The dramatic optical property change of optical phase change materials (O-PCMs) allows the realization of tunable optical and photonic devices with enhanced optical functionalities, such as reconfigurable optics, optical switches and routers, and photonic memories. Recently we developed a new class of non-volatile O-PCM, Ge-Sb-Se-Te (GSST), which features unprecedented broadband optical transparency (1-18.5 micron), large optical contrast (dn = 2) and significantly improved glass forming ability. Leveraging the remarkable material property and advanced design methods, we develop a suite of reconfigurable, all-dielectric metasurface optics with unprecedented performance. In one example, a focal length tunable transmissive metalens is demonstrated showing diffraction-limited imaging performance and complete optical function switching during the phase transition, which sets the foundation for ultra-compact, solid-state, tunable meta-optical systems.