Enhancement of mechanical Q for low phase noise optomechanical oscillators

Rocheleau, Tristan O.; Grine, Alejandro J.; Grutter, Karen E.; Schneider, Robert A.; Quack, Niels; Wu, Ming C.; Nguyen, C.T.-C.

doi:10.1109/memsys.2013.6474191

Cited by 11 publications

(9 citation statements)

References 12 publications

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“…The optical resonance shape is Lorentzian (see Figure 3 (b)), and therefore the modulation is non-linear. This results in generation of multiple harmonics of the fundamental oscillation frequency, as observed earlier in opto-mechanical oscillators which function based on the same modulation scheme [19], [20]. Figure 7 (a) shows measured harmonics all the way up to 16.4GHz.…”

Section: Opto-acoustic Oscillator (Oao)supporting

confidence: 62%

Partial Gap Transduced MEMS Optoacoustic Oscillator Beyond Gigahertz

Tallur

Bhave

2015

J. Microelectromech. Syst.

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Electrostatically actuated microelectromechanical system (MEMS) oscillators are limited to few megahertzgigahertz range on account of transduction inefficiency at higher frequencies. Piezoelectric transduction affords lower motional impedances at high frequencies, however mass-loading on account of metal electrodes imposes practical limits on the mechanical quality factor of piezoelectric resonators in the gigahertz frequency regime. In this paper, we present a silicon optoacoustic oscillator operating at 2.05 GHz with signal power 18 dBm and phase noise −80 dBc/Hz at 10-kHz offset from carrier. We employ displacement amplification and partial air gap capacitive transduction to enhance the transduction efficiency. An unconventional photolithography step is performed on a released MEMS structure, which greatly simplifies the fabrication process and allows electrical contact with the electrodes. Builtin nonlinear optomechanical modulation provides noiseless upconversion of the oscillation signal all the way up to 16.4 GHz with −45-dBm signal power. We develop a phase noise model for the oscillator and identify the photodetector shot noise to be the dominant noise source. Using a high gain and low noise avalanche photodetector enables reduction of the far-from-carrier phase noise floor by 15dB. The phase noise model provides insights into understanding the influence of laser detuning on the oscillator noise performance, which has not been studied to date.[ 2013-0291]Index Terms-Opto-acoustic oscillator, phase noise, displacement amplifier, atomic layer deposition (ALD).

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Section: Opto-acoustic Oscillator (Oao)supporting

confidence: 62%

Partial Gap Transduced MEMS Optoacoustic Oscillator Beyond Gigahertz

Tallur

Bhave

2015

J. Microelectromech. Syst.

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“…6d). These arise from nonlinear modulation of the optical field due to the Lorentzian optical mode shape, as reported in other systems [33][34][35].…”

Section: Flexible Mechanical Resonator Designmentioning

confidence: 57%

Slot-mode optomechanical crystals: a versatile platform for multimode optomechanics

Grutter¹,

Davanço²,

Srinivasan³

2015

Optica

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Cavity optomechanical systems are being studied for their potential in areas such as metrology, communications, and quantum information science. For a number of recently proposed applications in which multiple optical and mechanical modes interact, an outstanding challenge is to develop multimode architectures that allow flexibility in the optical and mechanical sub-system designs while maintaining the strong interactions that have been demonstrated in single-mode systems. To that end, we demonstrate slot-mode optomechanical crystals, devices in which photonic and phononic crystal nanobeams separated by a narrow slot are coupled via optomechanical interactions. These nanobeam pairs are patterned to confine a mechanical breathing mode at the center of one beam and a low-loss optical mode in the slot between the beams. This architecture affords great design flexibility towards multimode optomechanics, as well as substantial optomechanical coupling rates. We show this by producing slot-mode devices in stoichiometric Si3N4, with optical modes in the 980 nm band coupled to mechanical modes at 3.4 GHz, 1.8 GHz, and 400 MHz. We exploit the Si3N4 tensile stress to achieve slot widths down to 24 nm, which leads to enhanced optomechanical coupling, sufficient for the observation of optomechanical self-oscillations at all studied frequencies. We then develop multimode optomechanical systems with triple-beam geometries, in which two optical modes couple to a single mechanical mode, and two mechanical modes couple to a single optical mode. Taken together, these results demonstrate great flexibility in the design of multimode chip-scale optomechanical systems with large optomechanical coupling.

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“…Such optomechanical oscillations were first demonstrated by Vahala group using micro-toroid structures [10][11][12], which then stimulated a series of research works realizing optomechanical oscillations using differ-ent device designs and materials, such as flexural beams [13,14], micro-disk resonators [15,16], micro-wheel resonators [17][18][19][20], micro-spheres [21], capillaries [22], photonic crystals [23]. Technical aspects of these oscillations such as injection-locking [24,25], photonic/RF downconversion [26,27], synchronization [28,29] and mass sensing applications [30] have also been explored.…”

Section: Introductionmentioning

confidence: 99%

Phase noise of self-sustained optomechanical oscillators

2014

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In this paper we present a theory that predicts the phase noise characteristics of self-sustained optomechanical oscillators. By treating the cavity optomechanical system as a feedback loop consisting of an optical cavity and a mechanical resonator, we analytically derive the transfer functions relating the amplitude/phase noise of all the relevant dynamical quantities from the quantum Langevin equations, and obtain a closed-form expressions for the phase noise spectral densities contributed from thermomechanical noise, photon shot noise, and low-frequency technical laser noise. We numerically calculate the phase noise for various situations and perform a sample calculation for an experimentally demonstrated system. We also show that the presented model reduces to the well-known Leeson's phase noise model when the amplitude noise and the amplitude/phase noise inter-transfers are ignored

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Enhancement of mechanical Q for low phase noise optomechanical oscillators

Cited by 11 publications

References 12 publications

Partial Gap Transduced MEMS Optoacoustic Oscillator Beyond Gigahertz

Partial Gap Transduced MEMS Optoacoustic Oscillator Beyond Gigahertz

Slot-mode optomechanical crystals: a versatile platform for multimode optomechanics

Phase noise of self-sustained optomechanical oscillators

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