A silicon Brillouin laser

Otterstrom, Nils T.; Behunin, Ryan O.; Kittlaus, Eric A.; Wang, Zheng; Rakich, Peter T.

doi:10.1126/science.aar6113

Cited by 240 publications

(150 citation statements)

References 40 publications

(36 reference statements)

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“…1), but it also increases the scattering loss into the bulk. For many applications [10,11,19], the quality factor divided by mode area Q/Aeff is an important figure of merit; it characterizes the buildup factor of the acoustic field in the cavity. The chosen etch depth of 115 nm (2.8% λ) is a good trade-off between a small mode area and a high Q factor [8,9].…”

Section: Phononic Band Structure Engineeringmentioning

confidence: 99%

Phononic Band Structure Engineering for High- Q Gigahertz Surface Acoustic Wave Resonators on Lithium Niobate

et al. 2019

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Phonons at gigahertz frequencies interact with electrons, photons, and atomic systems in solids, and therefore have extensive applications in signal processing, sensing, and quantum technologies. Surface acoustic wave (SAW) resonators that confine surface phonons can play a crucial role in such integrated phononic systems due to small mode size, low dissipation, and efficient electrical transduction. To date, it has been challenging to achieve high quality (Q) factor and small phonon mode size for SAW resonators at gigahertz frequencies. Here, we present a methodology to design compact high-Q SAW resonators on lithium niobate operating at gigahertz frequencies. We experimentally verify out designs and demonstrate Q factors in excess of 2×10 4 at room temperature (6×10 4 at 4 Kelvin) and mode area as low as 1.87 λ 2 . This is achieved by phononic band structure engineering, which provides high confinement with low mechanical loss. The frequency-Q products (fQ) of our SAW resonators are greater than 10 13 . These high-fQ and small mode size SAW resonators could enable applications in quantum phononics and integrated hybrid systems with phonons, photons, and solid-state qubits.

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Section: Phononic Band Structure Engineeringmentioning

confidence: 99%

Phononic Band Structure Engineering for High- Q Gigahertz Surface Acoustic Wave Resonators on Lithium Niobate

et al. 2019

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“…More recently, the SBS process has attracted considerable interest in microscale and nanoscale devices [12]. Brillouin laser action has been demonstrated in several microcavity resonator systems including silica [13][14][15][16], CaF 2 [17], and silicon [18], and Brillouin amplification has been demonstrated in integrated chalcogenide waveguides [19]. In silicon waveguides, the use of confinement to enhance amplification has been studied [20].…”

mentioning

confidence: 99%

“…In this regime, the system would enter a cavity optomechanical regime [25,28,29] wherein optical damping can exceed mechanical damping. This would require a modification to the SBL linewidth formula [18].…”

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confidence: 99%

Phonon-Limited-Linewidth of Brillouin Lasers at Cryogenic Temperatures

2017

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Laser linewidth is of central importance in spectroscopy, frequency metrology, and all applications of lasers requiring high coherence. It is also of fundamental importance, because the Schawlow-Townes laser linewidth limit is of quantum origin. Recently, a theory of stimulated Brillouin laser (SBL) linewidth has been reported. While the SBL linewidth formula exhibits power and optical Q factor dependences that are identical to the Schawlow-Townes formula, a source of noise not present in conventional lasers, phonon occupancy of the Brillouin mechanical mode is predicted to be the dominant SBL linewidth contribution. Moreover, the quantum limit of the SBL linewidth is predicted to be twice the Schawlow-Townes limit on account of phonon participation. To help confirm this theory the SBL fundamental linewidth is measured at cryogenic temperatures in a silica microresonator. Its temperature dependence and the SBL linewidth theory are combined to predict the number of thermomechanical quanta at three temperatures. The result agrees with the Bose-Einstein phonon occupancy of the microwave-rate Brillouin mode in support of the SBL linewidth theory prediction. DOI: 10.1103/PhysRevLett.119.143901 Stimulated Brillouin scattering (SBS) is a third-order (χ 3 ) optical nonlinearity that results from the interaction between photons and acoustic phonons in a medium [1][2][3][4]. SBS has practical importance in optical fiber systems [5,6] where it is an important signal impairment mechanism in long-distance transmission systems [7] and makes possible all-fiber lasers [8] as well as tunable, slow-light generation [9]. Power fluctuation resulting from thermal phonons has also been studied in fiber-optic SBS Stokes wave generation [10], and the intensity and phase noise have been measured in narrow-linewidth Brillouin lasers [11]. More recently, the SBS process has attracted considerable interest in microscale and nanoscale devices [12]. Brillouin laser action has been demonstrated in several microcavity resonator systems including silica [13][14][15][16], CaF 2 [17], and silicon [18], and Brillouin amplification has been demonstrated in integrated chalcogenide waveguides [19]. In silicon waveguides, the use of confinement to enhance amplification has been studied [20]. SBS is also a powerful tool for integrated photonics signal processing [21][22][23], and it has been applied to realize a chip-based optical gyroscope [24]. Moreover, at radio-frequency rates, the SBS damping rate is low enough in certain systems to enable cavity optomechanical effects [25] including optomechanical cooling [26] and optomechanical-induced transparency [27].This work studies a recent prediction concerning the fundamental linewidth (i.e., nontechnical noise contribution to linewidth) of the stimulated Brillouin laser (SBL). The analysis of fundamental fluctuations in Brillouin devices falls into a more general category of optomechanical oscillators in which phonons participate in the oscillation process [28,29]. This participation creates a channe...

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“…Starting with equation (1), we consider two optical tones in waveguides A and B by keeping only n={−1, 0}, leaving us with We note that in this inter-modal process, the phonons do not have a vanishing group velocity as in the FSBS case. However, the axial spatial evolution of the acoustic field is very slow compared to the optical fields and can be adiabatically eliminated, such that equation (E2) is still valid [21,41]. The number of photons in each waveguide is conserved, which can be seen from the derivatives…”

Section: Appendix E Limited Optical Cascadingmentioning

confidence: 99%

Shaping nonlinear optical response using nonlocal forward Brillouin interactions

et al. 2020

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In most practical scenarios, optical susceptibilities can be treated as a local property of a medium. For example, in the context of nonlinear optics we can typically treat the Kerr and Raman response as local, such that optical fields at one location do not produce a nonlinear response at distinct locations in space. This is because the electronic and vibrational disturbances produced within the material are confined to a region that is smaller than an optical wavelength. By comparison, Brillouin interactions, mediated by traveling-wave acoustic phonons, can result in a highly nonlocal nonlinear response as the elastic waves generated in the process can occupy a region in space much larger than an optical wavelength. The unique properties of these interactions can be exploited to engineer new types of processes, where highly delocalized phonon modes serve as an engineerable channel that mediates scattering processes between light waves propagating in distinct optical waveguides. These types of nonlocal optomechanical responses have recently been demonstrated as the basis for information transduction, however the nontrivial dynamics of such systems has yet to be explored. In this work, we show that the third-order nonlinear process resulting from spatially extended Brillouin-active phonon modes involves mixing products from spatially separated, optically decoupled waveguides, yielding a nonlocal susceptibility. Building on these concepts, we illustrate how nontrivial multi-mode acoustic interference can produce a nonlocal susceptibility with a multi-pole frequency response, as the basis for new optical and microwave signal processing schemes within traveling wave systems.

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A silicon Brillouin laser

Cited by 240 publications

References 40 publications

Phononic Band Structure Engineering for High- Q Gigahertz Surface Acoustic Wave Resonators on Lithium Niobate

Phononic Band Structure Engineering for High- Q Gigahertz Surface Acoustic Wave Resonators on Lithium Niobate

Phonon-Limited-Linewidth of Brillouin Lasers at Cryogenic Temperatures

Shaping nonlinear optical response using nonlocal forward Brillouin interactions

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