Generation of 36  μm radiation and telecom-band amplification by four-wave mixing in a silicon waveguide with normal group velocity dispersion

Abstract

Received Month X, XXXX; revised Month X, XXXX; accepted Month X, XXXX; posted Month X, XXXX (Doc.ID XXXXX); published Month X, XXXX Mid-infrared light generation through four-wave mixing-based frequency down-conversion in a normal group velocity dispersion silicon waveguide is demonstrated. A telecom-wavelength signal is down-converted across more than 1.2 octaves using a pump at 2190 nm in a 1cm long waveguide. At the same time 13dB parametric gain of the telecom signal is obtained. OCIS Codes: (130.3120) Integrated optics devices; (190.0190) Nonlinear optics;The broadband transparency of the silicon-on-insulator waveguide platform from 1.1µm (limited by the absorption of silicon) to ~4µm (limited by the absorption of SiO2) [1] enables the realization of photonic integrated circuits outside the telecommunication band. Such circuits can be valuable for spectroscopic sensing applications, which leverage the strong rovibrational absorption lines of molecules in the mid-infrared wavelength spectrum -the so-called molecular fingerprint region [2]. While silicon provides an excellent platform for passive waveguiding in this 1.1 -4 µm wavelength range [1,3], the generation and detection of mid-infrared radiation is not straightforward. Recent research has been geared towards the integration of III-V semiconductor devices onto the silicon photonics platform to implement this functionality [4,5]. However, mid-infrared semiconductor photodetectors suffer from poor sensitivity at room temperature due to their narrow band gap, while semiconductor light sources only offer a limited gain bandwidth and hence a limited emission wavelength range. Efficient nonlinear optical effects on the silicon photonic platform, making use of the instantaneous thirdorder χ(3) nonlinear effect, can provide a solution to many of these challenges. Recent work has shown that fourwave mixing-based nonlinear optical functions including supercontinuum generation [6], optical parametric amplification [7,8] and wavelength conversion [7][8][9][10] can be integrated for mid-infrared light generation within compact silicon photonic integrated circuits. Moreover, silicon waveguides accomplishing bi-directional broadband spectral translation of optical signals between 1620 nm and 2440 nm in the mid-infrared [11], and between 1312 nm and 1884 nm in the short-wave infrared [12] have been demonstrated using four-wave mixing phase matched by anomalous dispersion. Such spectral translation technology can be applied to mid-infrared spectroscopic functions on a silicon photonic integrated circuit, by using advanced telecom-wavelength laser sources and high-sensitivity photodetectors. In this paper, we demonstrate that by using silicon waveguides with normal dispersion, the range of mid-infrared light generation and spectral translation can be extended to 3.6 µm wavelength, by frequency down-conversion across 1.2 octaves from the telecom band.The spectral translator waveguide used in this work is dispersion engineered specifically to allow for phase matching far ...

Mid-infrared integrated photonics on silicon: a perspective

“…As unstrained silicon and non-poled amorphous materials such as silicon nitride are structurally centrosymmetric and lack second-order nonlinear response (χ 2 ), FWM is the most commonly utilized parametric process in silicon photonics. Indeed, mid-IR light generation and amplification, up to 3.6-μm wavelength using both pulsed [94][95][96][97] and CW pump sources [98][99][100], capitalizing on first-order FWM in the SOI platform have been reported by several groups. Unlike SRS, FWM (as well as other parametric processes) mandates phase matching and judicious dispersion engineering of the nonlinear optical waveguide to maximize the gain bandwidth and conversion efficiency.…”

Characterization and modeling of microstructured chalcogenide fibers for efficient mid-infrared wavelength conversion

“…Silicon, showing reduced two photon absorption, large Kerr nonlinearity and high refractive index at 2 µm, is a potential candidate. Dispersion engineered silicon integrated waveguides with strong light confinement have been successfully employed to achieve optical parametric amplification [7,8], wavelength conversion [7][8][9][10][11], and bidirectional broadband spectral translation of optical signals [12].…”

Long-wavelength silicon photonic integrated circuits

“…Especially the generation of mid-infrared light based on four-wave mixing is of interest. In this context we have demonstrated the generation of 3.6 µm radiation based on a telecom signal wavelength and a 2.2 µm pump laser, showing that the high refractive index contrast in silicon-on-insulator waveguides does not only help in improving the efficiency of the nonlinear processes, it also allows for dispersion engineering of the silicon waveguide structure in order to reach phase matching over such a wide wavelength span [11]. Supercontinuum generation using short pulse pump sources in the 1.9-2.3 µm wavelength range has also been demonstrated, as will be elaborated on during the conference [12][13].…”