We introduce Bloch-wave beatings in arrays of multimode periodically bent waveguides with a transverse refractive index gradient. The new phenomenon manifests itself in the periodic drastic increase of the amplitude of the Bloch oscillations that accompanies resonant conversion of modes guided by the individual waveguides. The Bloch-wave beatings are found to be most pronounced when the length of the resonant mode conversion substantially exceeds the longitudinal period of the Bloch oscillations. The beating frequency decreases when the amplitude of waveguide bending decreases, while the beating amplitude is restricted by the amplitude of the Bloch oscillations that emerge from the second allowed band of the Floquet–Bloch lattice spectrum.
© 2014 Optical Society of America
Original Manuscript: March 24, 2014
Revised Manuscript: April 26, 2014
Manuscript Accepted: May 27, 2014
Published: June 23, 2014
Yaroslav V. Kartashov, Victor A. Vysloukh, and Lluis Torner, "Resonant Bloch-wave beatings," Opt. Lett. 39, 3826-3829 (2014)