This thermally tunable ring resonator model is built based on component-level simulation results. Note that this model is designed for demonstration purposes. Several component-level simulations will be launched from INTERCONNECT through Lumerical automation API in order to demonstrate the complete workflow. All the associated files can be found in the LCML_resource folder in the lcml_ring_tunable_1550 sub-folder from the download page.
Example Test File
thermally_tunable_ring_resonator.icp (788.7 KB)
User Guide
lcml_ring_tunable_1550 (rr)
LCML: ring resonator with thermal control.
Ports
| Name | Type |
| ele_t1 | Electrical Signal |
| ele_t2 | Electrical Signal |
| opt_in | Optical Signal |
| opt_thru | Optical Signal |
| opt_drop | Optical Signal |
| opt_add | Optical Signal |
CML/Process
| Name | Default value | Default unit | Range |
| process | foundry_A | -- | [foundry_A, foundry_B] |
CML/Ring
| Name | Default value | Default unit | Range |
| radius | 10 | um* *std. unit is m |
[5, 100] |
| wg_width | 0.5 | um* *std. unit is m |
[0.4, 0.8] |
| coupling_gap | 0.2 | um* *std. unit is m |
[0, 0.5] |
| coupling_length | 0 | um* *std. unit is m |
[0, 20] |
| hangover_length | 20 | um* *std. unit is m |
[5, 100] |
Model Development
Overview
The subcircuit of the thermally tunable ring resonator is shown below:
| Element | Representation |
| WG_Hangover_X (1-4) | Straight waveguides between ports and coupling regions |
| WG_Passive_X (1-2) | Bend waveguides in the ring |
| Coupler_X (1-2) | Directional coupler |
| Thermal_Tuning_X (1-2) | Thermal tuning |
The input parameters of the ring are listed in the table below:
| Name | Kind | Type | Value (default) | Unit | Category |
| process | NonQuantity | ComboChoice | foundry_A | Process | |
| radius | Distance | Number | 10 | Ī¼m | Ring |
| wg_width | Distance | Number | 0.5 | Ī¼m | Ring |
| coupling_gap | Distance | Number | 0.2 | Ī¼m | Ring |
| coupling_length | Distance | Number | 0 | Ī¼m | Ring |
| hangover_length | Distance | Number | 20 | Ī¼m | Ring |
Description of the input parameters
The āprocessā parameter is created to describe the information regarding the fabrication process, e.g., silicon thickness, etch depth, doping, etc. In this example, the element supports two foundry processes, namely foundry_A and foundry_B, and their information are summarized in the table below. Internally, these information are stored in two script files: foundry_A.lsf and foundry_B.lsf in the LCML Destination folder (ā¦/lib_data/ring_thermal/). Users can edit these files to define the specific foundry process that they will use.
| Parameter | foundry_A | foundry_B |
| Silicon full height | 220 nm | 250 nm |
| Silicon slab height | 70 nm | 90 nm |
| N doping concentration | 5e+17 cm^-3 | 5e+17 cm^-3 |
| P doping concentration | 7e+17 cm^-3 | 7e+17 cm^-3 |
āradiusā: radius of the ring
āwg_widthā: width of the rib waveguide.
ācoupling_gapā: gap between the straight waveguide and the ring
ācoupling_lengthā: length of the coupling waveguides in parallel
āhangover_lengthā: distance between the port and the coupling region
Model details and parameter extraction
This ring element is a PCell. As the ring property changes, the model will automatically detect if the required data exist. If not, the model will:
- Launch the component simulation tools
- Build the simulation based on template files
- Run the simulation
- Extract the required information
- Update the internal element properties
The complete workflow is controlled by scripts. Specifically, we use the [Lumerical automation API] (https://kb.lumerical.com/en/index.html?ref_scripts_interoperability.html) to drive the component tools from INTERCONNECT. The top-level setup scripts of the compound element are shown below.
# Process definition
process_filename = %local path% + '/lib_data/ring_thermal/' + process + '.lsf';
feval(process_filename);
# Hangover waveguide
selectpartial("WG_Hangover");
set("length",hangover_length+coupling_length/2);
lsf_filename = %local path% + '/lib_data/ring_thermal/rib_waveguide_passive_straight.lsf';
feval(lsf_filename);
set("frequency", f);
set("effective index 1", neff);
set("loss 1", loss);
set("group index 1", ng);
set("dispersion 1", disp);
# Couplers
selectpartial("Coupler");
lsf_filename = %local path% + '/lib_data/ring_thermal/coupler.lsf';
feval(lsf_filename);
set("load from file", 1);
set("s parameters filename", s_filename);
# Passive waveguides (bend) in the ring
selectpartial("WG_Passive");
set("length",pi*radius+coupling_length/2);
lsf_filename = %local path% + '/lib_data/ring_thermal/rib_waveguide_passive_bend.lsf';
feval(lsf_filename);
set("frequency", f);
set("effective index 1", neff);
set("loss 1", loss);
set("group index 1", ng);
set("dispersion 1", disp);
# Thermal tuning
selectpartial("Thermal_Tuning");
set("length",pi*radius);
In this particular example, the template project files and script files are located in the LCML installation folder (ā¦/lib/ring_thermal). Two sets of pre-existing data are also provided for the model:
- process=foundry_A, wg_width=0.5 um, radius=5 um, coupler_gap=0.2 um, coupler_length=0 (default)
- process=foundry_B, wg_width=0.4 um, radius=7.5 um, coupler_gap=0.1 um, coupler_length=2 um
Waveguides
The straight and bend waveguides are based on the primitive Straight Waveguide model. Check the project file rib_waveguide.lms and associated script files rib_waveguide_passive_bend.lsf and rib_waveguide_passive_straight.lsf in MODE Solutions.
Directional couplers
The directional couplers are based on the primitive Optical N port S-Parameter element. Check the project file coupler.fsp and associated script files coupler.lsf, write_s_parameters.lsf, and scale_s_parameters.lsf in FDTD Solutions. Note that only the amplitudes of the S parameters are extracted to represent the coupling coefficient. The optical delay of the directional coupler are represented by the waveguide elements.
Thermal tuning
The thermal tuning is described by the Optical Modulator Measured elements, using the same effective index table as in the Thermally tunable waveguide element.
Test
Download the simulation file thermally_tunable_ring_resonator.icp from the top of this page. In this simulation file, the thermally tunable ring resonator is measured by an Optical Network Analyzer (ONA). The figure below plots the through port spectra at driving voltage of 0 V and 1.2 V, respectively.
Change some of the ring properties. The element will automatically launch several simulations in MODE Solutions and FDTD Solutions.
