This file is a text file that can be edited using notepad or any other text file editor. It contains the description of the time dependent signals that go into the simulation. Each line in the file is the information relating to a single timestep in the simulation. Note that in this file it is not allowed to put comments.
On each line there is information on:
the optical power (in Watt) going left to right at the "IO Component Left hand side" component in the circuit
the phase (in rad) of the optical field going left to right at the "IO Component Left hand side" component in the circuit
the optical power (in Watt) going right to left at the "IO Component Right hand side" component in the circuit
the phase (in rad) of the optical field going right to left at the "IO Component Right hand side" component in the circuit
for each time dependent source there is a value for the source. The order of the source input is according to the numbering of the time dependent sources.
for a current source this is in Amperes
for a phase modulator this is in rads (at the moment)
The file thus contains a minimum of four columns.
One does not need to provide a time dependent input line for all time steps in the simulation.
The file can be shorter. If it is shorter, the optical input is just zero, the value of the sources stays at the last timedependent input line.
This input file is typically generated by a program written by the user (MATLAB, MathCAD, Octave, Python, Excel (joking)). See also the page Running PHIsim.
An example signals input file is given on the examples page.