Forward Brillouin scattering in hollow-core photonic bandgap fibers

We quantify the strength of stimulated forward Brillouin scattering in hollow-core photonic bandgap fiber through a combination of experiments and multi-physics simulations. Brillouin spectroscopy methods reveal a family of densely spaced Brillouin-active phonon modes below 100 MHz with coupling strengths that approach those of conventional silica fiber. The experimental results are corroborated by multi-physics simulations, revealing that relatively strong optomechanical coupling is mediated by a combination of electrostriction and radiation pressure within the nano-scale silica-air matrix; the nontrivial mechanical properties of this silica-air matrix facilitate the large optomechanical response produced by this system. Simulations also reveal an incredible sensitivity of the Brillouin spectrum to fiber critical dimensions, suggesting opportunity for enhancement or suppression of these interactions. Finally, we relate the measured and calculated couplings to the noise properties of the fiber as the foundation for phase-and polarization-noise estimates in hollow-core fiber. More generally, such Brillouin interactions are an important consideration in both the high and low optical intensity limits.open11115sciescopu

Nonlinear optics: Nonlinear virtues of multimode fibre

Supercontinuum generation — the extreme spectral broadening of laser light (a span from the ultraviolet to the mid-infrared is possible) — is a fascinating process that takes place in a dispersive and strongly nonlinear optical medium

Stokes solitons in optical microcavities

Solitons are wave packets that resist dispersion through a self-induced potential well. They are studied in many fields, but are especially well known in optics on account of the relative ease of their formation and control in optical fibre waveguides. Besides their many interesting properties, solitons are important to optical continuum generation, in mode-locked lasers, and have been considered as a natural way to convey data over great distances. Recently, solitons have been realized in microcavities, thereby bringing the power of microfabrication methods to future applications. This work reports a soliton not previously observed in optical systems, the Stokes soliton. The Stokes soliton forms and regenerates by optimizing its Raman interaction in space and time within an optical potential well shared with another soliton. The Stokes and the initial soliton belong to distinct transverse mode families and benefit from a form of soliton trapping that is new to microcavities and soliton lasers in general. The discovery of a new optical soliton can impact work in other areas of photonics, including nonlinear optics and spectroscopy

Coherent master equation for laser modelocking

Modelocked lasers constitute the fundamental source of optically-coherent ultrashort-pulsed radiation, with huge impact in science and technology. Their modeling largely rests on the master equation (ME) approach introduced in 1975 by Hermann A. Haus. However, that description fails when the medium dynamics is fast and, ultimately, when light-matter quantum coherence is relevant. Here we set a rigorous and general ME framework, the coherent ME (CME), that overcomes both limitations. The CME predicts strong deviations from Haus ME, which we substantiate through an amplitude-modulated semiconductor laser experiment. Accounting for coherent effects, like the Risken-Nummedal-Graham-Haken multimode instability, we envisage the usefulness of the CME for describing self-modelocking and spontaneous frequency comb formation in quantum-cascade and quantum-dot lasers. Furthermore, the CME paves the way for exploiting the rich phenomenology of coherent effects in laser design, which has been hampered so far by the lack of a coherent ME formalism