Wideband Ge-Rich SiGe Polarization-Insensitive Waveguides for Mid-Infrared Free-Space Communications
AbstractThe recent development of quantum cascade lasers, with room-temperature emission in the mid-infrared range, opened new opportunities for the implementation of ultra-wideband communication systems. Specifically, the mid-infrared atmospheric transparency windows, comprising wavelengths between 3–5 µm and 8–14 µm, have great potential for free-space communications, as they provide a wide unregulated spectrum with low Mie and Rayleigh scattering and reduced background noise. Despite the great efforts devoted to the development of mid-infrared sources and detectors, little attention is dedicated to the management of polarization for signal processing. In this work, we used Ge-rich SiGe alloys to build a wideband and polarization-insensitive mid-infrared photonic platform. We showed that the gradual index change in the SiGe alloys enabled the design of waveguides with remarkably low birefringence, below 2 × 10−4, over ultra-wide wavelength ranges within both atmospheric transparency windows, near wavelengths of 3.5 µm and 9 µm. We also report on the design of a polarization-independent multimode interference device achieving efficient power splitting in an unprecedented 4.5-µm bandwidth at around 10-µm wavelength. The ultra-wideband polarization-insensitive building blocks presented here pave the way for the development of high-performance on-chip photonic circuits for next-generation mid-infrared free-space communication systems. View Full-Text
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Vakarin, V.; Ramírez, J.M.; Frigerio, J.; Liu, Q.; Ballabio, A.; Le Roux, X.; Alonso-Ramos, C.; Isella, G.; Cheben, P.; N. Ye, W.; Vivien, L.; Marris-Morini, D. Wideband Ge-Rich SiGe Polarization-Insensitive Waveguides for Mid-Infrared Free-Space Communications. Appl. Sci. 2018, 8, 1154.
Vakarin V, Ramírez JM, Frigerio J, Liu Q, Ballabio A, Le Roux X, Alonso-Ramos C, Isella G, Cheben P, N. Ye W, Vivien L, Marris-Morini D. Wideband Ge-Rich SiGe Polarization-Insensitive Waveguides for Mid-Infrared Free-Space Communications. Applied Sciences. 2018; 8(7):1154.Chicago/Turabian Style
Vakarin, Vladyslav; Ramírez, Joan M.; Frigerio, Jacopo; Liu, Qiankun; Ballabio, Andrea; Le Roux, Xavier; Alonso-Ramos, Carlos; Isella, Giovanni; Cheben, Pavel; N. Ye, Winnie; Vivien, Laurent; Marris-Morini, Delphine. 2018. "Wideband Ge-Rich SiGe Polarization-Insensitive Waveguides for Mid-Infrared Free-Space Communications." Appl. Sci. 8, no. 7: 1154.
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