10388

9583

كارشناسي ارشد

الكترونيك

اصفهان: دانشگاه صنعتي اصفهان، دانشكده برق و كامپيوتر

1394

نه، 74ص.: جدول، نمودار

اصغر غلامي

مسعود عمومي

1394/06/02

1396/10/04

كتابنامه

برق و كامپيوتر

مهندسي برق و كامپيوتر

ID9583

به فارسي و انگليسي

81 Design and implementation of narrow linewidth fiber laser Nastaran Pourshab Nastaran pourshab@yahoo com 26 05 2015 Department of Electrical and Computer Engineering Isfahan University of Technology Isfahan 84156 83111 Iran Degree M Sc Language Farsi Supervisor Asghar Gholami gholami@cc iut ac ir Abstract Narrow linewidth single frequency fiber lasers have potential application inwavelength division multiplexing DWDM communications coherent laser radar highresolution spectrum analysis and various fiber optical sensors In recent years theimportance of the laser s Coherent length in some application such as rangefinder hasattracted much attention to narrow linewidth fiber lasers By decreasing the laser outputlinewidth the coherent length of the laser increases In many applications such asrangefinder a laser with linewidth in the order of kHz is needed The simplest way torestrict the number of modes is to include a bandwidth limiting element in the cavity Oneconvenient element is using fiber bragg grating however the price of the fiber bragggrating is too expensive Recently Fabry Perot fiber laser with short cavity length isdemonstrated as narrow linewidth fiber laser Due to their short length these lasers sufferfrom a low pump absorption and hence low slope efficiency Alternatively narrow linewidth fiber laser can be obtained using travelling wave rings They have potentially high slope efficiencies Owing to the long cavity lengths they alsogive narrow linewidths Unfortunately they are susceptible to mode hopping To suppressmode hopping narrow linewidth filters were used It has been shown that standing wavesaturation effects in un pumped erbium doped fiber can be used to establish narrow bandreflection filters More recently an un pumped PM erbium doped fiber was incorporatedtravelling wave ring as a saturable absorber to establish linewidth narrowing In this research we investigate different method and based on the simulation resultsand the available components a proper method is selected to implement a narrowlinewidth fiber laser In this method Compound sub rings because of simple design andhigh efficiency as a filter for decreasing the linewidth is used The effect of differentparameters such as the length of active medium pumped power dopingconcentration on the linewidth and operation of the laser analyzed Then themeasurement results is presented and compared with simulation results Finally ourimplemented fiber laser with sub rings has a linewidth of less than 1kHz

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