1. Fabry Perot cavity based microspectrometer Aamer Mahmood Donald P. Butler Ph.D. Department of Electrical Engineering University of Texas at Arlington, TX 76019 Sponsored by the National Science Foundation

2. Electromagnetic interference Electromagnetic energy from different sources will interfere when sharing the same space

3. Electromagnetic interference Interference depends on the phase of each component Constructive interference

4. A Fabry Perot cavity creates multiple sources with different phase from a single source Incident radiation Transmitted radiation Reflecting surface

5. Interference due to a Fabry Perot cavity The inter-reflector spacing determines the phase of the transmitted energy For maximum constructive interference For maximum destructive interference

6. Fabry Perot cavity based spectrometer For an inter reflector spacing of, the transmitted radiation will add constructively at Broadband incident radiation Narrowband transmitted radiation

7. Broadband incident radiation Narrowband transmitted radiation wavelength amplitude λ0λ0 Tunable Fabry Perot cavity based spectrometer

8. Practical tunable Fabry Perot cavity Support layer Reflecting mirrors Metal electrodes Provides mechanical support Transparent to incident radiation Effect electrostatic actuation Form Fabry Perot cavity

9. Design Considerations Optical transmission through support layer –Investigated by measurements Mechanical displacement of support layer –Investigated by multiphysics FEM simulations Mechanical strength of support layer –Investigated by multiphysics FEM simulations Flatness of reflecting mirror during deflection –Investigated by multiphysics FEM simulations

10. Optical transmission through support layer Optical transmission through the support layer is to be measured The complex permittivity of the support material has been extracted using Variable angle spectrometery

11. Different designs Corrugated support structure to improve flatness Flat support structure

12. Mechanical displacement of support layer FEM multiphysics simulations

13. Mechanical displacement of corrugated support layer FEM multiphysics simulations Top view of deflected top mirror Top view of deflected support layer

14. Flatness of displaced reflecting mirror (corrugated structure) FEM multiphysics simulations

15. Mechanical displacement of flat support layer Top view of deflected top mirror Top view of deflected support layer FEM multiphysics simulations

16. Flatness of displaced reflecting mirror (flat structure) FEM multiphysics simulations

17. Tunable Fabry Perot cavity based microspectrometer (computer generated model showing support layer) Mechanical displacement Mises stresses due to displacement

18. Tunable Fabry Perot cavity based microspectrometer (computer generated model showing metal surfaces)