Polarization state generation with a metasurface
The present disclosure provides an optical component, which may be a metasurface grating, including (a) a substrate; and (b) an array of subwavelength-spaced phase-shifting elements, which are tessellated on the substrate to produce, when illuminated with a polarized incident light, a diffracted light beam with a distinct polarization state for each of a finite number of diffraction orders, wherein the finite number is 2 or more.
1. A detector comprising:
a substrate;
an array of subwavelength-spaced phase-shifting elements disposed on the substrate and configured to produce, when illuminated with a polarized incident light, a diffracted light beam with a distinct polarization state for each of a finite number of diffraction orders, wherein the finite number is 2 or more; and
one or more detecting elements, each configured to detect the diffracted light beam for one of the diffraction orders.
2. The detector of claim 1 , wherein the array is a one-dimensional array.
3. The detector of claim 1 , wherein the phase-shifting elements comprise pillars.
4. The detector of claim 3 , wherein the pillars have a rectangular cross-section.
5. The detector of claim 1 , wherein the phase-shifting elements comprise titanium dioxide, silicon nitride, an oxide, a nitride, a sulfide, or a pure element.
6. The detector of claim 1 , wherein the subwavelength-spaced phase-shifting elements are tessellated on the substrate and are configured to produce, when illuminated with the polarized incident light, four distinct polarization states.
7. The detector of claim 6 , wherein the subwavelength-spaced phase-shifting elements are further configured to produce a +45° linear polarization state, a right circular polarization state, a left circular polarization state and a −45° linear polarization state at −2, −1, +1 and +2 diffraction orders, respectively, when illuminated with the polarized incident light which is +45° linear polarized relative to a surface of the substrate.
8. The detector of claim 6 , wherein the subwavelength-spaced phase-shifting elements are further configured to produce at −2, −1, +1 and +2 diffraction orders four polarization states corresponding to vertices of a tetrahedron inscribed in a Poincaré sphere when illuminated with the polarized incident light which is +45° linear polarized relative to a surface of the substrate.
9. The detector of claim 1 , wherein each dimension of the substrate parallel to a surface of the substrate is no more than 2 millimeters.
10. The detector of claim 1 , wherein a number of the subwavelength-spaced phase-shifting elements is in a range from 10 to 40.
11. The detector of claim 1 , wherein polarization states for each of the diffraction orders are linearly independent.
12. The detector of claim 1 , wherein the one or more detecting elements comprise one or more single-wavelength detecting elements, one or more multi-wavelength detecting elements, or one or more imaging sensors.
13. The detector of claim 12 , wherein the single-wavelength detecting elements are linear in intensity at a wavelength of the polarized incident light.
14. The detector of claim 1 , further comprising a first linear polarizer positioned on an optical path of an incident light towards the array of subwavelength-spaced phase-shifting elements.
15. The detector of claim 14 , further comprising a second linear polarizer on an optical path of the diffracted light beam towards the one or more detecting elements.
16. The detector of claim 15 , wherein an extinction ratio of the second linear polarizer is in a range from 500 to 200000.
17. The detector of claim 1 , further comprising a lens positioned on an optical path of the diffracted light beam towards the one or more detecting elements.
18. The detector of claim 1 , wherein the one or more detecting elements comprises one or more imaging sensor elements.
19. A polarization test method comprising:
providing a detector comprising:
a substrate;
an array of subwavelength-spaced phase-shifting elements disposed on the substrate and configured to produce, when illuminated with a polarized incident light, a diffracted light beam with a distinct polarization state for each of a finite number of diffraction orders, wherein the finite number is 2 or more; and
one or more detecting elements, each configured to detect the diffracted light beam for one of the diffraction orders;
illuminating the array of subwavelength-spaced phase-shifting elements with a test light; and
measuring a light intensity of a beam diffracted from the array of subwavelength-spaced phase-shifting elements for each of the finite number of the diffraction orders using the one or more detecting elements.
20. The method of claim 19 , wherein the test light is a partially polarized or an unpolarized light.
21. The method of claim 19 , wherein an incident angle of the test light differs from a calibration incident angle of the optical component by ±5°.