Study On The Applications And Fabrication Of EDFA Flattened By Chirped Fiber Gratings

Optical fiber communication is the most active technology ofcommunication field. Optical fiber communication, satellite communicationand mobile communication are the three main orientations of moderncommunication technology. At present, plenty of communication businesscontinuously emerges, especially fast development of Internet induces rapidincrease of communication capacity. Thus, it is necessary to establishlarge-capacity and high-speed optical fiber communication system. Fibergratings provide possibilities for the further development of large-capacity andhigh-speed optical fiber communication system. Fiber grating is a new kind ofall-fiber passive device that results from that the refractive index of opticalfiber core is periodicity microperturbation. Because of the excellent propertiessuch as compatible with optical fiber, easy fabrication, little insert loss, smallvolume and low price, fiber gratings have wide application in optical fibercommunication and sensor field. Thus, since the successful fabrication of firstfiber grating, the fabrication and application of fiber gratings is central issue ofinterest all along.Chirped fiber grating is one type of fiber gratings whose optical period(product of grating's effective refractive index and refractive indexmicroperturbation's period). Light with different wavelength is reflected ataxial different point of chirped fiber grating. So chirped fiber gratings havebroad reflection bandwidth. The group delay in chirped fiber grating reflectionbandwidth changes gradually. These properties are what other type fibergratings do not have. It is these unique properties that make chirped fibergratings have unique applications both in optical communication and sensorfield, such as filters and dispersion compensators. The work of this thesis is deeply studying the principle, fabricationproperties and applications of chirped fiber gratings. In respect of theory, we strictly deduced couple mode theory that describethe principle of fiber gratings from Maxwell equation, and analysis theproperties of chirped fiber grating, obtain the relation between chirped fibergrating's parameters such as change of refractive index, length and chirp aswell and the properties such as reflectivity, bandwidth and dispersion. All ofthese prepare for the design and fabrication of the nonlinearly chirped fibergratings. We give s using phase mask methods for the fabrication of chirped fibergratings. The method of using chirp phase mask, which is the normal method forfabricating fiber gratings. After analyzing the relation of the period of maskand the period of fiber gratings, we got the basic method of design phase maskfor nonlinearly chirped fiber gratings. High quality chirped fiber gratings were fabricated by the method ofusing phase mask, in which we used a chirped phase mask and once scanningexplore technique to fabricate chirped fiber gratings. In experiment, a 100-mmapodized linearly chirped fiber grating was obtained that has more than 99%reflectivity, linear group delay in reflection bandwidth of 0.4nm, dispersion ofabout -2403ps/nm, ripple of delay of less than +/-20ps. The method of usingphase mask has many virtues such as the easy process of fabrication, the goodconsistency and the easy control in fabricating. The drawbacks of this methodare that the mask is too expensive and the bandwidth of fiber gratings isdifficult to change. It is smooth to take in WDM can be improved and gained bandwidth andall passways of capacity of the systemming for EDFA to gain, in all bandwidthgaining smooth to is it can improve different passway difference that appeargain to take inside, the transmission that can be avoided in the field of lightproduced by electricity in all mere structure losses. So, it is very importanttechnology that EDFA is gained and melted smoothly in thephoto-communication. This kind of reflectivity wave filter makes the principleas follows: Reflection rate of the corresponding different wavelength ofdifferent positions of length direction of the grating along warbling , throughregulate different reflection rate of position , can get with specific transmissionof wavelength lossing reflection spectrum matched to demand. Use as whengaining smooth, the wave filter is it transmit mode to work , can manufacturewith compatible standard form mould optic fibre, it will be very low to soweld lossing when if SMF-28 is joined with the ordinary optic fibre. Is itdesign protect simply gain smooth EDFA , can select for use panda type oroval core type is it lean towards optic fibre write into the grating to assuare toneed. And, as the whole optic fibre device, inserts and decreases and is lowerthan 0 outside the wave band. 1dB, and mainly that it is caused that therefracting rate changes while writing into the optic fibre purple outside.Anneal craft guarantee stability of device , can make one one year such as...