Artificial retinal glial-like waveguides for biomimetic volume optics

In the vertebrate eye light must be funnelled through a mangled mass of scattering tissue by Muller cells [1]. In distinction to conventional waveguides, that are essentially tubular, these cells have a double-funnel shape, and can efficiently focus, collect, transfer, and outcouple light without the strong mode selectivity of waveguides. Here we explore the use of biologically inspired funnel index of refraction patterns that mimic retinal Muller cells as versatile volume blueprints for multiple optical functions [2]. Compared to tube-like patterns typical of soliton-based waveguides, funnels are fully three-dimensional structures (illustrated in Fig. 1(LEFT)) that achieve either focusing, guiding, and defocusing: the key ingredient is the changing shape along the propagation direction (say the z axis) that can, depending on circumstances, act as a lens (the cellular 'end-feet'), or as a fiber (the cellular 'body'), thus forming a basic blueprint to multifunctional optics.