Research On UDWDM-PON Transmitter And Microwave Frequency Multiplication System Based On Injection Locking

As the "last mile" of optical fiber communication,optical access network(OAN)is one of the most important technologies which determines the service quality.At present,the access methods are mainly divided into two types: wired access such as passive optical network(PON)technology,and wireless access such as Wi-Fi.The former one has lager access bandwidth,while wireless access performs better in terms of flexibility and convenience.With the growth of network scale and user bandwidth,existing access technologies are facing a huge challenge: satisfy bandwidth requirement and access convenience while user scale is expanding.Based on above background,this work mainly includes following contents: 1.Ultra-dense wavelength division multiplexing-passive optical network(UDWDM-PON)transmitter solves the problem that user wavelength is difficult to synchronize in the existing technologies;2.In the aspect of optical/wireless hybrid access,the technology of microwave frequency multiplication based on injection locking is studied,and the low-cost realization of broadband wireless transmission on the client side is explored to ensure the convenience of user access.In terms of UDWDM-PON network,this paper presents the concept of wavelength synchronization,and a wavelength synchronization UDWDM-PON transmitter scheme based on injection locking is proposed.The multi-wavelength optical source is used to provide channel reference for the whole access network,which ensures the relative stability of channel interval.The comb is injected into semiconductor lasers to separate the wavelength reference.Then the uplink and downlink user carriers are alternately distributed,which is helpful for the synchronization of uplink user carriers.Active filtering is used at the receiver to recover the uplink carriers and realize wavelength synchronization of the whole network.In order to ensure the stability of wavelength synchronization in the access network,wavelength reference automatic locking and tracking are studied.The wavelength of semiconductor laser is controlled by detecting the feedback power of beat signal after injection locking,and the channel reference of main optical source is tracked automatically.As a verification,an 8-channel synchronous UDWDM-PON transmitter with a channel spacing of 5 GHz has been realized.In the aspect of optical/wireless hybrid access,a new scheme of microwave frequency multiplication system based on injection locking of directly modulated laser is proposed in this paper,which avoids the use of expensive high-speed photoelectric receiver and effectively reduces the system cost.The specific scheme is to inject the low-frequency signal light into the directly modulated laser.By utilizing the interaction characteristics between the intensity of the light field and the carrier concentration in the injected directly modulated laser,the frequency multiplication signal is obtained directly at the radio frequency(RF)port of the directly modulated laser.Theoretical analysis and experimental verification of the scheme are carried out in this paper respectively.The 10-times and 12-times microwave signals of basic frequency are obtained at RF port of the directly modulated laser,which has verified the feasibility and flexibility of the proposed scheme.