Nonlinear optoacoustics

Sound and light can interact very strongly within small-solid-core PCFs due to simultaneous confinement of light and acoustic vibrations in the tiny core. Highly efficient forward stimulated Raman-like scattering (SRLS) [1] and forward stimulated inter-polarization scattering (SIPS) [2] mediated by transverse acoustic resonances (ARs) trapped in the PCF core can be observed at modest optical powers. Recently, we have demonstrated a reconfigurable all-optical isolator based on optical excitation of a guided acoustic mode in a PCF core [3]. This isolator has remarkable advantages over its passive counterparts, including a large dynamic range of isolation (20 dB, Fig. 2(b)), fast switching capability (< 20 ns, Fig. 2(c)) and reversibility, providing new functionality that is useful in various types of all-optical systems. Incorporating these optoacoustic elements into a ring cavity has allowed us to passively mode-lock a fibre laser at the 337th harmonic [4]. As a PhD student you would get involved in exploring new applications of these fascinating effects.


  1. M. S. Kang, A. Nazarkin, A. Brenn and P. St.J. Russell, Tightly trapped acoustic phonons in photonic crystal fibres as highly nonlinear artificial Raman oscillators, Nature Phys. 5, 276-280 (2009).
  2. M. S. Kang, A. Brenn and P. St.J. Russell, All-optical control of gigahertz acoustic resonances by forward stimulated interpolarization scattering in a photonic crystal fiber, Phys. Rev. Lett. 105, 153901 (2010).
  3. M. S. Kang, A. Butsch and P. St.J. Russell, Reconfigurable light-driven opto-acoustic isolators in photonic crystal fibre, Nature Photon. 5, 549-553 (2011).
  4. M. S. Kang and P. St.J. Russell, 1.8 GHz harmonically mode-locked fiber laser employing Raman-like optoacoustic interactions in PCF, in Nonlinear Photonics (Optical Society of America, Colorado Springs), paper NM4C.6. (2012).

Figure: (a) Principles of unidirectional optoacoustic interactions. Dispersion diagrams of the optical and acoustic modes of PCF are shown. The ARs created by the forward-pump (F-pump) and forward-Stokes (F-Stokes) waves via forward SIPS process do not cause efficient coupling of the backward-pump (B-pump) wave to any other optical mode. (b) Tuning of optical isolation (dynamic range: 20 dB) by adjusting the input control power. (c) Switching of optical isolation (switching time < 20 ns) by turning on and off the control wave.


Dr. Anna Butsch (