  We present a detailed study of electrical and optical generated free carrier
on the spectral characteristics of a silicon microring modulator. The spectral
distortion generated due to thermal and free carriers is presented, and the
mechanism for mitigation is also presented. We observed that two-photon induced
nonlinearity could be addressed by operating the modulator at suitable bias
points. Furthermore, by applying small-signal drive the spectral distortion can
be restored. We also present the effect of optical power and drive signal limit
on the spectral characteristics. The study allows one to identify suitable
device performance and operating conditions to utilize silicon ring modulator
for optical signal processing.
