  We propose to use frequency-selective quasi parity-time symmetry to reduce
the heat generated by coherent anti-Stokes Raman scattering (CARS) reversed
cycles in active Raman media with phase mismatch. This is accomplished using a
coupled-waveguide structure, which includes the active Raman waveguide (RW),
where the Stokes signal undergoes amplification via stimulated Stokes Raman
scattering (SSRS), and a dissipative waveguide (DW), which is tuned to the
anti-Stokes wavelength so as to evacuate the corresponding anti-Stokes photons
from the RW by coupling. The DW introduces optical loss that partially offsets
the growth of the anti-Stokes signal in the RW and hence suppress the reversed
CARS cycles that would otherwise result into heat generation in the RW. It is
shown that the frequency-selective quasi parity-time symmetry provided by the
DW can reduce the heat in active Raman media by a very factor of up to five
when the CARS phase mismatch is compensated for by the optimum level of
coupling between the RW and the DW.
