Efficient ultrathin all-dielectric nonlinear optical device
An apparatus and method are provided for generating harmonic light from a pump beam that is impinged on a metasurface comprising a plurality of all-dielectric resonator bodies. A multiple quantum well structure formed in each resonator body includes asymmetric coupled quantum wells having intersubband transition frequencies that couple to Mie resonances of the resonator bodies.
1. Apparatus comprising a metasurface in which a plurality of elements is disposed on a substrate surface, wherein:
each of the elements is an all-dielectric resonator body conformed to resonate at a first resonant frequency;
each of the elements has at least some resonant response at a second resonant frequency that is a multiple of the first resonant frequency;
each of the elements includes at least one multiple quantum well (MQW) structure constituted by a sequence of layers that defines multiple quantum wells;
each MQW structure comprises at least one coupled quantum well (coupled QW) in which two or more dissimilar quantum wells are disposed sequentially;
each of the coupled QWs is dimensioned to have at least a first, a second, and a third electronic eigenstate having respective energy levels;
the eigenstate energy levels are separated from each other by transition energies, each corresponding to a respective optical transition frequency;
the first resonant frequency is substantially equal to one of the optical transition frequencies; and
the second resonant frequency is substantially equal to another of the optical transition frequencies.
2. The apparatus of claim 1 , wherein the transition energies are energies of intersubband transitions of the MQW structures.
3. The apparatus of claim 1 , wherein the elements are disposed in a periodic pattern on the substrate surface.
4. The apparatus of claim 1 , wherein each of the resonator bodies is conformed to resonate at both the first and second resonant frequencies.
5. The apparatus of claim 1 , wherein the first, second, and third electronic eigenstates have respective energy levels separated from each other by substantially equal separations in energy.
6. The apparatus of claim 1 , wherein each of the resonator bodies comprises III-V semiconductor material.
7. The apparatus of claim 1 , wherein each of the MQW structures is an InGaAs/AlInAs heterostructure.
8. The apparatus of claim 1 , wherein the first resonant frequency belongs to a fundamental Mie resonance of the all-dielectric resonator bodies.
9. The apparatus of claim 1 , wherein the first resonant frequency is a frequency of a magnetic dipole resonance of the all-dielectric resonator bodies.
10. The apparatus of claim 1 , wherein the second resonant frequency lies within a portion of the electromagnetic spectrum extending from a vacuum wavelength of 1.5 μm to a vacuum wavelength of 4 μm.
11. The apparatus of claim 1 , wherein each of the all-dielectric resonator bodies comprises Group-III antimonide material.
12. The apparatus of claim 1 , wherein each of the MQW structures is an AlSb/InAs/AlSb heterostructure.
13. The apparatus of claim 1 , wherein each of the coupled QWs has exactly two dissimilar quantum wells.
14. The apparatus of claim 1 , wherein each of the coupled QWs has exactly three dissimilar quantum wells.
15. A method for generating harmonic light from a pump beam of light having a pump frequency, comprising:
impinging the pump beam on a metasurface comprising a plurality of all-dielectric resonator bodies, such that a Mie resonance is excited in each of the said bodies; and
collecting harmonic light from the metasurface, the harmonic light having a frequency that is a multiple of the pump frequency, wherein:
the impinging of the pump beam excites a fundamental intersubband transition (IST) of MQW heterostructures contained within the said bodies, wherein the fundamental IST is coupled to a Mie resonance supported by the said bodies; and
the impinging of the pump beam further excites at least one higher-order IST of the said MQW heterostructures, wherein the higher-order IST has a transition frequency that overlaps at least one Mie-resonant response of the said bodies having a frequency that is a harmonic of the pump frequency.
16. The method of claim 15 , wherein the harmonic of the pump frequency is the second harmonic.
17. The method of claim 15 , wherein the harmonic of the pump frequency is the third harmonic.
18. The method of claim 15 , wherein the Mie resonance excited by impinging the pump beam is a fundamental Mie resonance of the all-dielectric resonator bodies.
19. The method of claim 15 , wherein the Mie resonance excited by impinging the pump beam is a magnetic dipole resonance of the all-dielectric resonator bodies.
20. The method of claim 15 , wherein the harmonic light lies within a portion of the electromagnetic spectrum extending from a vacuum wavelength of 1.5 μm to a vacuum wavelength of 4 μm.