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Analysis And Applications Of Broadband Spectrum、Ultra-wide Tunable Temporal Square-wave Pulse

Posted on:2013-02-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:X M ZhangFull Text:PDF
GTID:1228330377451837Subject:Optics
Abstract/Summary:PDF Full Text Request
Fiber lasers have been applied in scientific research and industrial production such as optical frequency comb, micro-machining, optical sensors and so on. Time domain and frequency domain is the important properties of the fiber laser, related to the specific application of the fiber lasers. Therefore, the study of the characteristics is great significance in terms of the academic and industrial applications. In this thesis, the analysis and applications of broadband spectrum、ultra-wide tunable temporal square-wave pulse is the major works, including the flat broadband spectrum and square-wave pulse fiber laser with temporal ultra-wide tuning range, the widely tunable fiber laser application for fiber Bragg grating (FBG) sensor system.The major works of this thesis are as follows:1. Normal dispersion and anomalous dispersion passively mode-locked broadband spectrum fiber laser is experimentally studied based on nonlinear polarization rotation (NPR) technology. In normal dispersion the generated mode-locked optical spectrum is rectangular shaper with42nm; in anomalous dispersion the noise-like mode-locked pulse is generated with3dB width of102nm.2. A flat supercontinuum is generated with noise-like pulse pumping in highly nonlinear fiber (HNLF). A flat and broad spectrum extending from1000nm to beyond1750nm is obtained. Theoretical analysis based on the generalized nonlinear Schrodinger equation is presented, which qualitatively agrees with the experimental result. The results show that noise-like pulses of a passively mode-locked erbium-doped fiber have potential for generating broad and ultra-flat supercontinuum.3. An ultra-wide tunable square-wave pulse fiber laser is proposed and demonstrated. The square-wave pulsewidth can be tuned in an ultra-wide range of more than1700ns (10-1716ns) by simply increasing the pump power. The pulsewidth tuning is5.1ns/mW. Experimental results and theoretical model show that the fiber nonlinearity plays an important role in the tuning range and peak power of the output pulsewidth.4. A programmable wavelength widely tunable Er-doped fiber laser is demonstrated. The tunable range can cover above51nm (1516.8-1568.3nm) controlled by software and tunable step is up0.01nm. The laser and fiber Bragg grating (FBG) make up quasi-distributed temperature sensing system, which is applied in power system to achieve real-time temperature of16fibers channels, a total of48monitoring points.The innovative work and results in this thesis are as follows:1. An ultra-wide tunable square-wave pulse fiber laser is proposed and demonstrated. The square-wave pulsewidth can be tuned in an ultra-wide range of more than1700ns (10-1716ns) by simply increasing the pump power. The pulsewidth tuning is5.1ns/mW. Experimental results and theoretical model show that the fiber nonlinearity plays an important role in the tuning range of the output pulsewidth. The high nonlinearity helps to increase the tuning range of the pulsewidth.2. Theoretical analysis based on the generalized nonlinear Schrodinger equation (GNLSE) is presented, which shows noise-like pulses of a passively mode-locked erbium-doped fiber have potential for generating broad and ultra-flat supercontinuum. Experimentally, a flat supercontinuum extending from1000nm to beyond1750nm is generated with noise-like pulse pumping in highly nonlinear fiber (HNLF). Especially, in the blue side of the generated spectrum, the intensity fluctuation is within2dB in420nm (from1020nm to1440nm).3. A programmable wavelength widely tunable Er-doped fiber laser is demonstrated, which is applied to fiber Bragg grating (FBG) sensor system to achieve real-time temperature of16fibers channels, a total of48monitoring points.
Keywords/Search Tags:fiber laser, supercontinuum, square-wave pulse, fiber bragggrating (FBG) sensor
PDF Full Text Request
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