  The creation of nanoscale lasers that operate above a coherent threshold is a
challenging problem. We propose a way to circumvent this issue using systems in
which a strong coupling regime is achieved between the light and the active
medium. In the strong coupling regime, energy oscillations take place between
the EM field in the cavity and the atoms. By applying appropriate time
modulation to the pumping, it is possible to control these energy oscillations
in such a way that coherence in the laser system appears below the lasing
threshold. We show that in this approach, the radiation linewidth is two orders
of magnitude smaller than the linewidth of a conventional laser for the same
photon number. In addition, the second order coherence function of the output
radiation is reduced from two to one before the system reaches a positive
population inversion. Our results pave the way for the creation of nanoscale
sources of coherent radiation that can operate below the lasing threshold.
