  Semiconducting single-walled carbon-nanotubes (SWCNTs) are an interesting
material for strong-light matter coupling due to their stable excitons, narrow
emission in the near infrared and high charge carrier mobilities. Furthermore,
they have emerged as quantum light sources as a result of the controlled
introduction of luminescent quantum defects (sp$^{3}$-defects) with red-shifted
transitions that enable single-photon emission. The complex photophysics of
SWCNTs and overall goal of polariton condensation pose the question of how
exciton-polaritons are populated and how it might be optimized. The
contributions of possible relaxation processes, i.e., scattering with acoustic
phonons, vibrationally assisted scattering, and radiative pumping, are
investigated using angle-resolved reflectivity and time-resolved
photoluminescence measurements on microcavities with a wide range of detunings.
We show that the predominant population mechanism for SWCNT exciton-polaritons
in planar microcavities is radiative pumping. Consequently, the limitation of
polariton population due to the low photoluminescence quantum yield of
nanotubes, can be overcome by luminescent sp$^{3}$ defects. Without changing
the polariton branch structure, radiative pumping through these emissive
defects leads to an up to 10-fold increase of the polariton population for
detunings with a large photon fraction. Thus, the controlled and tunable
functionalization of SWCNTs with sp$^{3}$ defects presents a viable route
towards bright and efficient polariton devices.
