Bridging the mid-infrared-to-telecom gap with silicon nanophotonic spectral translation

• Published in: Nature photonics Vol. 6; no. 10; pp. 667 - 671
• Main Authors: Liu, Xiaoping, Kuyken, Bart, Roelkens, Gunther, Baets, Roel, Osgood, Richard M., Green, William M. J.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.10.2012; Nature Publishing Group
• Subjects: 639/624/1075/1082; 639/624/1075/187; 639/624/399/1099; 639/624/400/385; Applied and Technical Physics; Environmental monitoring; letter; Nanocomposites; Nanomaterials; Nanostructure; Physics; Physics and Astronomy; Quantum Physics; Semiconductors; Silicon; Spectra; Telecommunications; Translations; Wavelengths
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/nphoton.2012.221

Extending beyond traditional telecom-band applications to optical interconnects 1 , the silicon nanophotonic integrated circuit platform also has notable advantages for use in high-performance mid-infrared optical systems operating in the 2–8 µm spectral range 2 , 3 . Such systems could find applications in industrial and environmental monitoring 4 , threat detection 5 , medical diagnostics 6 and free-space communication 7 . Nevertheless, the advancement of chip-scale systems is impeded by the narrow-bandgap semiconductors traditionally used to detect mid-infrared photons. The cryogenic or multistage thermo-electric cooling required to suppress dark-current noise 8 , which is exponentially dependent on E g / kT , can restrict the development of compact, low-power integrated mid-infrared systems. However, if the mid-infrared signals were spectrally translated to shorter wavelengths, wide-bandgap photodetectors could be used to eliminate prohibitive cooling requirements. Furthermore, such detectors typically have larger detectivity and bandwidth than their mid-infrared counterparts 8 . Here, we use efficient four-wave mixing in silicon nanophotonic wires 9 , 10 , 11 , 12 to facilitate spectral translation of a signal at 2,440 nm to the telecom band at 1,620 nm, across a span of 62 THz. Furthermore, a simultaneous parametric translation gain of 19 dB can significantly boost sensitivity to weak mid-infrared signals. Efficient four-wave-mixing process in silicon nanophotonic wires facilitates spectral translation of a signal at 2,440 nm to the telecommunications band at 1,620 nm across a span of 62 THz. This approach helps eliminate cooling requirements for the narrow-bandgap semiconductors traditionally used to detect mid-infrared photons.