| Narrow linewidth single frequency(SF)fiber laser sources,due to their excellent monochromaticity,outstanding stability and coherence,exhibit promising potentials in a large amount of fields such as Doppler LIDAR,gravitational wave detectors,high resolution sensing,optical fiber sensors,coherent telecommunication and precision measurement over the past decades.In this Letter,we devise a novel SF Yb-doped all-fiber master oscillator power amplifier(MOPA)laser at 1064.3 nm.A ring cavity SF fiber laser is used as the seed source for the MOPA system and the Yb-doped fibers are employed as the gain medium or dynamic narrowband filter.In addition,high stability wavelength-tunable SF ytterbium-doped all-fiber compound ring laser has been demonstrated experimentally.By controlling the wavelength of fiber optical tunable filter(FOFT)through the computer,the central wavelength of the generated SF fiber laser is tuned.The high-finesse ring filter(HFRF)and loop mirror filter(LMF)are used to effectively suppress multi-longitudinal mode.The main work and research of this thesis as belows:1.According to the principles of lasers,the formulas of threshold power,slope efficiency and output power of the Yb-doped traveling-wave cavity fiber laser are derived.The general factors influencing the Yb-doped ring cavity fiber laser have been analysed and simulated correspondingly.The relations between performance parameters which consist of threshold power,output power and gain and structure parameters which encompass pump power,fiber length,output coupler rate of fiber laser have also been researched.The results indicate that the adoption of the ring structure parameters has significant ways to optimize the design of the laser.2.The seed laser is composed of a fiber ring cavity,an unpumped YDF and a FBG,without any polarization controller in the cavity.The SF operation is observed to be stable without mode hopping.The maximum average output power of the seed laser is up to 6 mW when the pump power is increased to 260 mW,the slope efficiency is 2.93%,and the instability of the output power is below 2%.The maximum output power of the SF-MOPA laser is about 270 mW at 1064.3 nm with a pump power of 400 mW at 980 nm,the slope efficiency is 66.2%,the SNR is higher than 45 dB,and the linewidth is approximately 1 kHz.The stability(wavelength variation)of the wavelength for 60 min with an interval of 5 min at the room temperature is less than the 0.02 nm.When the pump power is 150 mW,a relaxation oscillation peak with frequency of about 63 kHz occurs.Compared with the received noise,there are no additional noise components observed for frequencies up to 1 MHz.3.The compound ring cavity of a high stability wave length-tunable SF ytterbium-doped laser source is constructed with a FOTF,a HFRF and a LMF.The central wavelength of our SF fiber laser is tuned continuously by the FOTF and the HFRF and LMF in the cavity guarantee the SF operation.Three segments of ytterbium-doped fibers are employed as the gain medium or dynamic narrowband filter,respectively.SF operation is observed to be stable during 2 h without mode hopping.The SF fiber laser achieves a wide-band tunability from 1030 nm to 1090 nm with maximum output slope efficiency of 7.95%at 1075 nm and optical signal to noise ratio(OSNR)of more than 50 dB.The wavelength shift and OSNR fluctuation at 1060.58 nm is less than 0.02 nm and 0.22 dB,respectively.The average linewidth is 8.8 kHz and the relaxation oscillation frequency is at 62 kHz.At the same time,we finally carry out the theory and simulation of the high finesse ring filter and loop mirror filter. |
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