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CITF simulations
Test of the central part of the interferometer (PR+BS+IMs).
The central interferometer will be the first part to be commissioned, so we better cross-check our simulation results before the installation. The simulation packages will also later be used to ease the commissioning and help to understand the working of the interferometer.
Results:
To compare simulation results, we main look at 3 quantities:- The carrier gain in the PRC: given by the carrier circulating power divided by the input carrier power
- The sidebands gain
- The carrier power at the dark port normalized for 1W of input carrier light
The perfect case:
| Packages | DarkF | FOG | OSCAR |
| Carrier gain PRC | 47.8 | 47.8 | |
| SB gain | 42.6 | 42.6 | |
| DP power | 2.4e-6 | 4E-6 |
Example of common path error:
Perfect case but with RoC PRM of 1420m instead of 1430m
| Packages | DarkF | FOG | OSCAR |
| Carrier gain PRC | 36.2 | 36.4 | |
| SB gain | 33.1 | 33.1 | |
| DP power | 1.2e-6 | 1.4E-6 |
Example of differential path error:
Perfect case but with NI RoC HR of 1430 instead of 1420m
| Packages | DarkF | FOG | OSCAR |
| Carrier gain PRC | 43 | 39.8 | |
| SB gain | 39.3 | 36.0 | |
| DP power | 4.e-3 | 7E-3 |
Configuration:
Number of points of the grid: 256 X 256
Size of the grid: 0.4 X 0.4 m
Diameter of the mirror: 0.33 m
RoC IM HR: 1420 m, RoC IM AR: 1420 m (equivalent to a meniscus lens)
Length IM substrate: 20 cm, refractive index 1.45
Transmission ITM: 0.014
RoC PR: 1430 m
BS perfect, transmission: 0.05
Input beam is matched to the PRC cavity
Some distances (very close to the real one, include thickness of POP/CP/BS):
PR - BS: 5.925 m
BS - NIM: 5.726 m
BS - WIM: 5.496 m
Modulation SB: 12.778 MHz, to be adjusted to be resonant in the CITF.
OSCAR file to do the simulations is here: OSCAR CITF
(DarkF Modulation SB: 12.994 MHz)