In the Traveling Wave Laser Model (TWLM), a distribution of injected current can be set either by loading current distribution data file, or by directly setting a current distribution table. This article will detail how to set current distribution in TWLM.
Regardless of whether the table is directly inputted, or loaded from a .dat file, the current distribution table is a two-column table. The first column in the current distribution table is the normalized position along the length of the structure, and the second column is the unitless weight to be assigned to the current injected at that position. The position values must be normalized between 0 and 1. For example, the figure below corresponds to the values defined in the following current distribution table.
|
Normalized position |
Weights (arb. units) |
|---|---|
|
0 |
0 |
|
0.249 |
0 |
|
0.251 |
4 |
|
0.749 |
4 |
|
0.751 |
0 |
| 1
|
0 |
From the current distribution table, the actual position is obtained by multiplying the normalized position by the length of TWLM. The weights are then linearly interpolated at the middle of each TWLM segment. The weights will be automatically normalized (if not done by the user), so that the integral of weights is equal to 1. The injection current applied to each section is given by:
$$
I_i = I \frac{W_i}{\sum_{i=1}^{N} W_i}
$$
The sum of the injection current applied to each section is equal to the total injection current \(I\).
$$
\sum_{i=1}^{N} I_i = I
$$
The following figure shows the simulated normalized current injection weights for a TWLM length of 1000 µm.
See Also