ONR YIP: Topological Protection in Time-Reversal Invariant Photonic Devices

Optical devices are essential ship-based naval technology. Examples of such applications include (but are not limited to) wavelength division multiplexers that allow for high-speed, high-bandwidth communications; fiber-based sensors for highly advanced submarine ???periscopes???, and optical chip-based precise time keeping. It is essential for these devices to be as small, light and power-efficient as possible for incorporation into ship-based systems. However, the smaller the device, the more expensive the fabrication and the more susceptible it is to inevitable fabrication imperfections. Recently, a novel concept called ???topological protection??? has shown to give rise to exceedingly robust transport of light through a range of devices, from silicon chips to optical multimode fibers, to microwave metamaterials, and others. Topological protection means that the transport of light is related not to specific details of the system???s geometry, but rather to aglobal topological number that characterizes the device as a whole. This means that defects and disorder cannot diminish the device???s performance. This in turn implies that devices can be made smaller and cheaper to produce.Here, three approaches to demonstrating topological protection in realistic devices are proposed: (1) using ???valley Hall??? and ???topological crystalline insulator??? systems to demonstrate topologically protected transport on the edge of silicon photonic crystal structures and multimode laser-written waveguide arrays; (2) using crystalline insulator protection to demonstrate protected cavity modes for efficient coupling to quantum emitters and enhanced nonlinearity; and (3) using ???topological pumping??? to prevent light from getting Anderson localized (i.e., trapped by disorder) within a device. Each of these approaches will allow for highly robust device design that has the potential to improve performance and/or reduce cost of optical devices essential to ship-based communications, sensing, and computing.