Research On Multi-wavelength Erbium-doped Fiber Laser Employing A Triple-core Photonic Crystal Fiber Filter

With the rapid evolution of large-capacity optical fiber communications,the system of wavelength division multiplexing(WDM)has become an indispensable part of communication transmission.New requirements for lasers who could provide stable light sources have been put forward by the increasing development of WDM systems.Singlewavelength lasers will gradually be replaced by multi-wavelength lasers,multi-channel light sources will take the place of single-channel light source simultaneously.In addition,high-performance multi-wavelength lasers have also been widely used in masses of fields,such as: spectral analysis,biomedicine,optical fiber sensing and so on.Taking the design of high-performance fiber filters as a breakthrough,the research on stable,switchable and tunable multi-wavelength erbium-doped fiber lasers(MW-EDFLs)has been carried out.The main research results obtained by this thesis are as follows:(1)Based on a segment of triple-core photonic crystal fiber,a in-line triple-core photonic crystal fiber Mach-Zehnder interference is proposed.The structure of triple-core photonic crystal fiber is emulated by Rsoft software,combined with the analysis and research of the coupled mode theory simultaneously,the transmission spectrum of the filter is analyzed and verified.On this basis,the designed filter has been experimentally tested from polarization dependence and axial stress characteristics,and then a filter transmission spectrum with minimum insertion loss of 13 d B,extinction ratio greater than 8 d B and maximum strain linear sensitivity of 2.07 pm/?? is acquired.(2)Based on the proposed triple-core photonic crystal fiber filter,a stable,switchable and tunable MW-EDFL is obtained.By adjusting the polarization controller properly,the switchable lasing outputs among single-,dual-and triple-wavelength can be achieved.Meanwhile,the side mode suppression ratio(SMSR)is higher than 44 d B and 36 d B for single-,multi-wavelength lasing outputs,respectively.By changing the axial strain of the filter,the single-and dual-wavelength laser can be tuned with the tunable range of 9.28 nm,6.86 nm,respectively.And the maximal strain linear sensitivity of the laser regime is up to 2.41 pm/??.In addition,the laser in each state has good stability performance.The maximum wavelength shift value and power fluctuation value of multi-wavelength lasing outputs are less than 0.06 nm and 0.98 d B respectively in the two-hour stability test.(3)Based on cascading filter and multi-mode-triple-core photonic crystal fiber(MMF-TCPCF)filter which are two modified structural filters,two stable,switchable and tunable MW-EDFLs are obtained.The MW-EDFL based on cascading filter,has realized arbitrary switchable lasing outputs among single-,dual-and triple-wavelength.Meanwhile,the SMSR is higher than 45 d B and 35 d B for single-and multi-wavelength lasing outputs,respectively.Besides,the tunable single-,dual-and triple-wavelength laser can be obtained with the maximum tunable range of 13.38 nm,7.9 nm,4.48 nm,respectively.And the maximal axial strain linear sensitivity of the laser regime is up to 2.33 pm/??.All laser regimes obtained have good stability.The MW-EDFL based on MMF-TCPCF filter,has obtained the arbitrary switching of single-,dual-,triple-,quadand penta-wavelength laser regimes.Meanwhile,the SMSR is higher than 50 d B and 33 d B for single-and multi-wavelength lasing outputs,respectively.Furthermore,tunable single-,dual-and triple-wavelength regimes are also achieved with maximum tuning range of 19.6 nm,10.34 nm,6.84 nm,respectively.And the maximal strain linear sensitivity of the laser regime reaches to 2.19 pm/??.All laser regimes have proven good stability and good equalization characteristic.