Phase noise characterization of sub-hertz linewidth lasers via digital cross correlation

Phase noise or frequency noise is a key metrics to evaluate the short term stability of a laser. This property is of a great interest for the applications but delicate to characterize, especially for narrow line-width lasers. In this letter, we demonstrate a digital cross correlation scheme to characterize the absolute phase noise of sub-hertz line-width lasers. Three 1,542 nm ultra-stable lasers are used in this approach. For each measurement two lasers act as references to characterize a third one. Phase noise power spectral density from 0.5 Hz to 0.8 MHz Fourier frequencies can be derived for each laser by a mere change in the configuration of the lasers. This is the first time showing the phase noise of sub-hertz line-width lasers with no reference limitation. We also present an analysis of the laser phase noise performance.Comment: 4 pages, 5 figure

Laser monitoring system for the CMS lead tungstate crystal calorimeter

We report on the multiple wavelength laser monitoring system designed for the CMS lead tungstate crystal calorimeter read-out with avalanche photodiodes (Barrel calorimeters) and vacuum phototriodes (End Cap calorimeters). Results are presented for the test beam performance of the system designed to achieve 0.5% relative inter-calibration of the optical transmittance for lead tungstate scintillation emission over nearly 80 000 channels. The system operates in continuous measurement cycles to follow each crystal?s evolution under irradiation and recovery periods foreseen during operation at the LHC

Accurate control of optoelectronic amplitude to phase noise conversion in photodetection of ultra-fast optical pulses

International audienc

Compact Low-Noise Photonic Microwave Generation From Commercial Low-Noise Lasers

We demonstrate how phase-locking a whispering gallery mode-stabilized semiconductor laser to a high-stability Erbium-based distributed feedback fiber laser makes an outstanding optical reference for photonic microwave generation using an optical frequency comb. Using only commercially available compact lasers, it allows generation of a 12 GHz microwave signal with absolute levels of phase noise below-47 dBc/Hz at 1 Hz and-170 dBc/Hz at 50 kHz from the carrier. Index Terms-Phase noise, microwave source, optical frequency comb, distributed feedback laser, whispering gallery mode resonator (WGMR)

Efficacy of cotrimoxazole (Sulfamethoxazole-Trimethoprim) as a salvage therapy for the treatment of bone and joint infections (BJIs).

INTRODUCTION:Cotrimoxazole (Sulfamethoxazole-Trimethoprim, SXT) has interesting characteristics for the treatment of bone and joint infection (BJI): a broad spectrum of activity with adequate bone diffusion and oral and intravenous formulations. However, its efficacy and safety in BJIs are poorly documented and its use remains limited. METHODS:We conducted a retrospective study in 2 reference centers for BJIs from 2013 to 2018 among patients treated with SXT for a BJI. Data were collected from patient's medical charts. Outcomes and adverse events were evaluated at day (D)7, D45 and D90. RESULTS:We analyzed 51 patients with a mean age of 60 ± 20 (SD) years of which 76% presented with an orthopedic device infection (ODI). Gram-negative bacilli (GNB) were involved in 47% of BJIs (n = 24). Moreover, they were often polymicrobial infections (41%). Doses of SXT ranged from 800/160mg bid (61%; n = 31) to 800/160mg tid (39%; n = 20). Median SXT treatment duration was 45 days (IQR 40-45). SXT was part of a dual therapy in 84% of patients (n = 43), associated mainly with fluoroquinolones (n = 17) or rifampicin (n = 14). Outcome was favorable at D7 in 98% (n = 50), at D45 in 88.2% (n = 45) and at D90 in 78.4% (n = 40). The second agent combined with SXT was not an independent factor of favorable outcome (p = 0.97). Adverse events were reported in 8% (n = 4) of patients, with a median of 21 days (IQR 20-30) from SXT initiation and led to discontinuation (n = 3). CONCLUSION:SXT appears to be effective for treatment of BJIs as a salvage therapy, even in GNB or polymicrobial infection, including ODI. Further data are needed to confirm SXT efficacy as an alternative oral regimen in BJIs

Record Ultra-low Phase Noise 12 GHz Signal Generation with a Fiber Optical Frequency Comb and Measurement

International audienc

Ultra-short optical pulses leading to ultra-stable photonic microwave generation

International audienc

Ultra-short optical pulses leading to ultra-stable photonic microwave generation

International audienc

Ultra-short optical pulses leading to ultra-stable photonic microwave generation

International audienc

Record Ultra-low Phase Noise 12 GHz Signal Generation with a Fiber Optical Frequency Comb and Measurement

International audienceWe demonstrate a 12 GHz signal with a record absolute phase noise of -167 dBc/Hz at 10 kHz and -170 dBc/Hz at 100 kHz. We have developed a specific measurement setup for charactering this ultra-low phase noise