This is a simple snippet of code showing how to change the Schnupp asymmetry in the finesse3 virgo model.

The process is quite straightforward and is based on simply changing the length of the space between the beamsplitter and one of the compensation plates.

An important step to follow the Schnupp asymmetry change is to readjust the length of the PR and SR cavities in order to keep the correct FSR and to maintain the sidebands resonance conditions.

virgo = finesse.virgo.Virgo() # creating a virgo model using the custom Virgo kat file


print(virgo.model.lSchnupp.value.eval()) # print the initial values
print(virgo.model.lBS_CPN.L.value)
print(virgo.model.lBS_CPW.L.value)
virgo.model.lBS_CPW.L.value += -1 #add one meter to one of the small arms
virgo.adjust_PRC_length() # readjust the PRC length (this adjusts the distance between PR and BS)
virgo.adjust_SRC_length() # same for SRC
print(virgo.model.lSchnupp.value.eval()) # print the values after the changes 
print(virgo.model.lBS_CPN.L.value)
print(virgo.model.lBS_CPW.L.value)