| CPC H10F 77/413 (2025.01) [H04N 25/62 (2023.01); H10F 39/12 (2025.01); H10F 55/25 (2025.01); H10F 77/50 (2025.01); H10F 77/707 (2025.01)] | 13 Claims |
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1. An optical detection device comprising:
an optical semiconductor element having a plurality of light receiving portions; and
a light transmitting substrate composed of a single member bonded to the optical semiconductor element directly or via only a light transmitting adhesive layer,
wherein a surface of the light transmitting substrate on a side opposite to the optical semiconductor element is provided with a first refractive index changing layer having a projecting and recessed structure in which a refractive index continuously changes from a refractive index of air to a refractive index of the light transmitting substrate toward the light transmitting substrate,
wherein in the projecting and recessed structure, a plurality of projections or a plurality of recesses are arranged at a distance between centers of 100 nm to 200 nm, and a height of each of the plurality of projections or a depth of each of the plurality of recesses is 50 nm to 400 nm,
wherein, a distance between the optical semiconductor element and the first refractive index changing layer is A (A>50 μm), a distance between adjacent light receiving portions of the plurality of light receiving portions is B, a refractive index of the light transmitting substrate to a refractive index of the air is n, and A>B/[2tan{sin−1(sin1°/n)}] is established, and
wherein each of the plurality of light receiving portions includes a configuration of an avalanche photodiode such that self-light-emission can occur due to recoupling of electric charges.
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