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 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 comprising a plurality of reflection structures that are periodically arranged,
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 of 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, the duty cycle of the plurality of reflection structures being a ratio between a width of each of the plurality of reflection structures and the pitch of each of the plurality of reflection structures.
4. The light filter of claim 1 , wherein the plurality of reflection structures are arranged one-dimensionally.
5. The light filter of claim 4 , wherein the plurality of reflection structures are arranged in parallel lines.
6. The light filter of claim 1 , wherein the plurality of reflection structures are arranged two-dimensionally.
7. The light filter of claim 6 , wherein the plurality of reflection structures are repeatedly arranged in a polygonal pattern.
8. The light filter of claim 1 , wherein the Bragg reflection layer comprises a plurality of material layers respectively having different refractive indexes that are alternately stacked.
9. The light filter of claim 1 , wherein the pattern reflection layer further comprises a plurality of connection layers configured to connect adjacent reflection structures, and
wherein a thickness of each of the plurality of connection layers is less than a thickness of the plurality of reflection structures.
10. A spectrometer comprising:
a light filter comprising a plurality of filter units, the plurality of filter units having different resonance wavelengths; and
a sensor configured to receive light that has passed through the light filter,
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; and
a pattern reflection layer comprising a plurality of reflection structures that are provided on a second surface of the cavity layer opposite to the first surface or included in the cavity layer, the pattern reflection layer being configured to cause guided mode resonance of light incident on the pattern reflection layer,
wherein the plurality of reflection structures are provided on the second surface of the cavity layer,
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.
11. The spectrometer of claim 10 , 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.
12. The spectrometer of claim 10 , wherein a resonance wavelength of each of 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, the duty cycle of the plurality of reflection structures being a ratio between a width of each of the plurality of reflection structures and the pitch of each of the plurality of reflection structures.
13. The spectrometer of claim 10 , wherein the plurality of reflection structures are arranged one-dimensionally or two-dimensionally.
14. The spectrometer of claim 10 , wherein the plurality of reflection structures are provided in the cavity layer, and
wherein each of the plurality of filter units further comprises a second Bragg reflection layer provided on the second surface of the cavity layer.
15. The spectrometer of claim 14 , wherein the plurality of reflection structures are in contact with the first Bragg reflection layer and the second Bragg reflection layer.
16. The spectrometer of claim 10 , wherein the sensor comprises an image sensor or a photodiode.