrating them onto microring resonators (MRRs) with
control over the film thicknesses and lengths. We characterize the refractive
index, extinction coefficient, thermo-optic coefficient, and thermal
conductivity of for the GO films with different layer numbers and degrees of
reduction, including reversible reduction and enhanced optical bistability
induced by photo-thermal effects. Experimental results show that the
thermo-optic properties of 2D GO films vary widely with the degree of
reduction, with significant polarization anisotropy, enabling efficient
polarization sensitive devices. The versatile thermo-optic response of 2D GO
substantially expands the scope of functionalities and devices that can be
engineered, making it promising for a diverse range of thermo-optic
applications.
