Search

Air pollution is one of the largest risk factors for disease or premature death globally, yet current portable monitoring technology cannot provide adequate protection at a local community level. Within the TRIAGE project, a smart, compact and cost-effective air quality sensor network will be developed for the hyperspectral detection of gases which are relevant for atmospheric pollution monitoring or dangerous for human health. The sensor is based on a mid-infrared supercontinuum source, providing ultra-bright emission across the 2-10 mu m wavelength region. Within this spectral range, harmful gaseous species can be detected with high sensitivity and selectivity. The spectroscopic sensor, which includes a novel multi-pass cell and detector, enables a smart robust photonic sensing system for real-time detection. With built-in chemometric analysis and cloud connection, the sensor will feed advanced deep-learning algorithms for various analyses, ranging from long-term continental trends in air pollution to urgent local warnings and alerts. Community-based distributed pollution sensing tests will be verified on municipal building rooftops and local transport platforms., Funding Agencies|Horizon 2020 [101015825, 732968]; European Unions Framework Programme for Research and Innovation

Contains fulltext : 244879.pdf (Publisher’s version ) (Open Access)

We report an octave-spanning coherent supercontinuum (SC) fiber laser with excellent noise and polarization properties. This was achieved by pumping a highly birefringent all-normal dispersion photonic crystal fiber with a compact high-power ytterbium femtosecond laser at 1049 nm. This system generates an ultra-flat SC spectrum from 670 to 1390 nm with a power spectral density higher than 0.4 mW/nm and a polarization extinction ratio of 17 dB across the entire bandwidth. An average pulse-to-pulse relative intensity noise down to 0.54% from700 to 1100nmwas measured and found to be in good agreement with numerical simulations. This highly stable broadband source could find strong potential applications in biomedical imaging and spectroscopy where an improved signal-to-noise ratio is essential.

Air pollution is one of the largest risk factors for disease or premature death globally, yet current portable monitoring technology cannot provide adequate protection at a local community level. Within the TRIAGE project, a smart, compact and cost-effective air quality sensor network will be developed for the hyperspectral detection of gases which are relevant for atmospheric pollution monitoring or dangerous for human health. The sensor is based on a mid-infrared supercontinuum source, providing ultra-bright emission across the 2 10 um wavelength region. Within this spectral range, harmful gaseous species can be detected with high sensitivity and selectivity. The spectroscopic sensor, which includes a novel multi-pass cell and detector, enables a smart robust photonic sensing system for real-Time detection. With built-in chemometric analysis and cloud connection, the sensor will feed advanced deep-learning algorithms for various analyses, ranging from long-Term continental trends in air pollution to urgent local warnings and alerts. Community-based distributed pollution sensing tests will be verified on municipal building rooftops and local transport platforms.

A pure silica photonic crystal fiber with a group velocity dispersion (β2) of 4 ps2/km at 1.55 μm and less than 7 ps2/km from 1.32 μm to the zero dispersion wavelength (ZDW) 1.80 μm was designed and fabricated. The dispersion of the fiber was measured experimentally and found to agree with the fiber design, which also provides low loss below 1.83 μm due to eight outer rings with increased hole diameters. The fiber was pumped with a 1.55 μm, 125 fs laser and, at the maximum in-coupled peak power (P0) of 9 kW, a 1.34-1.82 μm low-noise spectrum with a relative intensity noise below 2.2% was measured. The numerical modeling agreed very well with the experiments and showed that P0 could be increased to 26 kW before noise from solitons above the ZDW started to influence the spectrum by pushing high-noise dispersive waves through the spectrum.

13 augustus 2019, Contains fulltext : 214817.pdf (publisher's version ) (Open Access)

We demonstrate surprising effects of technical pump laser fluctuations on the noise of a normal-dispersion fs-pumped supercontinuum and how the noise varies with power in fibers with a zero-dispersion at longer wavelengths.

One of the requirements for generating a low noise supercontinuum (SC) in a normal dispersion fiber using a femtosecond (fs) pump is to have the minimum absolute dispersion wavelength to be close to zero in order to avoid parametric Raman noise [1]. SC generation in all-normal dispersion fibers can under certain requirements provide a highly coherent spectrum [2, 3], which is of key importance to a large range of imaging and spectroscopy applications. Key requirements to avoid Raman noise and noise from polarization mode instability (PMI) is to have a sufficiently low peak power (P0), short pulse length (T0), short fiber length, and high fiber birefringence [4].

We demonstrate a 70 mol % GeO2 doped fiber for mid-infrared supercontinuum generation. Experiments ensure a highest output power for a broadest spectrum from 1000nm to 3000nm from this fiber, while being pumped by a broadband 4 stage Erbium fiber based MOPA. Our investigations reveal the unexploited potential of Germania doped fiber for mid-infrared supercontinuum generation. To the best of our knowledge, this is the record power, for an ultrabroadband, all-fiberized, and compact device size supercontinuum light source based on Silica and Germania fiber, ever demonstrated to the date.

In this paper, a versatile method for synchronized imaging upconversion in the mid-IR wavelength range is presented. A 1064 nm master oscillator power amplifier source pump laser is electronically adjusted in pulse duration and repetition rate to match the output from a 40 kHz, 1.6 ns pulse mid-IR supercontinuum light source followed by upconversion to the near-infrared captured by a sensitive CCD camera. The systems noise is characterized, and we present a simple algorithm for correcting for the image distortion caused by the use of off-axis parabolic mirrors.