| 摘要 |
A photodetector which comprises a photodiode comprising a substrate, a light absorbing region and electrodes to the substrate and the light absorbing region, the photodiode having a light-collecting surface. A Fabry-Perot cavity is formed upon the light-collecting surface. The Fabry-Perot cavity includes, in an ascending order from the light collecting surface, a distributed Bragg reflector (DBR) bottom mirror, an active region and a DBR top mirror. Each of the top and bottom mirrors comprises periods, each period comprising a layer of a material with higher refractive index than the other layer in the period, a layer with higher refractive index in one period being adjacent to a layer with a lower refractive index in another period of the mirror, each of the layers in the DBR mirrors being lambda/4 thick. The active region having a refractive index which is different from a refractive index of each adjacent layer in the periods adjoining the light absorbing region, the active region being lambda/2 thick. The material with high refractive index is selected from Si, ZnS, TiO2, GaP, cubic zirconia and SiNx; the material with low refractive index is selected from TiO2, SiNx, cubic glass, borosilicate glass, SiO2, MgF2 and CaF2; the photodiode comprises an InGaAs light absorbing region grown on an InP substrate, and the active region comprises SiO2. |
