  Concomitant amplified spontaneous emission (ASE) and F\"orster resonance
energy transfer (FRET) are investigated in electrospun light-emitting fibers.
Upon dye-doping with a proper FRET couple system, free-standing fibrous mats
exhibit tunable FRET efficiency and, more importantly, tailorable threshold
conditions for stimulated emission. In addition, effective scattering of light
is found in the fibrous material by measuring the transport mean free path of
photons by coherent backscattering experiments. The interplay of ASE and FRET
leads to high control in designing optical properties from electrospun fibers,
including the occurrence of simultaneous stimulated emission from both donor
and acceptor components. All tunable-optical properties are highly interesting
in view of applying electrospun light-emitting materials in lightening,
display, and sensing technologies.
