Noise and dynamics in forward Brillouin interactions

Kharel, Prashanta; Behunin, Ryan O.; Renninger, William H.; Rakich, Peter T.

doi:10.1103/physreva.93.063806

Cited by 43 publications

(107 citation statements)

References 71 publications

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“…A related feature of this is that (in the absence of optical loss and dispersion) the acoustic amplitude is constant along the waveguide: the sound wave is not amplified. This is in agreement with an earlier work on the optical single-pass gain of FBS structures [18]. As a result, the effect of cascaded FBS in the non-dispersive regime cannot be observed in the RF-domain by detecting the interference within the optical output with a photodetector.…”

Section: Example: Two-tone Excitation and Zero Optical Losssupporting

confidence: 93%

“…A key finding is that without dispersion the optically driven vibrations only cause an additional optical phase modulation. This is in agreement with the recent theoretical observation that FBS in the absence of dispersion has negative single-pass gain [18]. We then show that weak dispersion leads to two different regimes: in one regime dispersion washes out intensity fluctuations of an incident pump laser while generating additional phase noise.…”

Section: Introductionsupporting

confidence: 92%

“…Although observed experimentally as early as 1985 [5] in conventional step index fibers, FBS appears most naturally in waveguides that possess complex transverse structure; FBS has been observed in photonic crystal fibers (PCFs) and tapers [6][7][8][9][10][11][12], while the parallel development of on-chip integrated optical circuits has led to experimental observation of FBS in semiconductor nanowires [13,14], and theoretical consideration of slot waveguides [15] and hybrid photonic-phononic waveguides [16]. The observation that FBS is much easier to generate in integrated silicon circuits than its backward counterpart [14,17,18] means that FBS is critically important for applications that seek to harness the interaction of sound and light on the nanoscale.…”

Section: Introductionmentioning

confidence: 99%

“…The established theory for Brillouin processes, in which a single pair of optical fields are related by an acoustic mode, has been developed from the study of backward SBS [2,19,20], backward GAWBS [21] and cladding BS [22] in homogeneous materials and optical fibers. With some important modifications [18,23,24], for backward SBS this formalism can be directly applied to the nanostructures that are of recent interest. However the existing theory is not well-suited to the study of FBS.…”

Section: Introductionmentioning

confidence: 99%

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Cascaded forward Brillouin scattering to all Stokes orders

et al. 2017

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View the article online for updates and enhancements. AbstractInelastic scattering processes such as Brillouin scattering can often function in cascaded regimes and this is likely to occur in certain integrated opto-acoustic devices. We develop a Hamiltonian formalism for cascaded Brillouin scattering valid for both quantum and classical regimes. By regarding Brillouin scattering as the interaction of a single acoustic envelope and a single optical envelope that covers all Stokes and anti-Stokes orders, we obtain a compact model that is well suited for numerical implementation, extension to include other optical nonlinearities or short pulses, and application in the quantum-optics domain. We then theoretically analyze intra-mode forward Brillouin scattering (FBS) for arbitrary waveguides with and without optical dispersion. In the absence of optical dispersion, we find an exact analytical solution. With a perturbative approach, we furthermore solve the case of weak optical dispersion. Our work leads to several key results on intra-mode FBS. For negligible dispersion, we show that cascaded intra-mode FBS results in a pure phase modulation and discuss how this necessitates specific experimental methods for the observation of fiber-based and integrated FBS. Further, we discuss how the descriptions that have been established in these two classes of waveguides connect to each other and to the broader context of cavity opto-mechanics and Raman scattering. Finally, we draw an unexpected striking similarity between FBS and discrete diffraction phenomena in waveguide arrays, which makes FBS an interesting candidate for future research in quantum-optics.

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Section: Example: Two-tone Excitation and Zero Optical Losssupporting

confidence: 93%

Section: Introductionsupporting

confidence: 92%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Cascaded forward Brillouin scattering to all Stokes orders

et al. 2017

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“…The stimulated Brillouin coefficient can be used to estimate spontaneous forward Brillouin scattering, a similar process in which a single pump tone scatters from thermally excited and phase-matched phonons [33]. The total spontaneously generated optical power produced by the Brillouin active phonon mode is given by…”

Section: Spontaneous Scattering and Noisementioning

confidence: 99%

Guided-wave Brillouin scattering in air

Renninger

Behunin

Rakich

2016

Optica

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Here we identify a new form of optomechanical coupling in gas-filled hollow-core fibers. Stimulated forward Brillouin scattering is observed in air in the core of a photonic bandgap fiber. A single resonance is observed at 35 MHz, which corresponds to the first excited axial-radial acoustic mode in the air-filled core. The linewidth and coupling strengths are determined by the acoustic loss and electrostrictive coupling in air, respectively. A simple analytical model, refined by numerical simulations, is developed that accurately predicts the Brillouin coupling strength and frequency from the gas and fiber parameters. Since this form of Brillouin coupling depends strongly on both the acoustic and dispersive optical properties of the gas within the fiber, this new type of optomechanical interaction is highly tailorable. These results allow for forward Brillouin spectroscopy in dilute gases, could be useful for sensing and will present a power and noise limitation for certain applications.Hollow-core photonic bandgap fibers (HC-PBF) are unique for their ability to guide light in air through Bragg reflection from a periodic silica matrix that forms the waveguide cladding [1][2][3] (Fig. 1(a)). In comparison to conventional silica (step-index) fibers, Bragg guidance in HC-PBF drastically reduces the nonlinear interactions with silica and increases the power handling to permit new forms of high power laser delivery [4], pulse compression [5], and light sources [6]. Conversely, the introduction of atomic vapors within these hollow-core fibers produces sustained photon-atom interactions over unprecedented length scales, which enables new light sources for both classical [7] and quantum [8][9][10][11][12] applications. While electronic nonlinearities are widely studied in such fibers [1][2][3], comparatively little is known of their acousto-optic (or optomechanical) interactions, and the dynamics, and noise that they can produce. Only recently has coupling between MHz elastic waves within the silica matrix been quantified [13], and identified as a source of noise in quantum optics [13,14].In this paper, we show that photon-phonon coupling mediated by air (gasses) within the hollow core of the fiber constitutes a much larger and perhaps more tailorable form of optomechanical coupling. Through a combination of theory and experiment, we show that the hollow core of the fiber acts as a conduit for guided acoustic waves in air. Optical waves that are guided in this same region produce strong photo-acoustic coupling to these sound waves, yielding appreciable forwardBrillouin coupling at MHz frequencies. Using precision spectroscopy methods, we identify a single air-mediated Brillouin resonance at 35 MHz with 20 times stronger photo-acoustic coupling than is produced by elastic waves in the silica cladding alone. We show that the strength, frequency, and character of this Brillouin resonance is explained by the properties of the gas filling the core and the dimension of the hollow-core fiber. Since this form of Brillouin coupl...

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