Fabry-Perot Filters And Fiber Grating Filters

With the development of the optical fiber communication, microelectronics and computer technology, Internet has been developing at an unprecedented speed, while the basis of sustaining Internet is optical fiber communication. Being key components of optical fiber communication, Fabry-Perot filters and fiber grating filters have been applied in optical sources, WDM multiplexing and de-multiplexing, and add-drop multiplexing, wavelength routers, optical switching of all optical network etc., which greatly promote the advance of high .speed optical communication technology. It can be expected that Fabry-Perot filters and fiber grating filters will still play important roles in future all optical communication systems.Following the rapid increase of the data transmission rate of optical fiber communication, the time slot confined by the time interval of the two successive signals is greatly shortened. Under this circumstance, the effect of the Fabry-Perot filter to a short pulse signal may affect the following short pulse signals. Therefore, studies on the influence of a Fabry-Perot filter on an ultra-short optical pulse are of momentous current significance. In this paper, after adopting the plane wave approximation, taking into account the fact that the output from a Fabry-Perot is formed on the basis of the interference of the multi-reflected beams of the input pulse that enters the filter, an analytical expression of the output pulse intensity has been derived. As a result, the peak power, pulse width and time delay of the output pulse have been investigated in detail, including the chirp of the input pulse and the lineardispersion of the filter, and some new and important conclusions have been obtained for the first time.Using the couple mode theory, the reflection spectrum, the peak reflectivity and the reflection bandwidth of several typical fiber grating filters have been theoretically analyzed and numerically simulated. As a result, a theoretical model of fiber grating external cavity semiconductor lasers including the reflectivity distribution of fiber grating has been presented in this paper. Based on the model, the laser characteristics such as the threshold current, mode suppression ratio etc. have been specified.