采用复合滤波器的温度可调谐多波长光纤激光器

提出了一种基于复合光纤滤波器的在室温下稳定输出多波长掺铒光纤激光器，该激光器由两个级联球状结构的马赫-增德尔干涉仪（MZI）和一个双折射光纤滤波器-Lyot滤波器组成。球状结构MZI是由光纤熔接机在一段单模光纤（SMF）放电设计而成的。Lyot双折射光纤滤波器是利用一段保偏光纤（PMF）和两个偏振控制器（PC）连接而成，该结构可以诱导非线性偏振旋转效应和双折射光纤效应来抑制模式竞争产生多波长。Lyot滤波器和球状结构的MZI作为模式限制器件，并且Lyot滤波器对级联球状结构MZI的透射谱进行调制，其透射谱周期决定了复合滤波器结构的透射谱周期。在室温下，该系统实现了边模抑制比约为40 dB的九个波长的同时激射，且波长间隔约为0.68 nm，与Lyot滤波器透射谱周期一致。为了验证输出波长的稳定性，在2 h内，每隔10 min观察输出的波长，实验证明，室温下中心波长输出功率的浮动小于0.67 dB。此外，将两个球状结构MZI放置在高温炉上，使其外界温度从30℃升至110℃时，输出波长光谱的调谐范围可达到6.69 nm。

Temperature tunable multiwavelength fiber laser by using compounded filter

A stable multiwavelength erbium-doped fiber laser was proposed and experimentally demonstrated by using a compounded fiber filter, which was composed of a Mach-Zehnder interferometer(MZI) and a birefringence fiber filter-Lyot filter. The MZI was fabricated by using the fiber fusion splicer to splice a section of SMF to form two cascaded spherical structures. The Lyot filter was incorporating a segment of polarization maintaining fiber(PMF) and two polarization controllers(PCs), which provided nonlinear polarization rotation(NPR) and birefringent filter effect to suppress the mode competition and generate multiwavelength. Using cascaded spherical-shape structures MZI and the Lyot filter as mode restricting elements respectively, the transmission spectrum of cascaded spherical-shape structures MZI was modulated by the Lyot filter, which determined the period of the compounded structure. In the experiments, 9-wavelength operation with a side-mode suppression ratio (SMSR) of~40 dB was achieved, and the space of wavelength was 0.68 nm defined by the Lyot filter. When the stability of proposed structure was observed for 2 hours every 10 minutes, the fluctuation of the central wavelength's output power was less than 0.67 dB. Furthermore, when the two spherical-shape structures MZI was fixed on a furnace and the temperature varied from 30℃ to 110℃, the spectrum of output wavelength can be tuned within the range of 6.69 nm.