Optical Directivity Design Using Through-hole Array Silicon Chip

In this letter, we report a method of designing the optical sensor directivity without using an optical lens. The directivity is realized by attaching the designed through-hole array chip on an optical sensor surface. The through-hole array chip can be formed by a conventional semiconductor manufacturing technique. The directivity can be designed by adjusting the through-hole size and the chip thickness. Its performance is evaluated using the manufactured test chip. For visible light, when the through hole width is 25 μm and the partition wall thickness between them is 10 μm, the directivity is about 4° and the light transmittance is about 31%. Although directivity is slightly broad for near-infrared light, it can be designed utilizing the trade-off between directivity and transmittance. The proposed method enables us to reduce the sensor size to one-tenth or less of that using optical lenses.