a probe for medical use includes a tip portion having a light energy input region for receiving light energy from a light source and a predetermined light energy output region whereby tissue subtended by the region may be irradiated by the light energy . the tip portion consists essentially of light propagating material having inclusions distributed therein and generally throughout the tip portion between the light energy input region and the light energy output region for interacting with the light energy to produce a predetermined light energy output pattern . the light propagating material is a light propagating inorganic compound .