Wavelength conversion at 10 Gb/s by four-wave mixing over a 30-nm interval

We show that the use of a long semiconductor optical amplifier increases the error-free conversion interval of a four-wave mixing (FWM)-based wavelength converter. 30-nm wavelength down-conversion and 15-nm up-conversion have been obtained at 10 Gb/s. This result is a significant improvement over the previous best performance of a FWM-based wavelength converter and suggests that the full erbium-doped fiber amplifier bandwidth can be covered with FWM wavelength converters

30-nm wavelength conversion at 10 Gbit/s by four-wave mixing in a semiconductor optical amplifier

Four-wave mixing (FWM) in semiconductor optical amplifiers (SOAs) is currently the only available strictly transparent wavelength-conversion technique, which is not penalized by phase matching. The span of the conversion is limited primarily by conversion efficiency and signal-to-noise (SNR) issues, both of which are expected to improve with the use of longer SOAs. In this paper, we demonstrate significantly enhanced performance of long converters in a system experiment at 10 Gbit/s. The experiment shows for the first time, to our knowledge, that FWM wavelength down-conversions can span the full gain bandwidth of erbium-doped fiber amplifiers

Development of Lumped Element Kinetic Inductance Detectors for the W-Band

We are developing a Lumped Element Kinetic Inductance Detector (LEKID) array able to operate in the W-band (75-110 GHz) in order to perform ground-based Cosmic Microwave Background (CMB) and mm-wave astronomical observations. The W-band is close to optimal in terms of contamination of the CMB from Galactic synchrotron, free-free, and thermal interstellar dust. In this band, the atmosphere has very good transparency, allowing interesting ground-based observations with large (>30 m) telescopes, achieving high angular resolution (<0.4 arcmin). In this work we describe the startup measurements devoted to the optimization of a W-band camera/spectrometer prototype for large aperture telescopes like the 64 m SRT (Sardinia Radio Telescope). In the process of selecting the best superconducting film for the LEKID, we characterized a 40 nm thick Aluminum 2-pixel array. We measured the minimum frequency able to break CPs (i.e. $h\nu=2\Delta\left(T_{c}\right)=3.5k_{B}T_{c}$) obtaining $\nu=95.5$ GHz, that corresponds to a critical temperature of 1.31 K. This is not suitable to cover the entire W-band. For an 80 nm layer the minimum frequency decreases to 93.2 GHz, which corresponds to a critical temperature of 1.28 K; this value is still suboptimal for W-band operation. Further increase of the Al film thickness results in bad performance of the detector. We have thus considered a Titanium-Aluminum bi-layer (10 nm thick Ti + 25 nm thick Al, already tested in other laboratories), for which we measured a critical temperature of 820 mK and a cut-on frequency of 65 GHz: so this solution allows operation in the entire W-band.Comment: 16th International Workshop on Low Temperature Detectors, Grenoble 20-24 July 2015, Journal of Low Temperature Physics, Accepte

Selective laser melting process of Al–based pyramidal horns for the w-band: fabrication and testing

In the context of exploring the possibility of using Al-powder Selective Laser Meltingto fabricate horn antennas for astronomical applications at millimeter wavelengths,we describe the design, the fabrication, the mechanical characterization, and theelectromagnetic performance of additive manufactured horn antennas for the W-band. Our aim, in particular, is to evaluate the performance impact of two basickinds of surface post-processing (manual grinding and sand-blasting) to deal withthe well-known issue of high surface roughness in 3D printed devices. We performedcomparative tests of co-polar and cross-polar angular response across the whole W-band, assuming a commercially available rectangular horn antenna as a reference.Based on gain and directivity measurements of the manufactured samples, we finddecibel-level detectable deviations from the behavior of the reference horn antenna,and marginal evidence of performance degradation at the top edge of the W-band.We conclude that both kinds of post-processing allow achieving good performancefor the W-band, but the higher reliability and uniformity of the sand-blasting post-process encourage exploring similar techniques for further development of aluminumdevices at these frequencies

Stable mode-locked pulses from mid-infrared semiconductor lasers

We report the unequivocal demonstration of mid-infrared mode-locked pulses from a semiconductor laser. The train of short pulses was generated by actively modulating the current and hence the optical gain in a small section of an edge-emitting quantum cascade laser (QCL). Pulses with pulse duration at full-width-at-half-maximum of about 3 ps and energy of 0.5 pJ were characterized using a second-order interferometric autocorrelation technique based on a nonlinear quantum well infrared photodetector. The mode-locking dynamics in the QCLs was modelled and simulated based on Maxwell-Bloch equations in an open two-level system. We anticipate our results to be a significant step toward a compact, electrically-pumped source generating ultrashort light pulses in the mid-infrared and terahertz spectral ranges.Comment: 26 pages, 4 figure

Kinetic Inductance Detectors for the OLIMPO experiment: design and pre-flight characterization

We designed, fabricated, and characterized four arrays of horn--coupled, lumped element kinetic inductance detectors (LEKIDs), optimized to work in the spectral bands of the balloon-borne OLIMPO experiment. OLIMPO is a 2.6 m aperture telescope, aimed at spectroscopic measurements of the Sunyaev-Zel'dovich (SZ) effect. OLIMPO will also validate the LEKID technology in a representative space environment. The corrected focal plane is filled with diffraction limited horn-coupled KID arrays, with 19, 37, 23, 41 active pixels respectively at 150, 250, 350, and 460$\:$GHz. Here we report on the full electrical and optical characterization performed on these detector arrays before the flight. In a dark laboratory cryostat, we measured the resonator electrical parameters, such as the quality factors and the electrical responsivities, at a base temperature of 300$\:$mK. The measured average resonator $Q$s are 1.7$\times{10^4}$, 7.0$\times{10^4}$, 1.0$\times{10^4}$, and 1.0$\times{10^4}$ for the 150, 250, 350, and 460$\:$GHz arrays, respectively. The average electrical phase responsivities on resonance are 1.4$\:$rad/pW, 1.5$\:$rad/pW, 2.1$\:$rad/pW, and 2.1$\:$rad/pW; the electrical noise equivalent powers are 45$\:\rm{aW/\sqrt{Hz}}$, 160$\:\rm{aW/\sqrt{Hz}}$, 80$\:\rm{aW/\sqrt{Hz}}$, and 140$\:\rm{aW/\sqrt{Hz}}$, at 12 Hz. In the OLIMPO cryostat, we measured the optical properties, such as the noise equivalent temperatures (NET) and the spectral responses. The measured NET$_{\rm RJ}$s are $200\:\mu\rm{K\sqrt{s}}$, $240\:\mu\rm{K\sqrt{s}}$, $240\:\mu\rm{K\sqrt{s}}$, and $\:340\mu\rm{K\sqrt{s}}$, at 12 Hz; under 78, 88, 92, and 90 mK Rayleigh-Jeans blackbody load changes respectively for the 150, 250, 350, and 460 GHz arrays. The spectral responses were characterized with the OLIMPO differential Fourier transform spectrometer (DFTS) up to THz frequencies, with a resolution of 1.8 GHz.Comment: Published on JCA

A systematic review and meta-analysis of germline BRCA mutations in pancreatic cancer patients identifies global and racial disparities in access to genetic testing

Background: Germline BRCA1 and BRCA2 mutations (gBRCAm) can inform pancreatic cancer (PC) risk and treatment but most of the available information is derived from white patients. The ethnic and geographic variability of gBRCAm prevalence and of germline BRCA (gBRCA) testing uptake in PC globally is largely unknown. Materials and methods: We carried out a systematic review and prevalence meta-analysis of gBRCA testing and gBRCAm prevalence in PC patients stratified by ethnicity. The main outcome was the distribution of gBRCA testing uptake across diverse populations worldwide. Secondary outcomes included: geographic distribution of gBRCA testing uptake, temporal analysis of gBRCA testing uptake in ethnic groups, and pooled proportion of gBRCAm stratified by ethnicity. The study is listed under PROSPERO registration number #CRD42022311769. Results: A total of 51 studies with 16 621 patients were included. Twelve of the studies (23.5%) enrolled white patients only, 10 Asians only (19.6%), and 29 (56.9%) included mixed populations. The pooled prevalence of white, Asian, African American, and Hispanic patients tested per study was 88.7%, 34.8%, 3.6%, and 5.2%, respectively. The majority of included studies were from high-income countries (HICs) (64; 91.2%). Temporal analysis showed a significant increase only in white and Asians patients tested from 2000 to present (P &lt; 0.001). The pooled prevalence of gBRCAm was: 3.3% in white, 1.7% in Asian, and negligible (&lt;0.3%) in African American and Hispanic patients. Conclusions: Data on gBRCA testing and gBRCAm in PC derive mostly from white patients and from HICs. This limits the interpretation of gBRCAm for treating PC across diverse populations and implies substantial global and racial disparities in access to BRCA testing in PC

A chemically etched corrugated feedhorn array for D-band CMB observations

We present the design, manufacturing, and testing of a 37-element array of corrugated feedhorns for Cosmic Microwave Background CMB) measurements between 140 and 170 GHz. The array was designed to be coupled to Kinetic Inductance Detector arrays, either directly (for total power measurements) or through an orthomode transducer (for polarization measurements). We manufactured the array in platelets by chemically etching aluminum plates of 0.3 mm and 0.4 mm thickness. The process is fast, low-cost, scalable, and yields high-performance antennas compared to other techniques in the same frequency range. Room temperature electromagnetic measurements show excellent repeatability with an average cross polarization level about − 20 dB, return loss about − 25 dB, first sidelobes below − 25 dB and far sidelobes below − 35 dB. Our results qualify this process as a valid candidate for state-of-the-art CMB experiments, where large detector arrays with high sensitivity and polarization purity are of paramount importance in the quest for the discovery of CMB polarization B-modes

The long duration cryogenic system of the OLIMPO balloon--borne experiment: design and in--flight performance

We describe the design and in--flight performance of the cryostat and the self-contained $^{3}$He refrigerator for the OLIMPO balloon--borne experiment, a spectrophotometer to measure the Sunyaev-Zel'dovich effect in clusters of galaxies. The $^{3}$He refrigerator provides the 0.3 K operation temperature for the four arrays of kinetic inductance detectors working in 4 bands centered at 150, 250, 350 and 460 GHz. The cryostat provides the 1.65 K base temperature for the $^{3}$He refrigerator, and cools down the reimaging optics and the filters chain at about 2 K. The integrated system was designed for a hold time of about 15 days, to achieve the sensitivity required by the planned OLIMPO observations, and successfully operated during the first long-duration stratospheric flight of OLIMPO in July 2018. The cryostat features two tanks, one for liquid nitrogen and the other one for liquid helium. The long hold time has been achieved by means of custom stiff G10 fiberglass tubes support, which ensures low thermal conductivity and remarkable structural stiffness; multi--layer superinsulation, and a vapour cooled shield, all reducing the heat load on the liquid helium tank. The system was tested in the lab, with more than 15 days of unmanned operations, and then in the long duration balloon flight in the stratosphere. In both cases, the detector temperature was below 300 mK, with thermal stability better than $\pm$ 0.5 mK. The system also operated successfully in the long duration stratospheric balloon flight