Abstract
Silicon (Si), tin (Sn), and germanium (Ge) alloys have attracted research attention as direct band gap semiconductors with applications in electronics and optoelectronics. In particular, GeSn field effect transistors can exhibit very high performance in terms of power reduction and operating speed because of the high electron drift mobility, while the SiGeSn system can be constructed using CMOS-compatible techniques to realize lasers, LED, and photodetectors. The wide Si, Ge and Sn transparencies allow the use of binary and ternary alloys extended to mid-IR wavelengths, where nonlinearities can also be employed. However, neither theoretical or experimental predictions of nonlinear features in SiGeSn alloys are reported in the literature. For the first time, a rigorous and detailed physical investigation is presented to estimate the two photon absorption (TPA) coefficient and the Kerr refractive index for the SiGeSn alloy up to 12 μm. The TPA spectrum, the effective TPA wavelength cut-off, and the Kerr nonlinear refractive index have been determined as a function of alloy compositions. The promising results achieved can pave the way to the demonstration of on-chip nonlinear-based applications, including mid-IR spectrometer-on-a-chip, all-optical wavelength down/up-conversion, frequency comb generation, quantum-correlated photon-pair source generation and supercontinuum source creation, as well as Raman lasing.
Highlights
Space for heterostructures in order to realize QWs based on strain-free pairs of Ge1−x−ySixSny alloys, one of which would act as a QW and the other as the barrier material
A mathematical modeling based on a physical approach has been implemented for investigating the spectrum of the two photon absorption induced by direct and indirect transitions in the unstrained Ge1−x−ySixSny alloy
The Ge testing analysis has been used as a starting point for the estimation of the two-photon absorption (TPA) processes in the Ge1−x−ySixSny ternary alloy
Summary
Space for heterostructures in order to realize QWs based on strain-free (lattice-matched) pairs of Ge1−x−ySixSny alloys, one of which would act as a QW and the other as the barrier material. In this sense, Ge1−x−ySixSny MQW lasing has been assumed as feasible within the wavelength range of 2.2–6.0 μm. Looking beyond midwave, there are a number of longwave, and far infrared opportunities for using the Ge1−x−ySixSny alloy in order to realize intersubband quantum cascade lasers (QCL). The nonlinear photonics based on the ternary alloy Ge1−x−ySixSny is still an open issue. The only caveat is the presence of two-photon absorption (TPA), which is going to be stronger in the Ge1−x−ySixSny ternary than in silicon material
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