modulates an optical signal depending on electrical signal
Keywords
electrical, optical, unidirectional
Ports
| Name | Type |
|---|---|
| input | Optical Signal |
| modulation 1 | Electrical Signal |
| modulation 2 | Electrical Signal |
| output | Optical Signal |
Properties
General Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
name Defines the name of the element. |
Mach-Zehnder Modulator | - | - |
|
annotate Defines whether or not to display annotations on the schematic editor. |
true | - | [true, false] |
|
enabled Defines whether or not the element is enabled. |
true | - | [true, false] |
|
type Defines the element unique type (read only). |
Mach-Zehnder Modulator | - | - |
|
description A brief description of the elements functionality. |
modulates an optical signal depending on electrical signal | - | - |
|
prefix Defines the element name prefix. |
MZM | - | - |
|
model Defines the element model name. |
- | - | - |
|
library Defines the element location or source in the library (custom or design kit). |
- | - | - |
|
local path Defines the local path or working folder $LOCAL for the element. |
- | - | - |
|
url An optional URL address pointing to the element online help. |
- | - | - |
Standard Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
modulator type Defines whether the modulator is a single drive or a dual drive modulator. |
dual drive | - | [dual drive, balanced single drive, unbalanced single drive |
|
dc bias source Defines whether to use an internal or external source for bias voltage. |
internal | - | [internal, external |
|
bias voltage 1 The bias voltage for the first arm of the modulator. |
0 | V | (-∞, +∞) |
|
bias voltage 2 The bias voltage for the second arm of the modulator. |
2 | V | (-∞, +∞) |
|
pi dc voltage Defines the modulator Vπ DC voltage. |
4 | V | (-∞, +∞) |
|
pi rf voltage Defines the modulator Vπ AC voltage. |
4 | V | (-∞, +∞) |
|
extinction ratio Defines the extinction ratio. |
30 | dB | [0, +∞) |
|
insertion loss Defines the insertion loss (attenuation). |
6 | dB | [0, +∞) |
|
phase shift Lower arm additional phase shift. |
0 | rad | (-∞, +∞) |
Waveguide Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
modes List of optical mode labels supported by the element. |
TE,TM | - | - |
Diagnostic Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
|
run diagnostic Enables the frequency response of the designed filter implementation and the ideal frequency response to be generated as results. |
false | - | [true, false] |
|
start voltage 1 The lower voltage limit for the calculated graph. |
0 | V | (-∞, +∞) |
|
stop voltage 1 The upper voltage limit for the calculated graph. |
8 | V | (-∞, +∞) |
|
number of points 1 The number of points of the calculated graph |
200 | - | [2, +∞) |
|
start voltage 2 The lower voltage limit for the calculated graph. |
0 | V | (-∞, +∞) |
|
stop voltage 2 The upper voltage limit for the calculated graph. |
8 | V | (-∞, +∞) |
|
number of points 2 The number of points of the calculated graph |
200 | - | [2, +∞) |
Results
| Name | Description |
|---|---|
| diagnostic/power | The normalized intensity vs. voltage at port 1 and port 2. |
| diagnostic/angle | The angle vs. voltage at port 1 and port 2. |
====================================
Implementation Details
This element implements an analytical model for a Mach-Zehnder Modulator (MZM). In this model, a voltage and a bias are applied to the arms of the modulator. The phase shift applied to each arm is given by:
$$ϕ^{(i)}=π\left(\frac{V^{(i)}}{V_{RF}^π}+\frac{V_{bias}^{(i)}}{V_{DC}^π}\right)$$
where \(V^{(i)}\) is the voltage and \(V_{bias}^{(i)}\) is the bias applied to arm \(i\), and \(V_{RF}^π\) and \(V_{DC}^π\) are the "pi rf voltage" and "pi dc voltage" values. respectively. The transmission is determined by the difference in the phase shifts applied to the arms, with a minimum transmission occurring with a phase difference of \(\pi\). The transmission spectrum is further parameterized by the "insertion loss" and "extinction ratio" properties. A plot of normalized transmission from an MZM element with no bias voltages and no voltage applied to arm 2 is shown below:
The "modulator type" can be set as:
- "Dual drive", where the voltages applied to the two arms are independent,
- "Balanced single drive", where the opposite of the voltage applied to the first arm is applied to the second arm, and
- "Unbalanced single drive", where a voltage is applied to the first arm but no voltage is applied to the second arm.
The "dc bias source" property determines how the voltage bias is applied to each of the arms. If it is set to "internal", the bias is determined by the "bias voltage 1" and "bias voltage 2" properties. If it is set to "external", two electrical ports (bias 1 and bias 2) are added to the element, and the bias is set using the signal at these ports.
Diagnostic
An element diagnostic can be run by setting the "run diagnostic" property to "true" and running the simulation. The normalized transmission and phase of the MZM will be determined for the range of voltages from "start voltage 1" to "stop voltage 1" (for arm 1) and from "start voltage 2" to "stop voltage 2" (for arm 2). This is a useful way of viewing the transmission properties of this element for a full range of voltages without running multiple simulations.
Similar elements
- MZM Measured: The Measured MZM element uses a data table to determine the relationship between the voltage applied to the arms and the transmission. The table can include data for the change in real and imaginary effective index or absorption and phase shift. The MZM Measured element is commonly used along with data from CHARGE or MODE simulations (see the PN Depletion Phase Shifter example).
Examples
The MZM element is used in the following example:
For the implementation details of the traveling wave electrode, please see the application example PIN Mach-Zehnder for more information.
References
See for the following reference for a description of the standard properties of the MZM:
- J.C. Cartledge, C. Rolland, S. Lemerle, A. Solheim, "Theoretical performance of 10 Gb/s Lightwave Systems using a III-V Semiconductor Mach-Zehnder Modulator," IEEE PTL Vol 6, No. 2, 282-284 (1994)
- J.C. Cartledge, "Performance of 10 Gb/s Lightwave Systems Based on Lithium Niobate Mach-Zehnder Modulators with Asymmetric Y-Branch WAveguides," IEEE PTL Vol 7, No. 9, 1090-1092 (1995)