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Lecture 17. Coupling of modes in time. Milos Popovic Mar 13, 2012 ECEN5645. Coupled Mode Theory in Time Model of Ring Filters. Resonator oscillates at natural frequency of chosen resonant mode. Coupled Mode Theory in Time Model of Ring Filters.
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Lecture 17. Coupling of modes in time Milos Popovic Mar 13, 2012 ECEN5645
Coupled Mode Theory in Time Model of Ring Filters • Resonator oscillates at natural frequency of chosen resonant mode M. Popovic (milos@mit.edu)
Coupled Mode Theory in Time Model of Ring Filters • Resonator oscillates at natural frequency of chosen resonant mode • Higher order mode shows radiation loss in dielectric resonators (bending loss here) M. Popovic (milos@mit.edu)
Coupled Mode Theory in Time Model of Ring Filters • Resonator oscillates at natural frequency of chosen resonant mode • Higher order mode shows radiation loss in dielectric resonators (bending loss here) • Absorb loss into a complex frequency variable M. Popovic (milos@mit.edu)
Coupled Mode Theory in Time Model of Ring Filters • Resonator oscillates at natural frequency of chosen resonant mode • Higher order mode shows radiation loss in dielectric resonators (bending loss here) • Absorb loss into a complex frequency variable • Decay rates due to coupling to waveguides M. Popovic (milos@mit.edu)
Coupled Mode Theory in Time Model of Ring Filters • Excite resonator via input waveguide M. Popovic (milos@mit.edu)
Equivalent Circuit • Mapping to electronic filter synthesis (1930s) gives flat-top high-order designs • Filter determined by ring resonances, coupling and losses Ring filter model Equiv. CCT Γ M. Popovic (milos@mit.edu)
Thru In wo wo wo Drop High-order microring channel add/drop filters Third-Order Filter (N=3) • Flat-top filter synthesis calls for coupling resonators with identical resonance frequencies • leads to use of identical rings… M. Popovic (milos@mit.edu)