finesse.analysis.actions.sensing.OptimiseRFReadoutPhaseDC

Overview

class finesse.analysis.actions.sensing.OptimiseRFReadoutPhaseDC(*args, d_dof=1e-10, name='optimise_demod_phases_dc')[source]

Bases: Action

This optimises the demodulation phase of ReadoutRF elements relative to some DegreeOfFreedom or driven Parameter in the model. The phases are optimised by calculating the DC response of the readouts. This Action changes the state of the model by varying the readout demodulation phases. If no arguments are given it will try to automatically optimise any lock element in the model that is using an RF readout with respect to the lock feedback parameter.

Parameters
args

Pairs of DegreesOfFreedom or Parameter and ReadoutRF elements, or pairs of their names. If none are provided OptimiseRFReadoutPhaseDC will automatically search for Lock elements which have ReadoutRF error signal and optimise them.

d_doffloat, optional

A small offset applied to the DOFs to compute the gradients of the error signals

Examples

Take a typicaly Pound-Drever-Hall lock of a cavity. Here is some KatScript to setup such a model: >>> import finesse >>> from finesse.analysis.actions import OptimiseRFReadoutPhaseDC >>> >>> model = finesse.Model() >>> model.parse(‘’’ >>> l l1 >>> mod mod1 10M 0.1 mod_type=pm >>> readout_rf PD f=mod1.f phase=33 output_detectors=True optical_node=m1.p1.o >>> m m1 R=0.99 T=0.01 >>> m m2 R=1 T=0 >>> link(l1, mod1, m1, 1, m2) >>> lock cav_lock PD_I m2.phi 0.01 1e-3 >>> ‘’’)

We have defined a lock above using the I quadrature RF demodulation and feeding back to the m2 mirror position. We can optimise this demodulation phase by running. Here we manually provied which drives and readouts to use: >>> sol = model.run(OptimiseRFReadoutPhaseDC(“m2.phi”, ‘PD_I’)) >>> print(sol.phases) {‘PD’: 181.3535303754581} >>> print(model.PD.phase) 181.3535303754581

Alternatively, PD_Q could also be optimised for above. You can also just optimise all locks that are using RF readouts by providing no arguments: >>> sol = model.run(OptimiseRFReadoutPhaseDC()) >>> print(sol.phases) {‘PD’: 181.3535303754581}

To tell what was optimised, see the sol.phases dictionary.