We report the observation of second order Bragg resonance[2nd-OBG]produced by tilted fiber gratings[TFGs]fabricated using phase mask UV inscription.The theoretical analysis has revealed that the generation of high order Bragg resonance of gratings is induced by a square-shape refractive index profile,which is caused by over-saturated UV exposure.In the experiment,we have studied the TFGs with different tilt angles under over-saturated UV exposure,in which all gratings have showed the 2nd-OBR,and the larger tilt angle of the grating has the stronger 2nd-OBR.When the tilt angle of the grating is ～45°,the Bragg resonance exhibits very strong polarization dependence,because the 2nd-OBR wave-length is located within the polarizing bandwidth of 45° TFG.Finally,we have demonstrated an erbium-doped fiber laser with ＞ 99.9％ degree of polarization,and,by applying mechanical stretching on the grating,a wavelength tunable laser output has been achieved.The output laser shows ～0.2 dB amplitude variation within 1 h continuous monitoring of the laser.

Qingguo Song;Bolin Ye;Xiangpeng Xiao;Chengjun Huang;Chengbo Mou;Zhijun Yan;Lin Zhang

School of Optical and Electronic Information,NGIA,Huazhong University of Science and Technology,Wuhan 430074,China;Shenzhen Techwinsemi Optoelectronic Co.,Ltd.,Shenzhen 518000,China;Key Laboratory of Specialty Fiber Optics and Optical Access Networks,Shanghai Institute for Advanced Communication and Data Science,Joint International Research Laboratory of Specialty Fiber Optics and Advanced Communication,Shanghai University,Shanghai 200444,China;Aston Institute of Photonic Technologies,Aston University,Birmingham B47ET,UK

中国光学快报（英文版）

[1]Qingguo Song;Bolin Ye;Xiangpeng Xiao;Chengjun Huang;Chengbo Mou;Zhijun Yan;Lin Zhang-.Theoretical and experimental analysis of second order Bragg resonance of 45° TFG and its fiber laser application)[J].中国光学快报（英文版）,2022(01):122-126

OBG,OBR

Theoretical,experimental,analysis,second,order,Bragg,resonance,fiber,laser,application,We,report,observation,2nd,produced,by,tilted,gratings,TFGs,fabricated,using,phase,mask,UV,inscription,theoretical,revealed,that,generation,high,induced,square,shape,refractive,profile,which,caused,over,saturated,exposure,In,have,studied,different,angles,under,showed,larger,stronger,When,exhibits,very,polarization,dependence,because,located,within,polarizing,bandwidth,Finally,demonstrated,erbium,doped,degree,applying,mechanical,stretching,wavelength,tunable,output,been,achieved,shows,dB,amplitude,variation,continuous,monitoring

0.47458