Miniature FT-MIR using a MEMS interferometer with a metasurface emitter and detector

1. A miniature Fourier transform mid-infrared (FT-MIR) spectrometer, comprising:

a metasurface IR source to emit radiation when heated;

a microelectromechanical (MEMS) interferometer; and

a metasurface microbolometer to measure an interferogram from the MEMS interferometer, wherein the miniature FT-MIR spectrometer is less than about 20 mm in outer diameter.

2. The miniature FT-MIR spectrometer of claim 1 , comprising an attenuated total reflectance prism.

3. The miniature FT-MIR spectrometer of claim 1 , wherein the metasurface IR source comprises an electrically conductive geometric pattern based on a geometric inversion of the Rhodonea conformal mapping contours.

4. The miniature FT-MIR spectrometer of claim 1 , wherein the metasurface IR source comprises an electrically conductive geometric pattern based on a geometric inversion of the Tangent Circles conformal mapping contours.

5. The miniature FT-MIR spectrometer of claim 1 , wherein the metasurface IR source is tuned to emit radiation from about 500 wavenumbers (cm −1 ) to about 2000 cm −1 .

6. The miniature FT-MIR spectrometer of claim 1 , wherein the metasurface IR source comprises a heating filament to heat the metasurface IR source to about 900 K.

7. The miniature FT-MIR spectrometer of claim 1 , wherein the MEMS interferometer, comprises:

a pair of movable mirrors that are positioned along perpendicular axes, wherein each of the pair of movable mirrors is coupled to a mechanism comprising:

an electrostatic actuator driving a displacement amplification mechanism; and

the displacement amplification mechanism driving each of the pair of the movable mirrors; and

a beam splitter positioned at an intersection of the perpendicular axes extending through each movable mirror and the beam splitter; and

the metasurface microbolometer placed in line with the beam splitter to measure an intensity of a recombined beam from the pair of movable mirrors.

8. The miniature FT-MIR spectrometer of claim 7 , wherein the MEMS interferometer comprises a single chip.

9. The miniature FT-MIR spectrometer of claim 8 , wherein the single chip is about 9.2 mm×9.2 mm.

10. The miniature FT-MIR spectrometer of claim 7 , wherein the electrostatic actuator comprises:

a central actuator attached to a movable comb, wherein the movable comb comprise grounded tines;

a positive comb comprising positive tines, wherein the positive tines are interspersed with the grounded tines on a first side of the movable comb;

a negative comb comprising negative tines, wherein the negative tines are interspersed with the grounded tines on a second side of the movable comb;

a sway stabilizer attached to the central actuator at one end; and

a coupling from the central actuator to the displacement amplification mechanism at an opposite end from the sway stabilizer.

11. The miniature FT-MIR spectrometer of claim 7 , wherein the displacement amplification mechanism comprises:

a symmetric fulcrum coupled to a central actuator of the electrostatic actuator; and

three serpentine release flexures, wherein the serpentine release flexures allow moment release on the fulcrum to amplify the displacement from the central actuator to increase a motion of the movable mirror.

12. The miniature FT-MIR spectrometer of claim 11 , wherein the displacement amplification mechanism increases the motion of the movable mirror by a factor of nine over the motion of the central actuator.

13. The miniature FT-MIR spectrometer of claim 1 , wherein the metasurface microbolometer comprises:

a metasurface tuned to adsorb radiation in a range of frequencies in the mid infrared;

a thermometric layer in contact with the metasurface, wherein the thermometric layer changes in resistivity with temperature changes;

a dielectric substrate supporting the thermometric layer and the metasurface; and

a readout integrated circuit to measure a response from the thermometric layer comprising a voltage drop across the contacts of the bridge with a constant bias current.

14. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface is tuned to adsorb radiation from about 500 wavenumbers (cm −1 ) to about 2000 cm −1 .

15. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface comprises gold.

16. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface absorbs light through surface plasmon resonances.

17. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface is about 120 nm in thickness.

18. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface is less than 30 nm in thickness.

19. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface has a diameter of about 150 μm.

20. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface has a 35% fill factor.

21. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface has a detectivity (D*) of about 1×10 10 cm*sqrt (Hz)/W at 333 K at a bias current of 75 μA.

22. The miniature FT-MIR spectrometer claim 13 , wherein the metasurface has a noise equivalent difference temperature (NEDT) of about 1 mK at a bias current of 75 μA.

23. The miniature FT-MIR spectrometer of claim 13 , wherein the thermometric layer comprises undoped vanadium oxide (VO 2 ).

24. The miniature FT-MIR spectrometer of claim 13 , wherein the thermometric layer is about 500 nm in thickness.

25. The miniature FT-MIR spectrometer of claim 13 , wherein the dielectric substrate comprises silicon nitride (Si 3 N 4 ).

26. The miniature FT-MIR spectrometer of claim 13 , wherein the dielectric substrate is about 200 nm in thickness.

27. The miniature FT-MIR spectrometer of claim 13 , wherein the dielectric substrate is about 100 nm in thickness.

28. The miniature FT-MIR spectrometer of claim 13 , wherein the dielectric substrate is separated from the readout integrated circuit by an airgap.

29. The miniature FT-MIR spectrometer of claim 13 , wherein the metasurface microbolometer has a broadband absorption of more than 90% in a wavenumber range of about 1500 to about 600 cm −1 .

30. The miniature FT-MIR spectrometer of claim 1 , wherein the metasurface microbolometer has an absorption bandwidth of 156% of full width half maximum (FWHM) centered on a wavenumber of 1070 cm −1 .