Abstract 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.

中文翻译：

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基于双双锥滤光片的全光纤θ腔多波长掺铥光纤激光器

摘要 我们实验性地报告了一种基于全光纤θ腔和没有隔离器的双双锥形锥形滤波器的多波长掺铥光纤 (TDF) 激光器。腰部为 50 μm 和长度为 188.05 mm 的双双锥被实现为窄带滤波器。通过增加泵浦功率和适当调整偏振控制器，成功地获得了一种、两种或三种波长的三种稳定的激光输出状态。对于 1978.80 nm 的单波长输出，半高宽 (FWHM) 为 0.23 nm，光信噪比 (OSNR) 大于 19 dB。对于 1978.80 nm 和 1991.80 nm 的双波长输出，FWHM 分别为 0.24 nm 和 0.19 nm，OSNR 分别为 30 dB 和 19 dB。对于 1978.8 nm、1990.80 nm 和 1991.60 nm 的三波长操作，FWHM 为 0.2 ~ 0。26 nm 和 OSNR 分别为 27 dB、20 dB 和 22 dB。在 2 μm 区域实现了最大（最小）间隔为 13 nm (1 nm) 的稳定多波长激光发射输出。超过一小时的波长偏移可以忽略不计。可以验证，这种采用双双锥光纤锥形滤波器的方案是可行的，可以作为全光纤稳定窄带多波长TDF激光器的替代方案。