Mode profiles and Airy distributions of Fabry-Pérot resonators with frequency-dependent mirror reflectivity

2017 ◽  
Author(s):  
Nur Ismail ◽  
Cristine Calil Kores ◽  
Dimitri Geskus ◽  
Markus Pollnau
Galaxies ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 80
Author(s):  
Jonathan Brooks ◽  
Maddalena Mantovani ◽  
Annalisa Allocca ◽  
Julia Casanueva Diaz ◽  
Vincenzo Dattilo ◽  
...  

The sensitivity of interferometric gravitational wave detectors is optimized, in part, by balanced finesse in the long Fabry–Perot arm cavities. The input test mass mirrors of Advanced Virgo feature parallel faces, which creates an etalon within the substrate, adding variability in the total mirror reflectivity, in order to correct imbalanced finesse due to manufacturing tolerances. Temperature variations in mirror substrate change the optical path length primarily through varying the index of refraction and are tuned to correct for a finesse imbalance of up to 2.8% by a full etalon fringe of 0.257 K. A negative feedback control system was designed to control the mirror temperature by using an electrical resistive heating belt actuator for a heat transfer process modeled as a two-pole plant. A zero controller filter was designed which achieves temperature control within 2.3% of the etalon fringe and recovers to within 10% of the working point within 32 hours after a step input of one etalon fringe. A preliminary unlock condition control designed to compensate when the interferometer unlocks shows that the control remains stable even after a drastic change in the plant due to the absence of the laser heating. Further improvements to the control must also consider the full heat transfer mechanisms by using modern control state space models.


2020 ◽  
pp. 1027-1031
Author(s):  
Ali Hassan Khidhir

In this work, the external switching dynamics of a Fabry-Perot etalon are studied via optical bistability system simulation. The simulated set-up of this investigation consists of two laser beams; the first beam is continuous (CW) which is considered as a biasing beam and capable of holding the bistable system for a certain range, which we are interested in, from a point that is very close self-switching to a point where the switching is unachievable. The second beam is modulated by passing the first beam through an acousto-optic modulator (AOM) to produce pulses with a minimum rise time and is used as an external source (coherent switching). In this work, we obtained the optical bistable loops by applying absorption coefficient (α) = 20cm-1, e sample etalon thickness (D) = 110μm, forward mirror reflectivity (Rf) = 0.6, and backward mirror reflectivity (Rb) = 0.95. The steady state characteristic of an initial detuning of the cavity (φ0) = 0.8 was studied at the conditions of no external input pulse intensity (M(t) = 0) and switching that takes place at Is(ON)= 0.57mW and Is(OFF) = 0.4mW.


2012 ◽  
Vol 86 (5) ◽  
Author(s):  
H. Y. Yao ◽  
N. C. Chen ◽  
T. H. Chang ◽  
H. G. Winful

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