Department of Physics,School of Science,Changchun University of Science and Technology,Changchun 130022,China
Using single-ring microresonators with loss to realize the light speed control encounters difficulties of heavy light loss and serious pulse distortion. Based on the symmetry between the transfer characteristics of resonators with loss and with gain, the transmission, group index, and group velocity dispersion of a single-ring microresonator are calculated and analyzed. The action mechanism of the loss and gain on the transfer characteristics of the micro-ring resonator is demonstrated. The light speed control behavior of the resonator with gain is calculated and compared with that of the resonator with loss. Calculation results indicate that the resonator with gain can produce the nonsplitted pulses with higher intensities and their pulse delay and pulse advancement are greater than those of the resonator with loss. These results show that the resonator with gain can be used to control the speed of light and to overcome the pulse loss and distortion in dissipative resonators.