Photodetection device, photodetection system, and filter array

A filter array comprising:

• a plurality of filters arranged in a two-dimensional array, wherein:
• the plurality of filters includes a first filter and a second filter,
• the first filter and the second filter each include a first reflective layer, a second reflective layer, and an intermediate layer between the first reflective layer and the second reflective layer and having a resonant structure,
• a transmission spectrum of each of the first filter and the second filter being different from each other and having local maximum values of transmittance, and
• the first reflective layer includes:
• a plurality of first dielectric layers each having a first refractive index, and
• a plurality of second dielectric layers each having a second refractive index that is higher than the first refractive index,
• the plurality of first dielectric layers and the plurality of second dielectric layers are alternately disposed in the first reflective layer,
• at least two of the plurality of first dielectric layers have thicknesses differing from each other,
• at least two of the plurality of second dielectric layers have thicknesses differing from each other,
• the second reflective layer includes:
• a plurality of third dielectric layers each having a third refractive index, and
• a plurality of fourth dielectric layers each having a fourth refractive index that is higher than the third refractive index,
• the plurality of third dielectric layers and the plurality of fourth dielectric layers are alternately disposed in the second reflective layer,
• at least two of the plurality of third dielectric layers have thicknesses differing from each other,
• at least two of the plurality of fourth dielectric layers have thicknesses differing from each other,
• one end layer of the second reflective layer is in direct contact with the intermediate layer and another end layer of the second reflective layer is in direct contact with a substrate,
• in at least a part of the first reflective layer, a thickness of each of the plurality of first dielectric layers and a thickness of each of the plurality of second dielectric layers gradually decrease along a first direction away from the intermediate layer, and
• in an entirety of the second reflective layer, a thickness of each of the plurality of third dielectric layers and a thickness of each of the plurality of fourth dielectric layers gradually decrease along the first direction.

A photodetection device comprising:

• a filter array including a plurality of filters arranged in a two-dimensional array, the plurality of filters including a first filter and a second filter, the first filter and the second filter each including a first reflective layer, a second reflective layer, and an intermediate layer between the first reflective layer and the second reflective layer and having a resonant structure, a transmission spectrum of each of the first filter and the second filter being different from each other and has local maximum values of transmittance;
• and
• an image sensor disposed at a position where the image sensor receives light having passed through the filter array, wherein:
• the first reflective layer includes:
• a plurality of first dielectric layers each having a first refractive index, and
• a plurality of second dielectric layers each having a second refractive index that is higher than the first refractive index,
• the plurality of first dielectric layers and the plurality of second dielectric layers are alternately disposed in the first reflective layer,
• at least two of the plurality of first dielectric layers have thicknesses differing from each other,
• at least two of the plurality of second dielectric layers have thicknesses differing from each other,
• the second reflective layer includes:
• a plurality of third dielectric layers each having a third refractive index, and
• a plurality of fourth dielectric layers each having a fourth refractive index that is higher than the third refractive index,
• the plurality of third dielectric layers and the plurality of fourth dielectric layers are alternately disposed in the second reflective layer,
• at least two of the plurality of third dielectric layers have thicknesses differing from each other,
• at least two of the plurality of fourth dielectric layers have thicknesses differing from each other,
• one end layer of the second reflective layer is in direct contact with the intermediate layer and another end layer of the second reflective layer is in direct contact with a substrate,
• in at least a part of the first reflective layer, a thickness of each of the plurality of first dielectric layers and a thickness of each of the plurality of second dielectric layers gradually increase along a first direction away from the intermediate layer, and
• in an entirety of the second reflective layer, a thickness of each of the plurality of third dielectric layers and a thickness of each of the plurality of fourth dielectric layers gradually increase along the first direction.