Light filter and spectrometer including the same
A light filter and a spectrometer including the light filter are disclosed. The light filter includes a plurality of filter units having different resonance wavelengths, wherein each of the plurality of filter units includes a cavity layer configured to output light of constructive interference, a Bragg reflection layer provided on a first surface of the cavity layer, and a pattern reflection layer provided on a second surface of the cavity layer opposite to the first surface and configured to cause guided mode resonance of light incident on the pattern reflection layer, the pattern reflection layer including a plurality of reflection structures that are periodically arranged.
1. A light filter comprising:
a plurality of filter units having different resonance wavelengths,
wherein each of the plurality of filter units comprises:
a cavity layer configured to output light of constructive interference;
a first Bragg reflection layer provided on a first surface of the cavity layer;
a second Bragg reflection layer provided on a second surface of the cavity layer opposite to the first surface; and
a pattern reflection layer provided in the cavity layer and configured to cause guided mode resonance of light incident on the pattern reflection layer, the pattern reflection layer comprising a plurality of reflection structures that are two-dimensionally arranged in a hexagonal pattern, wherein the plurality of reflection structures do not include a reflection structure provided at a center of the hexagonal pattern,
wherein the pattern reflection layer further comprises a filling layer filled in gaps between the plurality of reflection structures, the filling layer being in contact with side surfaces of each of the plurality of reflection structures, and
wherein a refractive index of the filling layer is different from a refractive index of the plurality of reflection structures.
2. The light filter of claim 1 , wherein the plurality of reflection structures are periodically arranged with a pitch less than a resonance wavelength of each of the plurality of filter units.
3. The light filter of claim 1 , wherein a resonance wavelength of each the plurality of filter units is determined by at least one of a pitch, a thickness, and a duty cycle of the plurality of reflection structures.
4. The light filter of claim 1 , wherein each of the first Bragg reflection layer and the second Bragg reflection layer respectively comprises a plurality of material layers having different refractive indexes that are alternately stacked.
5. The light filter of claim 1 , wherein the plurality of reflection structures are provided on a surface of the first Bragg reflection layer adjacent to the first surface of the cavity layer or a surface of the second Bragg reflection layer adjacent to the second surface of the cavity layer.
6. The light filter of claim 1 , wherein the plurality of reflection structures are in contact with the first Bragg reflection layer and the second Bragg reflection layer.
7. A light filter comprising:
a plurality of filter units having different resonance wavelengths,
wherein each of the plurality of filter units comprises:
a cavity layer configured to output light of constructive interference;
a first Bragg reflection layer provided on a first surface of the cavity layer;
a second Bragg reflection layer provided on a second surface of the cavity layer opposite to the first surface; and
a pattern reflection layer provided in the cavity layer and configured to cause guided mode resonance of light incident on the pattern reflection layer, the pattern reflection layer comprising a plurality of reflection structures that are two-dimensionally arranged in a pattern, wherein intervals between two adjacent reflection structures of the plurality of reflection structures in a cross-section of a filter unit in a predetermined direction are irregular,
wherein the pattern reflection layer further comprises a filling layer filled in gaps between the plurality of reflection structures, the filling layer being in contact with side surfaces of each of the plurality of reflection structures, and
wherein a refractive index of the filling layer is different from a refractive index of the plurality of reflection structures.
8. The light filter of claim 7 , wherein the plurality of reflection structures are periodically arranged with a pitch less than a resonance wavelength of each of the plurality of filter units.
9. The light filter of claim 7 , wherein a resonance wavelength of each the plurality of filter units is determined by at least one of a pitch, a thickness, and a duty cycle of the plurality of reflection structures.
10. The light filter of claim 7 , wherein each of the first Bragg reflection layer and the second Bragg reflection layer respectively comprises a plurality of material layers having different refractive indexes that are alternately stacked.
11. The light filter of claim 7 , wherein the plurality of reflection structures are provided on a surface of the first Bragg reflection layer adjacent to the first surface of the cavity layer or a surface of the second Bragg reflection layer adjacent to the second surface of the cavity layer.
12. The light filter of claim 7 , wherein the plurality of reflection structures are in contact with the first Bragg reflection layer and the second Bragg reflection layer.