Discrete photonics in waveguide arrays

Abstract

In homogeneous arrays of coupled waveguides, Floquet-Bloch waves are known to travel freely across the waveguides. We introduce a systematic discussion of the built-in patterning of the coupling constant between neighboring waveguides. Key patterns provide functions such as redirecting, guiding, and focusing these waves, up to nonlinear all-optical routing. This opens the way to light control in a functionalized discrete space, i.e., discrete photonics.

Light-propagation management in coupled waveguide arrays: Quantitative experimental and theoretical assessment from band structures to functional patterns

“…We have shown [14] that mode analysis can be of some help here by pointing out critical points, but GSs can no longer be fully predicted. We have to rely on numerical simulations using eCMT coupled propagation equations, neglecting 033811-7 …”

“…7). Their envelope GS can then be predicted by our model with successions of interface crossings obeying space and phase conservation rules [14] and beam propagations; both can be calculated analytically knowing the band structures. Figure 7(b) shows that prediction is quite correct.…”

“…Their ability to mimic complex systems-atomic or others-with a very small number of elements makes them remarkably fruitful model systems for demonstrating fundamental effects such as quasifree propagation of light, diffraction engineering [1][2][3], Bloch oscillations, quantum mechanical decay, Anderson localization, and Rabi oscillations [4][5][6][7][8][9], as well as routing optical signals [10][11][12]. In a further step, following the introduction of "defects" in arrays [13], we have proposed the systematic patterning of the coupling for engineering the propagation of guided light [14]. Inside this structured metamaterial, wave packets or "beams" can be redirected by interfaces [15,16], guided by channels [17], focused by lenslike patterns, steered by control beams, etc.…”

Controlling the path of discretized light in waveguide lattices

“…Lattice engineering enables to mold in a rather flexible way the flow of discretized light, hence providing altogether new opportunities for applications [8,[12][13][14]. In spite of the discretized behavior imposed by the lattice, light transport in homogeneous waveguide lattices shear some common features with optical beam propagation in homogeneous media (hereafter referred to as continuous beam propagation).…”

“…A similar method holds for discretized beams. Gradedindex waveguide lattices are usually realized by the introduction of an inhomogeneous profile of the propagation constants or of the coupling strengths for the various waveguides [12,14,17], and can find applications in optical steering and focusing [12,14]. For example, plasmonic aperiodic waveguide arrays have been recently proposed to realize deep sub-wavelength focusing and steering [14].…”