Phase change type optical disc

The present invention provides a phase transition optical disk, including a baseplate, a first dielectric layer, a second dielecric layer, a third dielectric layer, a recording layer, a fourth dielectric layer and a reflecting layer, in which the first dielectric layer is formed on the baseplate, and the second dielectric layer is formed on the first dielectric layer, and the refractive index (n2) of second dielectric layer is greater than refractive index (n1) of first dielectric layer, the thrid electric layer is formed on second dielectric layer, the refractive index (n3) of third dielectric layer is less than the refractive index (n2) of second dielectric layer, the recording layer is formed on third dielectric layer, and the fourth dielectric layer is formed on the recording layer, and the reflecting layer is formed on the fourth dielectric layer.