On-Chip Mid-Infrared Supercontinuum Generation from 3 to 13 μm Wavelength

Abstract

Midinfrared spectroscopy is a universal way to identify chemical and biological substances. Indeed, when interacting with a light beam, most molecules are responsible for absorption at specific wavelengths in the mid-IR spectrum, allowing to detect and quantify small traces of substances. On-chip broadband light sources in the mid-infrared are thus of significant interest for compact sensing devices. In that regard, supercontinuum generation offers a mean to efficiently perform coherent light conversion over an ultrawide spectral range, in a single and compact device. This work reports the experimental demonstration of on-chip two-octave supercontinuum generation in the mid-infrared wavelength, ranging from 3 to 13 μm (that is larger than 2500 cm –1 ) and covering almost the full transparency window of germanium. Such an ultrawide spectrum is achieved thanks to the unique features of Ge-rich graded SiGe waveguides, which allow second-order dispersion tailoring and low propagation losses over a wide wavelength range. The influence of the pump wavelength and power on the supercontinuum spectra has been studied. A good agreement between the numerical simulations and the experimental results is reported. Furthermore, a very high coherence is predicted in the entire spectrum. These results pave the way for wideband, coherent, and compact mid-infrared light sources by using a single device and compatible with large-scale fabrication processes.

Far-IR to deep-UV adaptive supercontinuum generation using semiconductor nano-antennas via carrier injection rate modulation

“…The root of supercontinuum generation via an excitation wave is the second harmonic generation (SHG) process (Montesinos-Ballester et al 2020;Hilligsøe et al 2004).…”

“…In this study, semiconductor nano-antennas are proposed as energy-storing nanostructures that can generate an ultra-wideband supercontinuum ranging from the far-infrared range to the ultraviolet range of the spectrum and attain a supercontinuum-bandwidth that even surpasses the supercontinuum-bandwidth that is attained via optical fibers. Such a structure is simpler than the previously proposed micro-and nanoscale structures (Chen et al 2018;Monticone et al 2017;Hanke et al 2009;Ünlü et al 2011;Montesinos-Ballester et al 2020;Sain et al 2019), easier to fabricate (Sain et al 2019), and achieves a wider bandwidth than the previously reported bandwidths (Chen et al 2018;Husakou and Herrmann 2002;Mühlschlegel et al 2005;Liu et al 2015;Krasavin et al 2016;Gorbach 2015;Wu et al 2013;Dasgupta et al 2018;Park et al 2018;Horiuchi 2020;Bharadwaj et al 2011;Park 2009;Kullock et al 2018;Monticone et al 2017;Hanke et al 2009;Ünlü et al 2011;Montesinos-Ballester et al 2020), paving the way for on-chip spectroscopy, ultrashort pulse generation, and on-chip highenergy density storage. The paper also discusses the potential replacement of photonic crystal fibers with semiconductor nano-antennas for supercontinuum generation, provided that a certain pattern of optical excitation is followed.…”

Recent Advances in Supercontinuum Generation in Specialty Fiber

“…Advances in micro-fabrication technology have led to the demonstration of SC generation in a number of PIC platforms, including SC covering the entire MIR first in a chalcogenide chip, and then in a silicon-germanium system. The germanium-based platforms are particularly attractive due to their CMOS compatibility, their wide transmission window in the MIR and their large nonlinearities, enabling SC generation up to 13 µm [158,159].…”

Mid-infrared Octave-spanning Supercontinuum Generation in an All-normal Dispersion SiGe Waveguide

“…In this context, we aim to achieve a small footprint low-cost sensing platform with an integrated supercontinuum (SC) source to overcome these limits. Great efforts have been devoted to demonstrating octave-spanning SCs in mid-IR up to 8.5 μm [3] and recently up to 13 μm [4] in dispersion engineered SiGe-based waveguides. Furthermore, we performed dispersion trimming, hence altering the SC properties, in a post-fabrication step [5], and we reported high coherence of an SC at frequencies separated by an octave [6].…”