All-fiber theta cavity multi-wavelength Tm-doped fiber laser based on a dual biconical taper filter

• Published in: Optical fiber technology Vol. 60; p. 102331
• Main Authors: Wu, Xiangnong, Miao, Junyu, Wang, Ying, Chen, Weijuan, Chen, Zhihao
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 01.12.2020
• Subjects: Biconical taper filter; Isolator-free; Multi-wavelength; Theta cavity; Tm-doped fiber laser; Isolator-free; Tm-doped fiber laser; Multi-wavelength; Biconical taper filter; Theta cavity
• ISSN: 1068-5200; 1095-9912
• DOI: 10.1016/j.yofte.2020.102331

We report experimentally a multi-wavelength Thulium-doped fiber (TDF) laser based on all-fiber theta cavity and a dual biconical taper filter without isolator. The dual biconical taper with waist of 50 μm and length of 188.05 mm is implemented as a narrow band filter. Three stable laser output states are successfully obtained with one, two or three wavelengths by increasing the pump power and properly adjusting the polarization controller. For single-wavelength output at 1978.80 nm, the full width at half maximum (FWHM) is 0.23 nm with optical signal-to-noise ratios (OSNRs) larger than 19 dB. For dual-wavelength output at 1978.80 nm and 1991.80 nm, the FWHMs are 0.24 nm and 0.19 nm with OSNRs of 30 dB and 19 dB, respectively. For triple-wavelength operation at 1978.8 nm, 1990.80 nm and 1991.60 nm, the FWHMs are 0.2 ~ 0.26 nm and OSNRs of 27 dB, 20 dB and 22 dB, respectively. The stable multiple wavelengths laser emission output with maximal (minimal) interval of 13 nm (1 nm) is achieved at 2 μm region. There is negligible wavelength shift for over one hour. It can be verified that this scheme using a dual biconical fiber taper filter is feasible and can be an alternative solution for all-fiberized stable narrow-bandwidth multi-wavelength TDF laser.