Light receiving module and light receiving method with reduced polarization dependence

摘要

The light receiving module has an optical mechanism 18 including a first light transmission plate 14a and a second light transmission plate 15a between a first lens 12 and a second lens 16, and a light receiving element 13 of the outside of the optical mechanism 18. The light receiving element 13 is placed adjacent to the first light transmission plate 14a with the second lens 12 sandwiched, and the light receiving element 13 is placed with a light receiving surface 13b inclined with respect to an optical axis of incident light 11a. In the optical mechanism 18, the first light transmission plate 14a is inclined at such an angle as to have the same value as polarization dependence due to the inclination of the light receiving surface 13b of the light receiving element 13, and subsequently the first light transmission plate 14a is rotated by 90° in relation to the optical axis 11a. The second light transmission plate 15a is inclined at such an angle that the sum of the polarization dependence of the first transmission plate 14a and a polarization dependence of the second transmission plate 15a is equal to the polarization dependence due to the inclination of the light receiving surface 13b of the light receiving element 13 to cancel out the remaining polarization dependence, and subsequently the second light transmission plate 15a is rotated by 90° in relation to the optical axis 11a.