The Propagation Properties Of Broadband Pulses

Light is easy to acquire and less susceptible to the interference from the enviroment, which makes it an ideal carrier for quantum information, thus, the control of signal light is of great importance in the region of communication. With electromagnetically induced transparency (EIT), a weak signal field at a particular frequency can propagate without dissipation and loss but with a substantially reduced group velocity, which can realize slow-light experiments and light-storage. EIT has received much attention due to it promising application potential in quantum coherent control, enhancement of nonlinear optical processes, and quantum information and memory. An EIT medium placed in a cavity can substantially affect the properties of the resonator system and significantly narrow the cavity linewidth. Ultranarrow spectral linewidth can be observed, which has a promising application in frequency stabilization and high-resolution spectroscopic measurements. Researching about the dispersion properties can be applied to the control of the cavity linewidth, and design novel optoelectronics devices, such as optical switches and filters.The propagation of broadband pulse in a medium is studied first in our work. The results show that if the carrier frequency of pulse is exactly tuned to the center of the transparency window, and the pulse spectrum is broader than transparency window, the pulse is temporal broadened and the delay effect is significant; If the carrier frequency of pulse is exactly tuned to the region of absorption, and the pulse spectrum is wide with respect to the width of absorption line, the pulse begins to distort after a certain distance and it is split into two parts at last, the peak value not only depend on the frequency and intensity of the coupling field, but also the length of the sample.Second, we study the transmission of intracavity and the propagation property of pulse in intracavity. We use the interference of lights to explain the cavity transmission, the position and the linewidth of central peak. The results show that there is a three-peaked spectrum consisting of two broad sidebands and a narrow central peak. The linewidh is mainly affected by intracavity dispersion properties:the narrow spectral linewidth can be achieved by decreasing the intensity of coupling field, the position of central peak can be adjusted by altering frequency of coupling field, thus achieve the control of the frequency of cavity. We also show that the propagation property of pulse in intracavity is affect by three-peaked spectrum obvious, the number of pulse's peaks can be controlled by the intensity of coupling field.