We present here, our most recent results from theoretical and experimental investigations of optical properties of coupled microresonators. While fused silica spherical microresonators with Q-factors of about 107 to 108 can be quite easily fabricated, the production of a number of equally sized spheres, which appears to be a necessary condition for effective light coupling, has proved challenging. In order to bypass this problem we focus our attention on the investigation of coupled disk microresonators made of fused silica. These may be fabricated in almost arbitrary two-dimensional configuration with nanometer precision. A Q-factor of 105 can be routinely achieved, which relaxes the requirements on uniformity of the microdisks to within the range of fabrication accuracy. The achieved Q-factors are high enough to observe thermal nonlinear effects in the fabricated coupled disks. A detailed experimental analysis of the thermal nonlinear resonance behavior in a system of two coupled microdisks now follows. The results were found to be in good agreement with the respective calculations based on coupled mode theory including temperature induced nonlinear response.