finesse.analysis.actions.lti.FrequencyResponse3

Overview

class finesse.analysis.actions.lti.FrequencyResponse3(f, inputs, outputs, *, name='frequency_response3')[source]

Bases: Action

Computes the frequency response of a signal injected at an optical port at a particular optical frequency. This differs from FrequencyResponse in the way the inputs and outputs are prescribed. For FrequencyResponse3 you specify optical input nodes and optical output nodes.

This action does not alter the model state. This action will ignore any currently definied signal generator elements in the model.

Produces an output transfer matrix from each HOM at a particular frequency and optical node to some other optical node and frequency. The shape of the output matrix is:

[frequencies, outputs, inputs, HOMs, HOMs]

It should be noted that when exciting a lower signal sideband frequency it will actually return the operator for propagating the conjugate of the lower sideband. This is because FINESSE is internally solving for the conjugate of the lower sideband to linearise non-linear optical effects.

To inject into mechanical and electrical nodes please see FrequencyResponse and FrequencyResponse4. To readout mechanical and electrical nodes please see FrequencyResponse and FrequencyResponse2.

Parameters
farray, double

Frequencies to compute the transfer functions over

inputsiterable[tuple[str or Node, Frequency]]

Optical node and frequency tuple to inject at. A symbolic reference to the model’s fsig.f parameter should always be used when defining a frequency to look at.

outputsiterable[tuple[str or Node, Frequency]]

Optical node and frequency tuple to measure output at. A symbolic reference to the model’s fsig.f parameter should always be used when defining a frequency to look at.

namestr, optional

Solution name

Examples

It is advisable to use always use a reference to the symbolic reference to the signal frequency model.fsig.f.ref instead of a fixed number incase it changes. This action will look for an initial frequency bin of X Hz to track during the frequency response analysis. A symbolic reference will always ensure the right bin is used, in cases such as looking at RF signal sidebands, 10e6+model.fsig.f.ref and 10e6-model.fsig.f.ref will always look at the upper and lower signal sideband around the +10MHz sideband.

>>> import finesse
>>> from finesse.analysis.actions import FrequencyResponse3
>>> model = finesse.script.parse('''
... l l1
... bs bs1 R=1 T=0 xbeta=1e-6 ybeta=1e-9
... readout_dc A
... link(l1, bs1, A)
... fsig(1)
... modes(maxtem=1)
... gauss g1 l1.p1.o w=1m Rc=inf
... ''')
>>> sol = model.run(
...     FrequencyResponse3(
...         [1, 10, 100],
...         [
...             ('bs1.p2.o', +model.fsig.f.ref),
...             ('bs1.p2.o', -model.fsig.f.ref)
...         ],
...         [
...             ('A.p1.i', +model.fsig.f.ref),
...             ('A.p1.i', -model.fsig.f.ref)
...         ]
...     )
... )