Optical waveguide crossing
Keywords
optical, bidirectional
Ports
| Name | Type |
|---|---|
| port 1 | Optical Signal |
| port 2 | Optical Signal |
| port 3 | Optical Signal |
| port 4 | Optical Signal |
Properties
General Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
name Defines the name of the element. | Waveguide Crossing | - | - |
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). | Waveguide Crossing | - | - |
description A brief description of the elements functionality. | Optical waveguide crossing | - | - |
prefix Defines the element name prefix. | WX | - | - |
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 |
|---|---|---|---|
configuration Defines the bidirectional or unidirectional element configuration. | bidirectional | - | [bidirectional, unidirectional |
Waveguide/Mode 1 Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
orthogonal identifier 1 The first identifier used to track an orthogonal mode of an optical waveguide. For most waveguide, two orthogonal identifiers '1' and '2' are available (with the default labels 'TE' and 'TM' respectively). | 1 | - | [1, +∞) |
label 1 The label corresponding to the first orthogonal identifier. | TE | - | - |
transmission 1 The transmission corresponding to the first orthogonal identifier. | 1 | - | [0, 1] |
reflection 1 The reflection corresponding to the first orthogonal identifier. | 0 | - | [0, 1] |
cross talk 1 Power crosstalk coefficient from orthogonal identifier 1 into each adjacent port. | 0 | - | [0, 0.5] |
crosstalk phase 1 Phase shift applied to the crosstalk coupling for orthogonal identifier 1, specified in radians. A typical default is pi/2. | 1.570796327 | rad | (-∞, +∞) |
Waveguide/Mode 2 Properties
| Name | Default value | Default unit | Range |
|---|---|---|---|
orthogonal identifier 2 The second identifier used to track an orthogonal mode of an optical waveguide. For most waveguide, two orthogonal identifiers '1' and '2' are available (with the default labels 'TE' and 'TM' respectively). | 2 | - | [1, +∞) |
label 2 The label corresponding to the second orthogonal identifier. | TM | - | - |
transmission 2 The transmission corresponding to the second orthogonal identifier. | 1 | - | [0, 1] |
reflection 2 The reflection corresponding to the second orthogonal identifier. | 0 | - | [0, 1] |
cross talk 2 Power crosstalk coefficient from orthogonal identifier 2 into each adjacent port. | 0 | - | [0, 0.5] |
crosstalk phase 2 Phase shift applied to the crosstalk coupling for orthogonal identifier 2, specified in radians. A typical default is pi/2. | 1.570796327 | rad | (-∞, +∞) |
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] |
diagnostic size The number of frequency points used when calculating the filter frequency response. | 1024 | - | [2, +∞) |
Results
| Name | Description |
|---|---|
| diagnostic/response #/transmission | The complex transmission vs. frequency corresponding to the ideal and designed filter. |
| diagnostic/response #/gain | The gain vs. frequency corresponding to the ideal and designed filter. |
| diagnostic/response #/error | Mean square error comparing the frequency response of the designed filter implementation with the ideal frequency response. |
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Implementation Details
The Waveguide Crossing element models the intersection of two optical waveguides, and accounts for transmission, reflection, and crosstalk between the ports. The crosstalk term is split into a coefficient and a phase, with a default value of π/2, which ensures orthogonality to the signal in the through path to minimize interference.
These coefficients are set as power coefficients for each mode using the properties specified above.
The field at each port is calculated as a linear combination from all ports, as follows.
$$\begin{bmatrix}E_1\\E_2\\E_3\\E_4\end{bmatrix}=\begin{bmatrix}r & cr\cdot e^{j\phi} & cr\cdot e^{j\phi} & t\\cr\cdot e^{j\phi} & r & t & cr\cdot e^{j\phi}\\cr\cdot e^{j\phi} & t & r & cr\cdot e^{j\phi}\\t & cr\cdot e^{j\phi} & cr\cdot e^{j\phi} & r\end{bmatrix}\begin{bmatrix}E_1\\E_2\\E_3\\E_4\end{bmatrix}$$
Where:
- \(r\) is the amplitude reflection coefficient
- \(t\) is the amplitude transmission coefficient
- \(cr\) is the amplitude crosstalk coefficient
- \(\phi\) is the crosstalk phase.
For example, the electric field at Port 3 is given by:
$$E_3 = r\cdot E_3 + t\cdot E_2 + cr\cdot e^{j\phi}\cdot E_1 + cr\cdot e^{j\phi}\cdot E_4$$
Important: This element does not enforce passivity; It only checks that the specified power coefficients sum to 1.0 or less. It does not validate whether the amplitude–phase relationships form a physically realizable or unitary scattering matrix . You must ensure that the chosen coefficients correspond to a passive device and do not violate power conservation.