In this example, a ring resonator connecting an input waveguide to an output waveguide is designed to
re-direct signal content at a frequency of 193.1 THz, corresponding to a wavelength of 1552.52 nm - the center of
the telecommunications c-band, to the drop waveguide. The design goals are to first determine where the as-specified
structure operates, and then determine how much the refractive index of the ring would have to be modified to tune
the device to drop the channel at 193.1 THz.
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Step 1: Construct the ring resonator in the layout editor
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The layout editor shows all of the simulation objects, and their positioning. Different classes of objects (physical primitives, radiation sources, monitors) are color coded for easy identification. Objects can be dragged, dropped, and resized with simple mouse movements.
- blue regions denote dielectric regions
- orange regions show the extents of the computation area, bounded by absorbing (PML) boundary conditions
- yellow lines show transmission monitors; yellow X's show time measurement monitors
- window at the bottom shows the script window, where customized commands and analysis can be performed
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Step 2: Select the waveguide mode to be launched into the input waveguide
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The embedded mode solver allows the user to inject either 2D or 3D guided modes into the simulation volume - including metal
waveguide modes, surface plasmon modes, anti-resonant modes, and the more conventional dielectric waveguide modes.
- select the number of modes to be solver for
- view the mode profile for different field components
- pick the mode of interest - whether TE or TM polarized - and select it for injection with the click of a button
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Step 3: Determine where the ring resonator is operating
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Integrated analysis routines facilitate data analysis and visualization. Choose from drop-down menus which
monitor you wish to analyze, and the field component of interest.
- line plot shows the time signal measured in the drop waveguide
- each time the radiation cycles around the ring, a pulse is coupled into the output waveguide
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- use built-in analysis routines to look at the frequency response of the time-signal via fast Fourier transform
- simple mouse movements allow us to zoom in to frequencies around 193.1 THz
- the line plot shows that, in the drop waveguide where the time data was collected, very little signal at 193.1 THz is received, but that at 189.2 THz maximum signal is dropped
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Step 4: Visualize the steady-state operation of the ring resonator
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Use frequency-domain monitors to record the steady-state / continuous-wave (CW) response of interest. Multiple steady-
state responses can be determined in a single simulation, saving time over frequency-based solution techniques.
- an area monitor tuned to a frequency of 189.2 THz shows the radiation being efficiently dropped
- the colorbar shows field build-up within the ring, as expected
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- an area monitor tuned to a frequency of 193.1 THz shows the radiation being efficiently transmitted
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Step 5: Tune the resonator to drop the channel at 193.1THz
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The built-in scripting environment can be used to perform parameter sweeps, customize analysis, or automate both simulation and analysis to optimize device performance.
- simulations performed while varying the refractive index of the ring allow us to determine how much
to vary the index of the ring to efficiently drop signal at 193.1THz
- after five easy steps, we see that setting the ring index to 2.856 instead of the original
2.915 results in an effective design for a channel drop filter operating at 193.1THz
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Step 6: Gain operational insight - watch the movie
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