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Mechanical vibration induced frequency noise is dominated at low Fourier frequencies in a fiber spool stabilized laser. Environmental vibration causes mechanical deformations in the fiber which induce phase fluctuations and then convert into excess frequency noise to the lasers. Therefore, the spool which supports the fiber plays a critical role in this frequency noise conversion. We have studied...
We report on our fiber-based mode-locked laser approach to the generation of ultra-low noise microwave signals, and its use for frequency metrology. We make use of two erbium fiber mode-locked lasers phase locked to a common ultra stable laser source to generate an 11.55 GHz signal with a relative phase noise of −111 dBc/Hz at 1 Hz from the carrier. The corresponding residual frequency instability...
We present here a new approach consisting in using part of an optical telecommunications network carrying simultaneously data traffic. Our 108 km comprises 86 km of dedicated fibre and 22 km of fibre from the French national telecommunications network for technology, education and research (RENATER). The link is a loop with both ends located in Observatoire de Paris to characterize the link stability...
Very low frequency noise lasers are important tools for many applications such as high-resolution spectroscopy, optical atomic clock local oscillator, interferometric sensor (including gravitational waves detection), and coherent optical communications systems. Laser linewidth is usually reduced by locking to an ultra-stable optical cavity, using the Pound-Drever-Hall method. It led to fractional...
We report on a prototype endoscope with tunable-focus liquid microlenses actuated through infrared (IR) light integrated at its distal end. Tunable-focus microlenses scanning the areas of interest with minimal movements of the scopes themselves would greatly advance endoscopy. Multiple IR light-responsive hydrogel posts were used to tune the focal length of the microlens, which were formed by a curved...
We demonstrate the use of a fiber-based femtosecond laser locked onto an ultrastable optical cavity to generate a low-noise microwave reference signal. Comparison with both a cryogenic sapphire oscillator (CSO) and a titanium-sapphire-based optical frequency comb system exhibit a stability of about 3 times 10-15 between 1 and 10 s. The microwave signal from the fiber system is used to perform Ramsey...
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