Study On All-Optical Wavelength Conversion Based On Fiber Ring Semiconductor Lasers

The age of information demands a transport network with great capacity. Wavelength division multiplexing (WDM) all-optical communication network,which utilizes the enormous bandwidth and excellent transport performance of optical fiber,is very promising. All-optical wavelength converters are expected to become key components in it. They are widely used in optical switching,wavelength routing,wavelength reuse,etc. The employment of them can increase the capacity of WDM network greatly,avoid wavelength competition and make the management of communication network more flexible and rational.Researchers in many countries have extensively studied all-optical wavelength converters and several technologies have been developed. Each of them has its advantages and shortcomings. But up to now,none of them are commercially available. Among these technologies,wavelength converters based on cross-gain modulation,cross-phase modulation and four-wave mixing in semiconductor optical amplifier is the mainstream of research.The paper presents a new scheme of wavelength conversion,which based on fiber ring semiconductor lasers (FRSL). Its configuration and operating principle are demonstrated. On the basis of rate equations of FRSL,power characteristics and extinction ratio of the converted light are discussed. The relation between relaxation oscillation,small-signal modulation response,modulation bandwidth and the length of fiber ring cavity is analyzed also. The results show that there is a critical value of the length of ring cavity with certain parameters. Only when the length of ring cavity is below that value,relaxation oscillation happens,and FRSL have good modulation response and large modulation bandwidth. Theoretical simulation and experiments are done to study wavelength conversion based on FRSL.The wavelength converter based on FRSL has simple configuration. Only signal light is essential at input port,and continuous wave used as pump light in other wavelength converters is not needed. Besides,it is convenient to insert control components in the fiber ring cavity. But it surfers from inversion of the converted bit stream and low conversion rate caused by long fiber ring cavity. Therefore,it issuitable for low speed occasion. It will be more promising if it can be integrated into one component.