Key Technology For Optical Code Division Multiple-Access And Tunable Optical Pulse Generation

With the expands of multimedia,Internet and B-ISDN, the increasing demand has been presented for higher communication capacities and more quickly transmission speed, all optical communication has become the develop target of optical communication, and all optical local area network is one of research issues of optical communication. In this paper, two part work has been presented: 1) the technology of optical code-division multiple access (OCDMA) encoding/decoding based on fiber Bragg grating has been studied; 2) pulse injection seeding for single and dual wavelength optical pulse generation using semiconductor laser has been studied experimentally.1 Research of OCDMA encoding/decoding based on step chirped fiber gratingA spectral phase optical code-division multiple-access (OCDMA) encoder /decoder based on step chirped fiber Bragg Gratings (SCFBGs) is developed.A method is proposed for realizing OCDMA encoding/decoding in step chirped fiber Bragg grating by mapping the m sequence address code. Simulation result for encoder/decoder shows good correlation as expected. The factors influencing correlation property is also discussed.The performance for OCDMA system based on SCFBGs encoder/decoder is analyzed. The method for fabricating SCFBGs is introduced, and principle and parameters of mask for SCFBG is also introduced.2 Generation for electrically single wavelength tunable optical pulse in pulse injection seeding schemeA method for electrically wavelength tunable optical short pulses generation by pulse injection seeding is developed, with which a Fabry-Pérot (F-P) laser diode combined a tunable filter and an erbium-doped fiber amplifier (EDFA) is used as the external-injection seeding light source. The side mode suppression ratio (SMSR) achieved is better than 25 dB over the wavelength tuning range of 9 nm. The system is simple and of low cost. A simple and robust system is developed to generate electrically wavelength tunable optical short pulses by the use of two gain-switched F-P laser diodes in a mutual pulse injection seeding scheme. The side mode suppression ratio achieved by the system is larger than 26 dB over the wavelength region of 25 nm. A mutual pulse injection-seeding scheme is first proposed to produce electrically wavelength tunable optical short pulses by the use of two F-P laser diodes, of which one is gain-switched and the other is DC biased. The side mode suppression ratio obtained is more than 30 dB over the wavelength tuning rang of 19 nm. The system is simple and robust. The repetition frequency is about 3.0 GHz.3 Generation for dual wavelength tunable optical pulse in pulse injection seeding schemeA mutual pulse injection-seeding scheme is developed to generate tunable dual-wavelength optical short pulses by the use of two gain-switched F-P laser diodes. The sidemode suppression ratio of the output pulses is better than 25 dB over a wavelength-tuning range of 13.2 nm. The system is robust and convenient for wavelength-tuning.A mutual pulse injection-seeding experiment scheme of gain-switched F-P laser diodes combined DC biased one is developed for tunable dual-wavelength optical short pulse generation. The sidemode suppression ratio of the output pulses achieved is better than 25 dB over the wavelength-tuning range of 12.1 nm. The system is robust, flexible and convenient for wavelength tuning.