Figure 1
From: All-fiber few-mode interference for complex azimuthal pattern generation
Experimental setup for complex azimuthal pattern generation: a standard SMF-28 fiber (SMF) is used to launch light from a laser diode (LD, 980nm) and it propagates in a few-mode regime. Interference among the excited modes (\(LP_{01}\) and \(LP_{11}^{a,b}\)) is achieved using a multi-mode interference (MMI) device formed upon splicing a segment of no-core fiber (NCF, length=L) to the SMF (see inset on the right). The energy distribution and relative phases of the excited modes are adjusted by means of a polarization synthesizer (PSY). A microscope objective (OBJ) and a camera (CAM) are used for recording the patterns at the MMI output end (see text for further details). Polarization and energy distribution of the propagated modes are modified by piezoelectric actuators inside the PSY inducing controlled stress on the fiber indicated in the left side inset by orange arrows.
