List of Division publications with links

2016-05-30 10:34 - Resolving the mystery of milliwatt-threshold opto-mechanical self-oscillation in dual nanoweb fiber

J. R. Koehler, R. E. Noskov, A. A. Sukhorukov, A. Butsch, D. Novoa, and P. St.J. Russell, APL Photonics 1, 056101 (2016)

It is interesting to pose the question: How best to design an optomechanical device, with no electronics, optical cavity or laser gain, that will self-oscillate when pumped in a single pass with only a few mW of single-frequency laser power? One might begin with a mechanically resonant and highly compliant system offering very high optomechanical gain. Such a system, when pumped by single-frequency light, might self-oscillate at its resonant frequency. It is well-known, however, that this will occur only if the group velocity dispersion of the light is high enough so that phonons causing pump-to-Stokes conversion are sufficiently dissimilar to those causing pump-to-anti-Stokes conversion. Recently it was reported that two light-guiding membranes 20 µm wide, ~500 nm thick and spaced by ~500 nm, suspended inside a glass fiber capillary, oscillated spontaneously at its mechanical resonant frequency (~6 MHz) when pumped with only a few mW of single-frequency light. This was surprising, since perfect Raman gain suppression would be expected. In detailed measurements, using an interferometric side-probing technique capable of resolving nanoweb movements as small as 10 pm, we map out the vibrations along the fiber and show that stimulated intermodal scattering to a higher-order optical mode frustrates gain suppression, permitting the structure to self-oscillate. A detailed theoretical analysis confirms this picture. This novel mechanism makes possible the design of single-pass optomechanical oscillators that require only a few mW of optical power, no electronics, nor any optical resonator. The design could also be implemented in silicon or any other suitable material.

http://dx.doi.org/10.1063/1.4953373]