  We study arrays of silver split-ring resonators operating at around
1.5-{\mu}m wavelength coupled to an MBE-grown single 12.7-nm thin InGaAs
quantum well separated only 4.8 nm from the wafer surface. The samples are held
at liquid-helium temperature and are pumped by intense femtosecond optical
pulses at 0.81-{\mu}m center wavelength in a pump-probe geometry. We observe
much larger relative transmittance changes (up to about 8%) on the
split-ring-resonator arrays as compared to the bare quantum well (not more than
1-2%). We also observe a much more rapid temporal decay component of the
differential transmittance signal of 15 ps for the case of split-ring
resonators coupled to the quantum well compared to the case of the bare quantum
well, where we find about 0.7 ns. The latter observation is ascribed to the
Purcell effect that arises from the evanescent coupling of the split-ring
resonators to the quantum-well gain. All experimental results are compared with
a recently introduced analytical toy model that accounts for this evanescent
coupling, leading to excellent overall qualitative agreement.
