Recent advances in supercontinuum generation in specialty optical fibers [Invited]

Abstract

The physics and applications of fiber-based supercontinuum (SC) sources have been a subject of intense interest over the last decade, with significant impact on both basic science and industry. New uses for SC sources are also constantly emerging due to their unique properties that combine high brightness, multi-octave frequency bandwidth, fiber delivery and single-mode output. The last few years have seen significant research efforts focused on extending the wavelength coverage of SC sources towards the 2 to 20 µm molecular fingerprint mid-infrared (MIR) region and in the ultraviolet (UV) down to 100 nm, while also improving stability, noise and coherence, output power and polarization properties. Here we review a selection of recent advances in SC generation in a range of specialty optical fibers including: fluoride, chalcogenide, telluride, and silicon-core fibers for the MIR; UV-grade silica fibers and gas-filled hollow-core fibers for the UV range; and all-normal dispersion fibers for ultra-low noise coherent SC generation.

Mid-infrared supercontinuum-based Fourier transform spectroscopy for plasma analysis

“…Currently, the relative intensity noise of the MIR SC source limits the sensitivity of the spectrometer, although this is not essential for the demonstrated application, in identification and quantification of the products of a plasma reaction. Moreover, with the current rapid developments in MIR SC sources, it is anticipated that the intensity noise of these sources will be reduced further in the near future 29 , 34 . Finally, the spatial coherence of the MIR SC beam could also be exploited for other applications, such as for accurate in-situ probing in plasmas, to monitor the plasma dynamics, as well as to detect intermediate products in the plasma.…”

“…SC sources have demonstrated powerful capabilities in emitting in the visible and near-infrared range using silica fibers. Sources emitting up to 4 μm using fluoride fibers have become commercially available in recent years 29 . Several applications for these type of SC sources have been demonstrated, such as absorption spectroscopy with high sensitivity and selectivity for simultaneous measurement of multiple compounds 30 , spectroscopic standoff detection 31 , or optical coherence tomography in the MIR range providing real-time and high-resolution images 32 , 33 .…”

Mid-infrared Supercontinuum-based Fourier Transform Spectroscopy for plasma analysis

“…In conclusion, the reaction products were quanti ed for a discharge plasma with a varying ratio of CO Currently, the relative intensity noise of the MIR SC source limits the sensitivity of the spectrometer, although this is not essential for the demonstrated application, in identi cation and quanti cation of the products of a plasma reaction. Moreover, with the current rapid developments in MIR SC sources, it is anticipated that the intensity noise of these sources will be reduced further in the near future 29,32 . Finally, the spatial coherence of the MIR SC beam could also be exploited for other applications, such as for accurate in-situ probing in plasmas, to monitor the plasma dynamics, as well as to detect intermediate products in the plasma.…”

“…Sources emitting up to 4 μm using uoride bers have become commercially available in recent years 29 .…”

Non-spectroscopic sensing enabled by electro-optical reservoir computer

“…where, D 𝑚 ( 𝑓 ) defines the spectral response of the photodetector at channel 𝑚 of the sensor. For demonstration purposes, the sensor is assumed to be equipped with a broadband light source with a top-hat spectral power density S in profile from 3.1 to 3.7 𝜇m in wavelength that is normalised, i.e., ∫ S in ( 𝑓 )d 𝑓 = 1 W. For practical realisations, photo-luminescent emission from rare earth doped optical fibre [34] or a supercontinuum light-source [35,36] can be used. Figure 8(a) shows the pseudo-colouring of the biomimetic sensor output P(𝑛) = [𝑃 1 ; 𝑃 2 ; 𝑃 3 ] T following the Red-Green-Blue (RGB) colour scheme.…”