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Tunable Ring Switch - Lumfoundry Template

A fixed tunable ring switch with independent thermal tuners and shared electrical phase shifters for operation in C-band.

Note: For legacy data format (2022 R2.4 and older) please visit following link:

Tunable Ring Switch - Lumfoundry Template (Legacy)

Template: rs_strip_te_c

Photonic Model: tunable_ring_switch

Quality Assurance Test: tunable_ring_switch_QA

Parameters: None.

Interoperability with Cadence Virtuoso:

  • Circuit design flows using INTERCONNECT model: Yes.
  • Circuit design flow using photonic Verilog-A model: No.

Modeling Data

The source data template for a tunable ring switch element can divided into two sections.

  1. For new users (continue with the following section: Basic Data Requirement)
  2. For advanced users (continue with section: Complete Data Requirement)

The tunable ring switch template can be used to create a very advanced compact model for a custom tunable ring switch . The template contains a lot of different modeling data to create an accurate model. However, not all these data need to be updated by the user. The fastest/ simplest way to modify the template data and create a custom compact model would be to only update the values of the data listed in the 'basic data requirement section' below, while all rest of the data (which is illustrated in detail in subsequent sections) can be left at their default value.

Note: Advanced users please jump start with Complete Data Requirement (for advanced users) section.

Basic data requirement section (for new users)

The basic or minimum data required to build the tunable ring switch model is described below.

general

"general" is a struct with following fields:

Field Type Description
description string A string containing a brief description of the model, which will be displayed to the end user.
notes cell

A cell array that provides model notes which will be displayed to the end user. Each element of the cell is a struct with the fields:

  • property: String with the name of the note.
  • value: String with the contents of the note.
time_domain_req_note

boolean

A flag to whether or not add a note in the compact model quoting the minimum sampling rate required for accurate time domain simulation

ports

"ports" is a struct with following fields:

Field Type Description

opt_1

 struct with fields described in table below port definition corresponding to the in-through optical ports

opt_2

opt_3

 port definition corresponding to the add-drop ports

opt_4 

ele_an

 port definition corresponding to the anode and cathode for the electrical tuner

ele_cat

th_neg_top

port definition corresponding to the positive and negative nodes of the top thermal tuner

th_pos_top

th_neg_bot

port definition corresponding to the positive and negative nodes of the bottom thermal tuner.

th_pos_bot

Each struct above consists of following fields:

Field Type Description
name string The name of the port, which will be visible to the end user. This name should be consistent with the name that will be used for netlisting.
dir string The directionality of the port, either "Input", "Output", or "Bidirectional"
pos string

The side of the model which the port will be displayed on, either "Left", "Right", "Top", or "Bottom"
order number

The order at which the port is listed in a netlist.

model_data

"model_data" is a struct with following fields:

Field Type Description
electrical_tuner_data

struct with fields described in electrical_tuner_data table

Data required for modeling the electrical tuner.
th_eq_ckt_data

struct

Thermal equivalent circuit described by either current (Amp) versus bias voltage (V) characteristic of the heater for the default phase shifter length with required field of:

  • voltage: Bias voltage data points as matrix.
  • current: Current data points as a matrix.

The IV data are linearly interpolated to obtain the electrical behavior. 

or resistance (\(\Omega)\) of the heater for the default length of the phase shifter with required field of:

  • R_thermal_tuner: Heater resistance as a single number.
Note:
  • Using a linear model is suitable for resistive heaters, but for voltage-dependent models an IV characteristic should be used instead.
  • If IV data is provided, it will take preference over R_thermal_tuner data 
  • If IV data is provided:
    • At least two bias points must be provided. 
    • Bias voltage and current values must be positive. 
    • These data will be used instead of a resistance value, if provided. 
    • The I*V values must fall within the range of power values provided in thermal_tuner_data. 

electrical_tuner_data

Note: For a ring without electrical tuner, this struct should not be provided.

Field Type Description

bandwidth_data

 struct

The 3-dB cutoff frequency (Hz) of the electrical modulator as a function of bias voltage (V). The required fields are:

  • bandwidth: 3-dB cutoff frequency (Hz) data points as a matrix.
  • voltage: Bias voltage (V) given by \(V_{bias} = V_{anode} - V_{cathode}\) data points as a matrix.

FOMs

"FOMs" is a struct with fields below. This data is required for CML Compiler to run quality-assurance tests on the final model. It is also optionally used by CML Compiler to fine-tune the internal model to provide the expected behavior.

If the source physical data provided for the model is not consistent with figures of merit(FOMs) provided (meaning the actual FOM values resulting from physical parameters differ from provided FOM data), the model can tune the provided physical data to match the FOMs to the provided values. For more information, see Tuning Active Compact Models.

Field Type Description

IL

struct with fields described in table below

The overall insertion loss (dB) of the ring modulator at through port at resonance.

Note: 

  • Tuning for IL, IL_drop, ER and Q are tied together. If tuning is enabled for any of these FOMs, the model automatically tunes for the rest. 
  • If through port IL and ER are both present, the model will be tuned to IL at through port and ER value will be ignored. 

IL_drop

struct with fields described in table below

The overall insertion loss (dB) of the ring modulator at drop port at resonance.

Note:

  • This value is required for a double-bus ring modulator. 
  • Tuning for IL, IL_drop, ER and Q are tied together. If tuning is enabled for any of these FOMs, the model automatically tunes for the rest.

FSR

 struct with fields described in table below

The free spectral range (m) of the ring modulator.
mod_eff

struct with fields described in table below

Overall electro-optic modulation efficiency (m/V) of the ring modulator within the voltage range described by "ref1" and "ref2" in the struct. 
mod_eff_thermal

struct with fields described in table below

Overall thermo-optic modulation efficiency (m/W) of the ring modulator for input power range described by "ref1" and "ref2" in the struct which should be within the range of I*V values provided

Note: For a ring without thermal tuner, this parameter should not be provided.
Q

struct with fields described in table below

The quality factor (m/m) of the ring modulator near resonance.

Note: Tuning for IL, IL_drop, ER and Q are tied together. If tuning is enabled for any of these FOMs, the model automatically tunes for the rest. 
ER  

struct with fields described in table below

The extinction ratio (dB) of the ring modulator at resonance provided as a struct.

Note:

  • Tuning for IL, IL_drop, ER and Q are tied together. If tuning is enabled for any of these FOMs, the model automatically tunes for the rest. 
  • If through port IL and ER are both present, the model will be tuned to IL at through port and ER value will be ignored. 
resonant_wavelength
 

struct with fields described in table below

The resonant wavelength (m) of the ring modulator at a temperature of 300K with no applied electrical or thermal phase shift.

Each struct above consists of the following fields:

Field Type Description

value

number

The nominal value for the FOM in SI units.

tuning

boolean

A flag to enable or disable tuning for the FOM.
min

number

Minimum allowed value in SI unit if visible_to_user is set to True.
max

number

Maximum allowed value in SI unit if visible_to_user is set to True.
ref1 (if applicable)

number

 Point(s) at which the nominal FOM was measured. This can be voltage or power data points depending on the FOM definition.
ref2 (if applicable)
 

number

 

Complete data requirement (for advanced users)

The complete data section provides a complete reference of data supported by the tunable ring switch model including the basic required data described in the previous section. The description of all the fields in the tunable ring switch source data template are described below.

general

"general" is a struct with following fields:

[[snippet||11549514081811]]

time_domain_req_note

boolean

A flag to whether or not add a note in the compact model quoting the minimum sampling rate required for accurate time domain simulation

ports

"ports" is a struct with following fields:

[[snippet||11726991270675]]

Each struct above consists of following fields:

[[snippet||11549759363603]]

parameters

"parameters" is a struct with following fields:

[[snippet||11644750903571]]

model_data

"model_data" is a struct with following fields:

[[snippet||11727362048659]]

Structs listing mode properties for different waveguide sections consist of following fields:

[[snippet||11653970537235]]

FOMs

"FOMs" is a struct with fields below. This data is required for CML Compiler to run quality-assurance tests on the final model. It is also optionally used by CML Compiler to fine-tune the internal model to provide the expected behavior.

If the source physical data provided for the model is not consistent with figures of merit(FOMs) provided (meaning the actual FOM values resulting from physical parameters differ from provided FOM data), the model can tune the provided physical data to match the FOMs to the provided values. For more information, see Tuning Active Compact Models.

[[snippet||11727925083923]]

Each struct above consists of the following fields:

[[snippet||11653867902995]]

QA

"QA" is a struct with following fields:

[[snippet||11653366721555]]

 

 

Associated files

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