Ramirez J M, Vakarin V, Frigerio J, Chaisakul P, Chrastina D, Le Roux X, Ballabio A, Vivien L, Isella G, Marris-Morini D
Opt Express. 2017 Mar 20;25(6):6561-6567. doi: 10.1364/OE.25.006561.
This work explores the use of Ge-rich graded-index SixGex rib waveguides as building blocks to develop integrated nonlinear optical devices for broadband operation in the mid-IR. The vertical Ge gradient concentration in the waveguide core renders unique properties to the guided optical mode, providing tight mode confinement over a broadband mid-IR wavelength range from λ = 3 µm to 8 µm. Additionally, the gradual vertical confinement pulls the optical mode upwards in the waveguide core, overlapping with the Ge-rich area where the nonlinear refractive index is larger. Moreover, the Ge-rich graded-index SixGex waveguides allow efficient tailoring of the chromatic dispersion curves, achieving flat anomalous dispersion for the quasi-TM optical mode with D ≤ 14 ps/nm/km over a ~1.4 octave span while retaining an optimum third-order nonlinear parameter, γeff. These results confirm the potential of Ge-rich graded-index SixGex waveguides as an attractive platform to develop mid-IR nonlinear approaches requiring broadband dispersion engineering.
这项工作探索了使用富锗渐变折射率SixGex肋形波导作为构建模块，来开发用于中红外宽带操作的集成非线性光学器件。波导芯中的垂直锗梯度浓度赋予了导光模式独特的特性，在从λ = 3 µm到8 µm的宽带中红外波长范围内提供了紧密的模式限制。此外，逐渐增加的垂直限制将光模式向上拉到波导芯中，与非线性折射率较大的富锗区域重叠。而且，富锗渐变折射率SixGex波导允许有效地调整色散曲线，在约1.4倍频程跨度内为准TM光模式实现平坦的反常色散，D≤14 ps/nm/km，同时保留最佳的三阶非线性参数γeff。这些结果证实了富锗渐变折射率SixGex波导作为一个有吸引力的平台来开发需要宽带色散工程的中红外非线性方法的潜力。
