The Research On Generation Technology And Application Of Multicarrier Light Source

Microwave photonics combines the flexibility of microwave wireless communications and the advantage of the broad bandwidth of optical communication.As a new crossed area,it has great potential for development.Microwave photonics focuses on microwave signals and optical signals how to interact with each other.Multi-carrier optical communication has strong anti-multipath capability,high transmission capacity and good anti-narrowband interference performance.The application of multi-carrier light source in multi-carrier optical communication system can not only reduce the cost and the complexity but also improve the stability of the system and it has a certain value of research.Therefore,it has become the current research hotspot that how to generate multi-carrier light source with many carriers,adjustable spacing,high tone-to-noise,flatness and good stability.This paper focuses on the generation of the multi-carrier light source based on electro-optic modulator and its application in a point-to-point wavelength division multiplexing?WDM?system.By studying the basic principle of electro-optic modulator method,a new scheme of generating multi-carrier light source based on dual parallel Mach-Zehnder modulator?DPMZM?is proposed.First,a flexible and flat multi-carrier light source generator utilizing a single DPMZM is detailed investigated both in theory and experiment.In the scheme,the two sub-modulators of DPMZM are biased at the maximum and minimum working points respectively,and the bias voltage of the main modulator is set to zero.By adjusting the RF signals power,two multi-carrier light sources with even harmonics or odd harmonics can be generated.So at the end of DPMZM,5 and 7-line flat multi-carrier light sources with a flatness of less than 1 dB and a side-comb suppression ratio?SCSR?higher than 18 d B are theoretically and experimentally generated.This scheme is relatively simple and its stability is better because only one bias voltage may be controlled.Then,on the basis of this scheme,two new generation schemes of multi-carrier light source based on cascade structure are proposed.Among them,the scheme one utilizes two cascaded DPMZMs and generates a flat multi-carrier light source with 25,35 and 49 lines.The scheme two utilizes cascaded DPMZM and intensity modulator?IM?and generates a flat multi-carrier light source with 25 and 35 lines.These two schemes are relatively simple to implement because of fewer control variables,and the generated multi-carrier light source has good flatness,a large number of lines and the adjustable spacing.The performance of the two proposed schemes is studied and analyzed both in theory and simulation.Finally,we obtain a 7-line multi-carrier light source based on a single DPMZM and regard it as a light source,and construct a point-to-point WDM communication system.The system is simulated by VPI,and it provides a single-wave transmission rate of 10 Gbps digital information.The bit error rate?BER?of the system is less than 10^-40 after 40 km standard single mode fiber?SSMF?transmission.