Light capturing sheet and light capturing rod, and light receiving device, light emitting device and optical fiber amplifier using the same

摘要

The light capturing sheet includes a translucent sheet and a plurality of light coupling structures disposed therein. The optical coupling structure includes a first light-transmitting layer, a second light-transmitting layer, a third light-transmitting layer sandwiched therebetween, and a diffraction grating. The refractive index of the first and second light transmissive layers is smaller than the refractive index of the light transmissive sheet, and the refractive index of the third light transmissive layer is larger than the refractive indexes of the first and second light transmissive layers. The light coupling structure is arranged in first and second directions on a plane parallel to the main surface of the translucent sheet, and a third direction non-parallel thereto. An optical coupling structure that constitutes a group of optical coupling structures arranged on one plane and an optical coupling structure that is arranged on another plane and is adjacent to the group of optical coupling structures in the third direction The optical coupling structure that does not overlap in the third direction. The third light-transmitting layer in the first optical coupling structure in the group of optical coupling structures and the third optical coupling structure in the second optical coupling structure adjacent to the first optical coupling structure in the other group of optical coupling structures. The light transmissive layer is connected to the third light transmissive layer through a connection portion made of the same material.