A simple structure is proposed to generate slow and fast light simultaneously in a double-waveguide coupled disk
resonator (DCDR) launched with dual contra-propagating inputs. The interaction between the intra-cavity backscattering
and the losses out of cavity are investigated for the disk resonator while random surface defects (backscatters) are
intentionally introduced in the cavity to produce the backscattering. The theoretical investigation done in this work
shows that by adjusting the amplitude and/or phase difference between the dual inputs the interaction between the cavity
modes and backscatters can be controlled thus the transmission and dispersion of the output lights of the system can be
manipulated. This scheme is attractive for slow and fast light tuning applications especially when active tuning elements
such as a p-i-n diode or a heater is absent in the cavity.