We demonstrate externally photo-induced partially-reversible tuning of the resonance of a microdisk made of AMTIR-1 (Ge33As12e55). We have achieved for the first time, to the best of our knowledge, both positive and negative shift in a microresonator with external tuning. A positive resonance shift of 1 nm and a negative resonance shift of 0.5 nm on a single microdisk has been measured. We have found that this phenomenon is due to initial photo-expansion of the microdisk followed by the photo-bleaching of the AMTIR-1. The observed shifts and the underlying phenomenon is controllable by varying the illumination power (i.e. the low power illumination suppresses the photobleaching process). We measure a loaded quality factor of 1.2×105 at 1550nm (limited by the measuring instrument). This holds promise for non-contact low power reversible-tunning of photonic circuit elements.