Optical Gain in the Near Infrared by Light‐Emitting Electrospun Fibers

The potential integration of polymer nanofibers in photonic devices and circuits is a major driver for research on their waveguiding and optical gain properties. Emission in the near‐infrared is especially important in this framework in view of the realization of nanofiber‐based optical amplifiers. Here, the optical gain properties of electrospun fibers embedding near‐infrared light‐emitting molecules are investigated. Upon pulsed optical pumping, line narrowing typical of amplified spontaneous emission is observed, with gain of 5.5 cm^?1 and threshold fluence down to 0.25 mJ cm^?2. Importantly, the stimulated emission characteristics are strongly dependent on individual fiber characteristics and on the mutual alignment of nanofibers in arrays, thus being tailorable through the fiber architecture and assembling. These results open interesting perspectives for the exploitation of electrospun fibers as active components in the near‐infrared range.