Armenia and Armenians in Roman Numismatics

Ancient Armenian sources are very scarce and do not permit a thorough understanding of Ancient Armenia. For this reason, all available sources relevant to Armenia need to be consid­ered and studied. This is notably the case for Roman Coinage, where issues related to Armenia were struck over the course of 200 years. This paper examines how Roman coinage is able to in­fluence our understanding of Roman, Armenian and Parthian relationships. The study begins with the analysis of the monetary iconography of Armenia and Armenians on Roman coinage through their attributes and postures. Following the first part, the study questions the Roman coinage as a source of ideological representations of the events. Indeed, the issues do not reflect the intricate relationships of the Romans, Armenians and Parthians, but rather highlight Roman victories and the image of the Emperor. Despite this Roman prism, the last part of the article shows that it is possible to use the coinage as a source for Roman, Armenian and Parthian reationship studies

Cascaded multiplexed optical link on a telecommunication network for frequency dissemination

We demonstrate a cascaded optical link for ultrastable frequency dissemination comprised of two compensated links of 150 km and a repeater station. Each link includes 114 km of Internet fiber simultaneously carrying data traffic through a dense wavelength division multiplexing technology, and passes through two routing centers of the telecommunication network. The optical reference signal is inserted in and extracted from the communication network using bidirectional optical add-drop multiplexers. The repeater station operates autonomously ensuring noise compensation on the two links and the ultra-stable signal optical regeneration. The compensated link shows a fractional frequency instability of 3 \times 10-15 at one second measurement time and 5 \times 10-20 at 20 hours. This work paves the way to a wide dissemination of ultra-stable optical clock signals between distant laboratories via the Internet network

Ultralow frequency noise laser by locking to an optical fiber delay line

International audienceWe report the frequency stabilization of an erbium-doped fiber distributed-feedback laser using an all-fiber based Michelson interferometer of large arm imbalance. The interferometer uses a 1 km SMF-28 optical fiber spool and an acousto optic modulator allowing heterodyne detection. The frequency noise power spectral density is reduced by more than 40 dB for Fourier frequencies ranging from 1 Hz to 10 kHz, corresponding to a level well below 1 Hz^2/Hz over the whole range. It reaches 10^{-2} Hz^2/Hz at 1 kHz. Between 40 Hz and 30 kHz, the frequency noise is shown to be comparable to the one obtained by Pound-Drever-Hall locking to a high finesse Fabry-Perot cavity. Locking to a fiber delay line could consequently represent a reliable, simple and compact alternative to cavity stabilization for short term linewidth reduction

Asservissement de deux lasers séparés d'une fréquence micro-onde sur un interféromètre à fibre

National audienceNous présentons une méthode permettant d'asservir simultanément sur un interféromètre deux lasers séparés d'une fréquence micro-onde. Cette méthode repose sur l’utilisation de la technique Pound- Drever-Hall [2] qui est très largement utilisée pour l’asservissement sur les cavités Fabry-Perot. Les deux lasers sont des diodes lasers bas bruit (modèle ORION), émettant autour de 1542 nm et séparés de 20 GHz. La sortie de chacun des lasers est modulée en phase par un modulateur électrooptique fibré (EOM) alimenté par un signal RF de fréquence différente (ν1=14 MHz et ν2=34 MHz)

High-resolution optical frequency dissemination on a telecommunication network with data traffic

We transferred the frequency of an ultra-stable laser over a 108 km urban fiber link comprising 22 km of optical communications network fiber simultaneously carrying Internet data traffic. The metrological signal and the digital data signal are transferred on two different frequency channels in a dense wavelength division multiplexing scheme. The metrological signal is inserted into and extracted from the communications network by using bidirectional off-the-shelf optical add-drop multiplexers. The link-induced phase noise is measured and cancelled with round-trip technique using an all-fiber-based interferometer. The compensated link shows an Allan deviation of a few 10-16 at one second and below 10-19 at 10,000 seconds. This opens the way to a wide dissemination of ultra stable optical clock signals between distant laboratories via the Internet network

Search for dark matter with EDELWEISS-III excluding background from muon-induced neutrons

The aim of the EDELWEISS-III experiment is to detect the elastic scattering of WIMPs from the galactic dark matter halo on germanium bolometers. Neutrons produced by cosmic muons reaching the underground laboratory are a problematic background, as they can mimic a WIMP interaction. Within this thesis, it was shown that the expected background induced by muons is negligible for the WIMP search analyses of the Run308 data and won\u27t limit the future sensitivity of the experiment

In situ characterization of an optical cavity using atomic light shift

We report the precise characterization of the optical potential obtained by injecting a distributed-feedback erbium-doped fiber laser (DFB EDFL) at 1560 nm to the transversal modes of a folded optical cavity. The optical potential was mapped in situ using cold rubidium atoms, whose potential energy was spectrally resolved thanks to the strong differential light shift induced by the 1560 nm laser on the two levels of the probe transition. The optical potential obtained in the cavity is suitable for trapping rubidium atoms, and eventually to achieve all-optical Bose-Einstein condensation directly in the resonator.Comment: 3 pages, 4 figure

An agile laser with ultra-low frequency noise and high sweep linearity

We report on a fiber-stabilized agile laser with ultra-low frequency noise. The frequency noise power spectral density is comparable to that of an ultra-stable cavity stabilized laser at Fourier frequencies higher than 30 Hz. When it is chirped at a constant rate of ~ 40 MHz/s, the max non-linearity frequency error is about 50 Hz peak-to-peak over more than 600 MHz tuning range. The Rayleigh backscattering is found to be a significant frequency noise source dependent on fiber length, chirping rate and the power imbalance of the interferometer arms. We analyze this effect both theoretically and experimentally and put forward techniques to reduce this noise contribution.Comment: 14 pages, 11 figures, accepted by Optics Expres

Optical linewidth of a passively mode-locked semiconductor laser

We measured the optical linewidths of a passively mode-locked quantum dot laser and show that, in agreement with theoretical predictions, the modal linewidth exhibits a parabolic dependence with the mode optical frequency. The minimum linewidth follows a Schawlow-Townes behavior with a rebroadening at high power. In addition, the slope of the parabola is proportional to the RF linewidth of the laser and can therefore provide a direct measurement of the timing jitter. Such a measurement could be easily applied to mode-locked semiconductor lasers with a fast repetition rate where the RF linewidth cannot be directly measured

Ultra-Low Noise Microwave Extraction from Fiber-Based Optical Frequency Comb

In this letter, we report on all-optical fiber approach to the generation of ultra-low noise microwave signals. 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 an unprecedented relative phase noise of -111 dBc/Hz at 1 Hz from the carrier.The residual frequency instability of the microwave signals derived from the two optical frequency combs is below 2.3 10^(-16) at 1s and about 4 10^(-19) at 6.5 10^(4)s (in 5 Hz bandwidth, three days continuous operation).Comment: 12 pages, 3 figure