  Colloidal 2D semiconductor nanoplatelets are highly efficient light emitters,
which exhibit large absorption and emission cross sections, and constitute
promising laser gain media. However, if dispersed in solutions, such
nanoplatelets lack a suitable optical platform for scalable and
application-oriented integration into optical setups such as lasers. Here, we
demonstrate the first successful integration of solution-processed 2D CdSe/CdS
Core/Crown nanoplatelets in m-scale liquid core optical fibers. We compare the
nanoplatelets' spectroscopic properties before and after filling them into the
fibers and find that spontaneous emission is shifted and broadened. We even
observe a first evidence of stimulated emission at high excitation energies. In
conclusion, liquid core fibers constitute a novel and scalable platform for
optical integration of nanoplatelets for applications as novel, highly
reconfigurable laser gain medium.
