The fiber class models the transmission of an optical signal along a fiber.
For this the non linear Schrödinger equation is solved numerically by the Fourier-Split-Step-Method:
$$ \frac{\partial A_x }{\partial z} + \beta_{1x} \frac{\partial A_x }{\partial t} + \frac{j\beta_{2} }{2} \frac{\partial A_x }{\partial t^2} -\frac{\beta_{3} }{6} \frac{\partial A_x }{\partial t^3} + \frac{\alpha }{2}A_x = i\gamma\left( |A_x|^2 + \frac{2}{3}|A_y|^2 \right)A_x$$ $$ \frac{\partial A_y }{\partial z} + \beta_{1y} \frac{\partial A_y }{\partial t} + \frac{j\beta_{2} }{2} \frac{\partial A_y}{\partial t^2} - \frac{\beta_{3} }{6} \frac{\partial A_y }{\partial t^3} + \frac{\alpha }{2}A_y = i\gamma\left( |A_y|^2 + \frac{2}{3}|A_x|^2 \right)A_y$$
Both polarisations and their interaction are calulated. You cannot "switch" one polarisation off, to reduce the calculation time.
pypho_fiber.__init__(glova, fibertype, D, S, gamma, alpha, l, birefarray, phi_max)
Instantiation and parameter setting.
| Parameter | Type | Description |
|---|---|---|
glova |
instance | Global parameters |
fibertype |
string | Sets default values for typical fiber types:'SSMF': D=17, S=17, alpha=0.2 |
D |
float | Dispersion coefficient at the center frequency pypho_setup.f0 in $\frac{\text{ps}}{\text{nm km}}$. |
S |
float | Dispersion slope coefficient in $\frac{\text{ps}}{\text{nm}^{2} \text{km}}$. |
gamma |
float | Nonlinear coefficient $\gamma$ in $\frac{1}{\text{W km}}$. |
alpha |
float | Fiber attenuation $\alpha$ in $\frac{\text{dB}}{\text{km}}$. |
l |
float | Fiber length in km. |
birefarray |
list | This list describes the polarisation properties of the fiber. The list must include a rotation angle birefarray[].angle the fiberlength birefarray[].z_point and a $\Delta\beta_1 = \beta_{1x} - \beta_{1y}$ value birefarray[].delta_beta valid to the next of the birefarray[].z_point. |
| Output | Type | Description |
|---|---|---|
| User defined variable | pypho_fiber.pypho_fiber |
pypho_fiber.__call__(E, fibertype (optional), D (optional), S (optional), ...
...gamma (optional), alpha (optional), l (optional), ...
...birefarray (optional), phi_max (optional))
| Parameter | Type | Description |
|---|---|---|
E |
list | List in which the optical data and noise signal are defined. Read here about data signal and noise representation |
| Optional paramter | As defined above |
| Output | Type | Description |
|---|---|---|
| User defined variable | list | Returns a list in which the optical data and noise signal are defined. Read here about data signal and noise representation. |