Intercore Coupling Effects in Multicore Optical Fiber Tapers Using Magnetic Fluid Out-Claddings

We demonstrate a compact and functional light coupling device based on a multicore optical fiber and a ferrofluidic out-cladding. This magnetic field tuned light coupler was fabricated by tapering down a multicore optical fiber for extending modal profile of the individual cores, while introducing light coupling between them; then, using the ferrofluidic overlayer for affecting the evanescence field of the outer cores through magneto-refractivity. Coupling effects between 2.5 and 4.5 dB were measured between the central core of the multicore fiber and the outer cores, with the application of a magnetic field flux of ~50 G. This intercore coupling photonic device may find application in sensing, communications, imaging, and laser beam delivery.