240 likes | 501 Views
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. Electromagnetic interference.
E N D
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
Electromagnetic interference • Electromagnetic energy from different sources will interfere when sharing the same space
Electromagnetic interference • Interference depends on the phase of each component Constructive interference
Incident radiation Reflecting surface Reflecting surface Transmitted radiation A Fabry Perot cavity creates multiple sources with different phase from a single source
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
Broadband incident radiation Narrowband transmitted radiation Fabry Perot cavity based spectrometer • For an inter reflector spacing of , the transmitted radiation will add constructively at
Broadband incident radiation amplitude Narrowband transmitted radiation wavelength Tunable Fabry Perot cavity based spectrometer λ0
Practical tunable Fabry Perot cavity • Provides mechanical support • Transparent to incident radiation Support layer Metal electrodes Reflecting mirrors • Effect electrostatic actuation • Form Fabry Perot cavity
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
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
Flat support structure Corrugated support structure to improve flatness Different designs
Mechanical displacement of support layer FEM multiphysics simulations
Top view of deflected support layer Top view of deflected top mirror Mechanical displacement of corrugated support layer FEM multiphysics simulations
Flatness of displaced reflecting mirror (corrugated structure) FEM multiphysics simulations
Top view of deflected support layer Top view of deflected top mirror Mechanical displacement of flat support layer FEM multiphysics simulations
Flatness of displaced reflecting mirror (flat structure) FEM multiphysics simulations
Tunable Fabry Perot cavity based microspectrometer(computer generated model showing support layer) Mises stresses due to displacement Mechanical displacement
Tunable Fabry Perot cavity based microspectrometer (computer generated model showing metal surfaces)