Integrated multi-port circulators for unidirectional optical information transport.

On-chip photonic networks hold great promise for enabling next-generation high speed computation and communication systems. It is currently envisioned that future integrated photonic networks will be capable of processing dense digital information on a single monolithic platform by involving a multitude of optical components ranging from lasers to modulators, to routers, interconnects and detectors. Among the possible functionalities to be incorporated in such arrangements is the ability to route information in a unidirectional way among N-ports - a capability typically afforded through the use of optical circulators. Yet, in many settings, what is basically needed is re-routing information in a unidirectional fashion without necessarily invoking optical isolation. Of interest would be to devise strategies through which miniaturized optical devices can be monolithically fabricated on light-emitting semiconductors by solely relying on physical properties that are indigenous to the material itself. By exploiting the interplay between non-Hermiticity and nonlinearity, here we demonstrate a new class of chip-scale information transport devices on spatially modified III-V quantum well systems. These unidirectional structures are broadband (over 2.5 THz) at 1550 nm, effectively loss-free, color-preserving, and in proof-of-principle demonstrations have provided 23 dB isolation when used under pulsed-mode conditions at milliwatt (mW) power levels.

Dynamics of accelerating Bessel solutions of Maxwell's equations.

We investigate the propagation dynamics of accelerating beams that are shape-preserving solutions of the Maxwell equations, and explore the contribution of their evanescent field components in detail. Both apodized and nonapodized Bessel beam configurations are considered. We show that, in spite of the fact that their evanescent tails do not propagate, these nonparaxial beams can still accelerate along circular trajectories and can exhibit large deflections. Subsequently, our formulation is extended in other two-dimensional vectorial arrangements. The reported results can be useful in plasmonic and other subwavelength and near-field settings.

Fully vectorial accelerating diffraction-free Helmholtz beams.

We show that new families of diffraction-free nonparaxial accelerating optical beams can be generated by considering the symmetries of the underlying vectorial Helmholtz equation. Both two-dimensional transverse electric and magnetic accelerating wave fronts are possible, capable of moving along elliptic trajectories. Experimental results corroborate these predictions when these waves are launched from either the major or minor axis of the ellipse. In addition, three-dimensional spherical nondiffracting field configurations are presented along with their evolution dynamics. Finally, fully vectorial self-similar accelerating optical wave solutions are obtained via oblate-prolate spheroidal wave functions. In all occasions, these effects are illustrated via pertinent examples.

Observation of Bloch-like revivals in semi-infinite Glauber-Fock photonic lattices.

We report the first experimental implementation of Glauber-Fock oscillator lattices. Bloch-like revivals are observed in these optical structures in spite of the fact that the photonic array is effectively semi-infinite and the waveguide coupling is not uniform. This behavior is entirely analogous to the dynamics exhibited by a driven quantum harmonic oscillator. Our observations are in excellent agreement to the analytical results obtained in this fully integrable lattice system.