| 摘要 |
PROBLEM TO BE SOLVED: To solve the problems that the conventional photodetector cannot correspond to a slim size because of a configuration having a resin package and wire bonding to increase the size of the photodetector, that an S/N of a reproduction signal is bad because a luminous flux of 405 nm cannot secure transmittance corresponding to a multilayer optical disk of low reflectivity due to four layers of a multilayer antireflection layer on a light reception part, and further that specifications of a light reception part of a BD and a multilayer antireflection layer on a light reception part of a DVD and a CD have to be changed to correspond to a three-wavelength light source.SOLUTION: A photodetector 120 which can eliminate reflection loss and obtain a reproduction signal excellent in an S/N is achieved by adjusting a refraction index of a glass package 125 of the photodetector 120 to a reflection index of an adhesion layer 124 (silicone resin) to make a multilayer antireflection layer 128 three layers, reducing the number of layers of the multilayer antireflection layer 128. |
