Giant gain enhancement in surface‐confined resonant Stimulated Brillouin Scattering

Dostart, Nathan; Kim, Seunghwi; Bahl, Gaurav

doi:10.1002/lpor.201500141

Cited by 21 publications

(19 citation statements)

References 65 publications

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“…From equation (16) we see that regardless of the detail of initial acoustic spectrum, the effect of the noise always bring the acoustic spectrum back to the value n v b b ,0…”

Section: High Group Velocity Acoustic Modes At Thermal Equilibriummentioning

confidence: 99%

Brillouin cooling in a linear waveguide

2016

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Brillouin scattering is not usually considered as a mechanism that can cause cooling of a material due to the thermodynamic dominance of Stokes scattering in most practical systems. However, it has been shown in experiments on resonators that net phonon annihilation through anti-Stokes Brillouin scattering can be enabled by means of a suitable set of optical and acoustic states. The cooling of traveling phonons in a linear waveguide, on the other hand, could lead to the exciting future prospect of manipulating unidirectional phonon fluxes and even the nonreciprocal transport of quantum information via phonons. In this work, we present an analysis of the conditions under which Brillouin cooling of phonons of both low and high group velocities may be achieved in a linear waveguide. We analyze the three-wave mixing interaction between the optical and traveling acoustic modes that participate in forward Brillouin scattering, and reveal the key regimes of operation for the process. Our calculations indicate that measurable cooling may occur in a system having phonons with spatial loss rate that is of the same order as the spatial optical loss rate. If the Brillouin gain in such a waveguide reaches the order of 10 5 m −1 W −1 , appreciable cooling of phonon modes may be observed with modest pump power of a few mW.

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“…From equation (16) we see that regardless of the detail of initial acoustic spectrum, the effect of the noise always bring the acoustic spectrum back to the value n v b b ,0…”

Section: High Group Velocity Acoustic Modes At Thermal Equilibriummentioning

confidence: 99%

Brillouin cooling in a linear waveguide

2016

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“…While these first experimental systems utilized the intrinsic photoelastic response of the waveguide core to produce strong Brillouin coupling 42 , it was also discovered that new mechanisms for Brillouin coupling emerge when light is confined below the optical wavelength-scale 21,34,44,45 . Such interactions, which result from the strong interaction of light with waveguide boundaries, become particularly important within high-index contrast waveguides having small cross-sections.…”

Section: Brillouin-active Waveguidesmentioning

confidence: 99%

Brillouin integrated photonics

et al. 2019

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A recent renaissance in Brillouin scattering research has been driven by the increasing maturity of photonic integration platforms and nanophotonics. The result is a new breed of chip-based devices that exploit acousto-optic interactions to create lasers, amplifiers, filters, delay lines and isolators. Here we provide a detailed overview of Brillouin scattering in integrated waveguides and resonators, covering key concepts such as the stimulation of the Brillouin process, in which the optical field itself induces acoustic vibrations, the importance of acoustic confinement, methods for calculating and measuring Brillouin gain, and the diversity of materials platforms and geometries. Our review emphasizes emerging applications in microwave photonics, signal processing and sensing, and concludes with a perspective for future directions.

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“…Indirect intermodal scattering [22] can be enabled between the optical modes as a result of the photoelastic perturbations of the medium by the driven acoustic wave (Ω, q) [20,21]. While this optically resonant structure sacrifices the bandwidth over which acousto-optical interactions can occur, it provides giant opto-acoustic gain that is necessary to obtain appreciable light-vibration coupling within a small form factor [26]. The requisite phase matching conditions are illustrated in ω −k space in Fig.…”

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Time-reversal symmetry breaking with acoustic pumping of nanophotonic circuits

Sohn¹,

Kim²,

Bahl³

2018

Nature Photon

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Achieving non-reciprocal light propagation via stimuli that break time-reversal symmetry, without magneto-optics, remains a major challenge for integrated nanophotonic devices. Recently, optomechanical microsystems in which light and vibrational modes are coupled through ponderomotive forces, have demonstrated strong non-reciprocal effects through a variety of techniques, but always using optical pumping. None of these approaches have demonstrated bandwidth exceeding that of the mechanical system, and all of them require optical power, which are both fundamental and practical issues. Here we resolve both of these challenges through breaking of time-reversal symmetry using an acoustic pump in an integrated nanophotonic circuit. GHz-bandwidth optomechanical non-reciprocity is demonstrated using the action of a 2-dimensional surface acoustic wave pump, that simultaneously provides non-zero overlap integral for light-sound interaction and also satisfies the necessary phase-matching. We use this technique to produce a simple frequency shifting isolator (i.e. a non-reciprocal modulator) by means of indirect interband scattering. We demonstrate mode conversion asymmetry up to 15 dB, efficiency as high as 17%, over bandwidth exceeding 1 GHz.Non-reciprocal devices, in which time reversal symmetry is broken for light propagation, provide critical functionalities for signal routing and source protection in photonic systems. The most commonly encountered nonreciprocal devices are isolators and circulators, which can be implemented using a variety of techniques encompassing magneto-optics [1, 2], parity-time symmetry breaking [3], spin-polarized atom-photon interactions [4,5], and optomechanical interactions [6][7][8][9][10][11][12]. On the other hand, recent developments 1 arXiv:1707.04276v2 [physics.optics] 25 Jul 2017 reveal a much broader and compelling vision of using time-reversal symmetry breaking for imparting protection against defects, through analogues of the quantum Hall effect [13] in both topological [14][15][16] and non-topological systems [17].The use of optomechanical coupling [18] for breaking time-reversal symmetry via momentum biasing [12,19] and synthetic magnetism [10,11] is particularly attractive since strong dispersive features can be readily produced, without needing materials with gain or magneto-optical activity. Additionally, the potential for complete isolation with ultralow loss [7] is a significant advantage over state-of-the-art in chip scale magneto-optics. All these systems feature dynamic reconfigurability through the pump laser fields and can potentially be implemented in foundries with minimal process modification. Unfortunately, all realizations of optomechanical nonreciprocal interactions to date only operate over kHz-MHz bandwidth. This fundamental constraint arises simply because the interaction is determined by the mechanical linewidth, which is traditionally 6-9 orders of magnitude lower than the optical system (potentially several THz). In this work we present a new appro...

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Giant gain enhancement in surface‐confined resonant Stimulated Brillouin Scattering

Cited by 21 publications

References 65 publications

Brillouin cooling in a linear waveguide

Brillouin cooling in a linear waveguide

Brillouin integrated photonics

Time-reversal symmetry breaking with acoustic pumping of nanophotonic circuits

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