Digital control of residual amplitude modulation at the 10 level for ultra-stable lasers.

The stabilization of lasers on ultra-stable optical cavities by the Pound-Drever-Hall (PDH) technique is a widely used method. The PDH method relies on the phase-modulation of the laser, which is usually performed by an electro-optic modulator (EOM). When approaching the 10 fractional frequency stability level, this technology requires an active control of the residual amplitude modulation (RAM) generated by the EOM in order to bring the frequency stability of the laser down to the thermal noise limit of the ultra-stable cavity.

Association of Autofluorescence-Based Detection of the Parathyroid Glands During Total Thyroidectomy With Postoperative Hypocalcemia Risk: Results of the PARAFLUO Multicenter Randomized Clinical Trial.

Importance: Because inadvertent damage of parathyroid glands can lead to postoperative hypocalcemia, their identification and preservation, which can be challenging, are pivotal during total thyroidectomy.

Objective: To determine if intraoperative imaging systems using near-infrared autofluorescence (NIRAF) light to identify parathyroid glands could improve parathyroid preservation and reduce postoperative hypocalcemia.

Design, Setting, And Participants: This randomized clinical trial was conducted from September 2016 to October 2018, with a 6-month follow-up at 3 referral hospitals in France.

Exploring gravity with the MIGA large scale atom interferometer.

We present the MIGA experiment, an underground long baseline atom interferometer to study gravity at large scale. The hybrid atom-laser antenna will use several atom interferometers simultaneously interrogated by the resonant mode of an optical cavity. The instrument will be a demonstrator for gravitational wave detection in a frequency band (100 mHz-1 Hz) not explored by classical ground and space-based observatories, and interesting for potential astrophysical sources.

Observation of Atom-Wave Beats Using a Kerr Modulator for Atom Waves.

A phase modulation puts the atom in a coherent superposition of quantum states with different kinetic energies. We have detected the interference of such modulated waves at the output of our atom interferometer, and we have observed beats at the difference of the modulation frequencies and its harmonics, in good agreement with theory. The phase modulations were produced by a Kerr phase modulator, i.

Note: A passively cooled heat pipe for spectroscopy.

We have developed and characterized a heat pipe for lithium spectroscopy, which is cooled only by air-convection, although its operating temperature is 330 °C: its construction is simple, of moderate cost and it is very reliable. A thermal model proves that heat-pipes without water cooling can be used up to considerably higher temperatures.