A dual-core photonic crystal fiber coupler based on the heavily ${\rm GeO}_2$-doped-silica-air cladding and composite-liquid (${\rm CS}_2$ and ${\rm C}_2{\rm Cl}_4$) core is proposed to obtain the saturable absorber (SA). It is demonstrated by numerical simulations that the SA with appropriate parameters can exhibit the normal dispersion, high nonlinearity, and flat profile of the linear coupling lengths in the wavelength range from 1500 to 2000 nm. The input pulses with durations ${\gt} 2 \;{\rm ps}$ exhibit relatively high transmissions and low saturable powers mainly because of the strong effect of stimulated Raman scattering in the SA. Consequently, the SA with the ${\rm GeO}_2$ concentration ratio of 80 mol% can be employed in both the erbium- and thulium-doped fiber mode-locked lasers with all-normal or large net-normal dispersion. The dissipative soliton pulses with tunable wavelengths can be obtained in both cases.

中文翻译：

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基于宽带复合充液双芯光子晶体光纤耦合器的饱和吸收器

基于重掺杂$ {\ rm GeO} _2 $的石英空气包层和复合液体（$ {\ rm CS} _2 $和$ {\ rm C} _2 {\建议使用rm Cl} _4 $）磁芯来获得可饱和吸收器（SA）。通过数值模拟表明，具有适当参数的SA可以在1500至2000 nm波长范围内表现出正常的色散，高的非线性和线性耦合长度的平坦分布。持续时间为{{\ gt} 2 \; {\ rm ps} $的输入脉冲表现出较高的透射率和较低的饱和功率，这主要是由于SA中受激拉曼散射的强烈影响。因此，具有$ {\ rm GeO} _2 $的SA在具有全法向色散或大法向净色散的掺-和掺fiber光纤锁模激光器中，都可以采用80 mol％的浓度比。在这两种情况下都可以获得具有可调波长的耗散孤子脉冲。