Inhomogeneous mechanical losses in micro-oscillators with high reflectivity coating

Serra, Enrico; Cataliotti, F. S.; Marín, F.; Marino, Francesco; Pontin, A.; Prodi, G. A.; Bonaldi, M.

doi:10.1063/1.4728217

Cited by 13 publications

(13 citation statements)

References 62 publications

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“…From the comparison with the complete device, we can roughly [54] estimate as 5 × 10 −7 the loss contributed by the structural dissipation in the optical coating. This value is much lower than the typical loss angle in the coating, that is around 6 × 10 −4 [24,43], and confirms the efficiency of the low-deformation mirror design.…”

Section: B Mechanical-loss Measurementsupporting

confidence: 56%

“…Experimental parameters of a typical optomechanical device. Ω m is the angular frequency of the main mode and M its effective mass, estimated from thermal-noise measurements at room temperature [24]. The quality factor Q is measured from the decay of free oscillation.…”

Section: Discussionmentioning

confidence: 99%

“…The energy ratios for each modal shape can be easily evaluated by a finite-element (FE) study; therefore, the resulting total loss can be predicted from the loss angle of the coating and of the silicon substrate. Typical agreement of this procedure with experimental data is 20% [24]. Given the diameter of the mirror needed to obtain the required cavity finesse, the mechanical micro-oscillators are conceived to confine the high-reflectivity coating on a part moving as rigidly as possible.…”

Section: B Coating Mechanical-loss Controlmentioning

confidence: 96%

“…According to this relation, the loss due to the coating can be reduced if the associated strain energy is made negligible with respect to the total energy of the resonator. For this reason, in our resonators, the mirror is positioned on a part moving as rigidly as possible, to reduce the strain energy stored in the coating layer [24]. As shown in Fig.…”

Section: B Coating Mechanical-loss Controlmentioning

confidence: 99%

“…Actually, our previous generation devices allowed us to demonstrate useful physical effects, such as frequency-noise cancellation [21], parametric modulation and stabilization of the optical spring [22], and optimal filtering and detection [23]. However, in spite of the continuous progress [24,25], the system's quality factor is still far from optimal, and they showed residual coupling with the wafer modes, energy leakage through the supporting structure (clamping losses), and performance strongly affected by the supporting system. On the contrary, the device presented here solves all technical issues specifically related to the device.…”

Section: Introductionmentioning

confidence: 99%

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Low-Loss Optomechanical Oscillator for Quantum-Optics Experiments

et al. 2015

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We present an oscillating micromirror with mechanical quality factors Q up to 1.2 × 10 6 at cryogenic temperature and optical losses lower than 20 ppm. The device is specifically designed to ease the detection of ponderomotive squeezing (or, more generally, to produce a cavity quantum optomechanical system) at frequencies of about 100 kHz. The design allows one to keep under control both the structural loss in the optical coating and the mechanical energy leakage through the support. The comparison between devices with different shapes shows that the residual mechanical loss at 4.2 K is equally contributed by the intrinsic loss of the silicon substrate and of the coating, while at higher temperatures the dominant loss mechanism is thermoelasticity in the substrate. As the modal response of the device is tailored for its use in optical cavities, these features make the device very promising for quantum-optics experiments.

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Section: B Mechanical-loss Measurementsupporting

confidence: 56%

Section: Discussionmentioning

confidence: 99%

Section: B Coating Mechanical-loss Controlmentioning

confidence: 96%

Section: B Coating Mechanical-loss Controlmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Low-Loss Optomechanical Oscillator for Quantum-Optics Experiments

et al. 2015

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Dynamical back‐action effects in low loss optomechanical oscillators

et al. 2014

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The problem of the stability of a cavity optomechanical system based on an oscillator having at the same time low optical and mechanical losses is addressed. As it is the aim to extend the use of optical squeezing as a tool for improving quantum limited displacement sensing at low frequency, a family of opto-mechanical devices designed to work at frequencies of about 100 kHz was developed . The devices actually meet the initial design goals, but new requirements have emerged from the analysis of their behavior in optical cavities, due to the interaction between the cavity locking system and the low order normal modes of the devices.The optomechanics field of research has been gathering a lot of momentum during the last couple of years, driven by the achievement of long-awaited experimental results. For example, micro-and nano-oscillators can now be cooled down to an occupation number below unity, or very close to it, opening up the possibility to observe quantum phenomena [1][2][3][4][5][6].We are particularly interested in optical squeezing as a tool for improving quantum limited displacement sensing [7] in the audio-band, in particular for improving the sensitivity of gravitational wave interferometers [8]. Experiments have recently achieved squeezing around the mechanical resonance in the MHz range, using a silicon nanomechanical resonator [9], and a thin semi-transparent membrane within a Fabry-Pérot cavity [10]. At lower frequencies however, various sources of technical noise, such as thermal noise, phase/frequency noise associated with the input field and/or the slow cavity fluctuations, have detrimental effects on the manifestation of quantum phenomena, making lowfrequency ponderomotive squeezing much more difficult to achieve. As a first step, we are addressing these problems by developing a family of opto-mechanical devices specifically designed to ease the detection of pondero-motive squeezing (or, more generally, to produce a cavity quantum optomechanical system) at frequencies of about 100 kHz.Our approach is focused on relatively thick silicon oscillators with high reflectivity coating [11]. The relatively high mass (about 100 μg) of our devices is compensated by the capability to manage high power at low temperatures (down to 1 K), owing to a favorable geometric factor (thick connectors) and the excellent thermal conductivity of silicon crystals at cryogenic temperature. We point out that most of the schemes designed to detect quantum properties of light cannot take advantage from laser cooling of the mechanical oscillator involved in the measurement. Therefore, a low thermal noise background is required (i.e., low temperature), together with a weak interaction between the oscillator and its thermal bath (i.e., high mechanical quality factors Q).In such devices, the mirror coatings must provide high reflectivity and low losses, as radiation-pressure

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