Stimulated Brillouin scattering materials, experimental design and applications: A review

Quantum acousto-optic control of light-matter interactions in nanophotonic networks

“…3(c). This approximate theory is compared with an exact simulation of the emission process based on the full Hamiltonian (2). We see that within the regime of validity, g 0 ≪ Ω r , the system dynamics is captured very well by the Markovian model.…”

“…5(b) we show how this acoustic conveyor belt can be used for implementing a state transfer protocol between two emitters with x 2 > x 1 . In this example, the first emitter is initially prepared in the excited state e⟩ and we are interested in the excitation probability of the second emitter, p (2) e (T f ), at a final time T f , once the acoustic wave has left the interaction region. The frequencies of both emitters are set to ω eg ≃ ω c −0.096Ω r , which matches the frequency of the lowest photon bound state for a value of V a E r = 0.5.…”

“…This property can be attributed to the vast difference in frequency and propagation speed, which makes a direct coupling of photons and phonons very inefficient. Nevertheless, residual Brillouin scattering [1,2], where photons are scattered into other orthogonal modes by simultaneously emitting or absorbing phonons, still constitutes a major limitation for optical communication [3,4], in particular when operating at higher power. In addition, has been suggested of using intense acoustic waves for the control of weak optical fields, for example, for frequency conversion [5,6], on-chip phase modulation [7], or nonreciprocal scattering of optical beams [8,9].…”

Stimulated Brillouin Review: Invented 50 Years Ago and Applied Today

“…Given that the input is just a few acoustic phonons, the factor of 21 is traditionally required to provide enough gain for an easily measurable signal. This critical power is given by [5] (0) = 21…”

“…This simple equation consists of geometrical factors and lumps everything else into a peak gain coefficient. The peak gain coefficient g o , shown below, [5] contains all the physical parameters of the Brillouin material, with e as the electrostriction coefficient, which serves as the source of the nonlinearity. Here n is refractive index, v ac is the velocity of acoustic phonons, is the average medium density, and Γ B is the Brillouin linewidth angular frequency.…”