Experimental demonstration of coupled optical springs

Abstract

Abstract. Optical rigidity will play an important role in improving the sensitivity of future generations of gravitational wave (GW) interferometers which employ high laser power in order to reach and exceed the standard quantum limit. Several experiments have demonstrated the combined effect of two optical springs on a single system for very low-weight mirror masses or membranes. In this paper we investigate the complex interactions between multiple optical springs and the surrounding apparatus in a system of comparable dynamics to a largescale GW detector. Using three 100 g mirrors to form a coupled cavity system capable of sustaining two or more optical springs, we demonstrate a number of different regimes of opto-mechanical rigidity and measurement techniques. Our measurements reveal couplings between each optical spring and the control loops that can affect both the achievable increase in sensitivity and the stability of the system. Hence this work establishes a better understanding of the realisation of the these techniques and paves the way to their application future GW observatories, such as upgrades to Advanced LIGO.

Radiation-Pressure-Mediated Control of an Optomechanical Cavity

“…Braginsky et al [3], Buonanno and Chen [4], and Harms et al [5] proposed using the optical bar and optical spring to enhance the sensitivity of gravitational wave detectors. Over the past two decades, many experiments have observed the optical spring in a variety of systems [1,[6][7][8][9][10][11][12][13][14][15] and used it to optically cool mechanical resonators [16][17][18][19][20][21][22][23][24]. Furthermore, proposals to increase the sensitivity of Michelson-type gravitational wave detectors using the optical spring effect have included adding a signal-recycling cavity [25][26][27], using a detuned cavity to amplify the interferometric signal [28], adding a signal-extraction cavity or resonant sideband extraction [29,30], and dynamically tuning the cavities to follow a gravitational wave chirp signal [31,32].…”

Radiation-pressure-mediated control of an optomechanical cavity

“…Braginsky et al [4], Buonanno and Chen [5], and Harms et al [6] proposed using the optical bar and optical spring to enhance the sensitivity of gravitational wave detectors. Over the past two decades, many experiments have observed the optical spring in a variety of systems [1,[7][8][9][10][11][12][13][14][15][16] and used it to optically cool mechanical resonators [17][18][19][20][21][22][23][24][25]. Furthermore, proposals to increase the sensitivity of Michelsontype gravitational wave detectors using the optical spring effect have included adding a signal-recycling cavity [26][27][28], using a detuned cavity to amplify the interferometric signal [29], adding a signal-extraction cavity or resonant sideband extraction [30,31], and dynamically tuning the cavities to follow a gravitational wave chirp signal * tcorbitt@phys.lsu.edu [32,33].…”

Engineering the optical spring via intra-cavity optical-parametric amplification

“…To further exploit the optical spring, it was proposed to dynamically change the detuning by moving the SR/SE mirror in order to follow expected chirps of GW signals [14,15]. The optical spring was observed in several experiments [12,[16][17][18][19][20][21][22][23][24][25][26]. The gravitational-wave detectors GEO 600 [27], Advanced LIGO [28], Advanced Virgo [29], and KA-GRA [30] do use either SR or SE cavities, but so far have not yet employed the optical spring for a sensitivity enhancement due to the requirement of additional control techniques.…”