The phase_shifter_thermal photonic model was created to model thermo-optic phase shifters. It supports the creation of models which are parameterized by phase shifter length, as well as temperature dependence. It also supports the creation of thermo-optic phase shifters which include multiple (two) heaters applied to the same waveguide. This photonic model is well-suited to model phase shifters which use either resistive or doped heaters.
This model supports statistical modeling. Users can choose an arbitrary number of statistical parameters and define their influence on the effective and group indices of the waveguide as well as the insertion loss and thermal modulation efficiency of the phase shifter. For information on statistical CMLs, see Statistical CMLs.
Lumfoundry Templates: Thermal Phase Shifter, Thermal Phase Shifter (Statistical)
Quality Assurance Test: phase_shifter_thermal QA
Statistical Modeling Support: neff, ng, IL, Ppi
Supported Parameters: phase shifter length
Tuning Support: Power for π phase shift, Insertion loss
Interoperability with Cadence Virtuoso:
- Circuit design flows using INTERCONNECT model: Yes.
- Circuit design flow using photonic Verilog-A model: Yes (no statistical modeling).
Model Information
- This model assumes thermal bandwidth to be constant over all bias range.
- This model supports dual mode of operation.
- The main required data to build a thermal phase shifter model are summarized in the table below.
Main required data |
Phase shifter waveguide default length. |
Number of modes supported. |
Current (I) - Voltage (V) characteristics of the heater OR Resistance of the heater. |
Insertion loss at zero bias voltage. |
Power required to achieve pi phase shift. |
Electrical Equivalent Circuit for INTERCONNECT model
INTERCONNECT model can be used in the Cadence Virtuoso platform for PIC (photonic integrated circuit and EIC (electronic integrated circuit) co-design and co-simulation. When running a Spectre-INTERCONNECT electro-optical co-simulation, the electrical loading effect of the thermal phase shifter can be modeled by an electrical equivalent circuit that is physically instantiated in Spectre. Users can create an electrical equivalent circuit for the thermal phase shifter by running CML Compiler with the “--interconnect_virtuoso” command line option.
The above figure shows the use of the electrical equivalent circuit and the optical INTERCONNECT model (i.e., PSTH_O) for co-simulation case. The electrical equivalent circuit is a resistor model that is described by the source IV data or a fixed resistance, and it has unlimited electrical bandwidth. The thermal transient bandwidth of the device is defined by an electrical low pass filter (LPF) inside the PSTH_O element. For co-simulation, Spectre simulates the electrical equivalent model for its electrical characteristics; while INTERCONNECT simulates the optical INTERCONNECT model.
Electrical Equivalent Circuit for Photonic Verilog-A model
Photonic Verilog-A models is compatible with Cadence Virtuoso design platform and its Spectre simulator. When simulating the photonic Verilog-A model for a thermal phase shifter element using Spectre, the electrical equivalent circuit and the photonic model are both implemented inside the compiled Verilog-A thermal phase shifter element as shown in the figure below. Spectre simulates both the electrical equivalent circuit for the thermal phase shifter’s electrical characteristics and the photonic thermal phase shifter model for its optical characteristics. The Verilog-A model for an EAM element can be generated through CMLC by executing it with --veriloga_virtuoso command line option.