Integrated photon pairs source in silicon carbide based on micro-ring resonators for quantum storage at telecom wavelengths.

We present the design of an on-chip integrated photon pair source based on Spontaneous Four Wave Mixing (SFWM), implemented on a ring resonator in the 4H Silicon Carbide On Insulator (4H-SiCOI) platform, compatible with a solid state quantum memory in the telecommunications band. Through careful engineering of the waveguide dispersion and micro-ring resonator dimensions, we found solutions where the signal photons are emitted at 1536.48 nm with a bandwidth of ∼ 150 MHz, enabling the interaction with the hyperfine structure of Er 3 + ions. Simultaneously, the idler photons are generated at 1563.86 nm, matching the central wavelength of a specific channel in a commercial dense wavelength division multiplexing system. The proposed device fulfill all the spectral requirements in a simple ring-bus coupled waveguide configuration with design parameters within the range of reported values for similar resonators, making feasible its manufacturing with current fabrication capabilities.

Integrated photon pair source based on a silicon nitride micro-ring resonator for quantum memories.

We report the design of an integrated photon pair source based on spontaneous four-wave mixing (SFWM), implemented in an integrated micro-ring resonator in the silicon nitride platform (Si3N4). The signal photon is generated with emission at 606 nm and bandwidth of 3.98 MHz, matching the spectral properties of praseodymium ions (Pr), while the idler photon is generated at 1430.5 nm matching the wavelength of a CWDM channel in the E-band. This novel, to the best of our knowledge, device is designed to interact with a quantum memory based on a Y2SiO5 crystal doped with Pr3+ ions, in which we used cavity-enhanced SFWM along with dispersion engineering to reach the required wavelength and the few megahertz signal photon spectral bandwidth.

Surface plasmons in suspended graphene: launching with in-plane gold nanoantenna and propagation properties.

Graphene physics and plasmonics are two fields which, once combined, promise a variety of exciting applications. One of those applications is the integration of active nano-optoelectronic devices in electronic systems, using the fact that plasmons in graphene are tunable, highly confined and weakly damped. A crucial challenge remains before achieving these active devices: finding a platform enabling a high propagation of Graphene Plasmons Polaritons (GPPs). Suspended graphene presenting ultrahigh electron mobility has given rise to increasing interest. We numerically studied the plasmonic properties of suspended graphene. We propose a hybrid configuration and a set of conditions to launch graphene plasmons via an in-plane gold nanoantenna, for micrometric propagation of surface plasmons in suspended graphene. Finally, we propose a realistic optoelectronic device based on the use of suspended graphene.

Observation of near-field dipolar interactions involved in a metal nanoparticle chain waveguide.

We present near-field measurements of transverse plasmonic wave propagation in a chain of gold elliptical nanocylinders fed by a silicon refractive waveguide at optical telecommunication wavelengths. Eigenmode amplitude and phase imaging by apertureless scanning near-field optical microscopy allows us to measure the local out-of-plane electric field components and to reveal the exact nature of the excited localized surface plasmon resonances. Furthermore, the coupling mechanism between subsequent metal nanoparticles along the chain is experimentally analyzed by spatial Fourier transformation on the complex near-field cartography, giving a direct experimental proof of plasmonic Bloch mode propagation along array of localized surface plasmons. Our work demonstrates the possibility to characterize multielement plasmonic nanostructures coupled to a photonic waveguide with a spatial resolution of less than 30 nm. This experimental work constitutes a prerequisite for the development of integrated nanophotonic devices.

External quality control program of four blood cell counters.

OBJECTIVE: To evaluate an internal-external quality control program of four automated counters. METHODS: Every one or two weeks during 14 months, six direct cell parameters were measured in three fresh blood samples in four Coulter counters. The median per parameter of the working day was used to detect inaccuracies and if the participants' internal control program confirmed it, a recalibration of the parameter was performed. RESULTS: In 21 of 22 instances, the internal program confirmed an inaccuracy and a recalibration was done (4 leukocyte and 5 erythrocyte counts, 5 hemoglobins, 7 red-cell volumes). In these four parameters there were no large differences between the lowest and highest counter upon analyzing all results whereas all counters differed from one another in the parameters that cannot be recalibrated by the user (platelet volume, red-cell distribution width). CONCLUSIONS: 1. The program contributed to good accuracy and precision within-counters and good concordancy between-counters in the parameters that can be recalibrated. 2. The counter differences in red-cell distribution width were sufficiently large (up to 9%) to affect clinical interpretation. This poses the need of width distribution reference ranges for each counter.

[First two years of an external quality assurance program for urinalysis]. / Los dos primeros años del programa de evaluación externa de calidad en uroanálisis (PEECU).

OBJECTIVE: To analyze the first two years of a strip uroanalysis quality assurance scheme operating in Mexico. METHODS: The participants received 8 shipments of four controls each as dried tablets to be dissolved and analyzed with urine strips. The number of participants increased from < 50 in the 1st shipment to > 200 in the 8th. They assayed 6-10 analytes depending on the strip used and sent in 763 reports. For each report we calculated a score per analyte (n = 4), per shipment (n = 24 to 40) and a global score in the 8 shipments (n = 707 to 763 reports). The scores ranged from zero (excellent accuracy) to a maximum of 400 and were calculated by comparison with the modal value of about 600 American and Canadian laboratories which assayed the same controls using exclusively Bayer strips and instrumental readings. RESULTS: The best score was for nitrites (global score of 3 in 741 reports) and the worst for specific gravity (58 in 744 reports); the other analytes had scores from 11 to 19 (Table 1). The scores of four types of methods (Table 2) showed the best results with Bayer strips and instrumental readings (score of 13 in 469 reports) and the worst with strips of other suppliers (scores of 28 for visual and 31 for instrumental readings) and intermediate with visual readings of Bayer strips (score of 21). CONCLUSIONS: 1. Our results led us to the decision to exclude from the program participants who do not use Bayer strips as our program may disorient them instead of helping to improve their assays. 2. We confirmed that instrumental readings perform better than visual readings. 3. The causes of suboptimal performance in specific gravity need to be explored.