Cascaded multiplexed optical link on a telecommunication network for frequency dissemination

Abstract

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 x 10(-15) at one second measurement time and 5 x 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.

Simultaneous remote transfer of accurate timing and optical frequency over a public fiber network

“…This method of accurate time transfer can be extended to segmented optical links by the use of intermediate optical regeneration stations [2,3], which include RF signal processing techniques and station delay calibration procedures. This method can be improved for example by developing new modems with wider pseudo-random codes.…”

“…Recently, ground-breaking frequency transfer has been demonstrated on a record distance of 920 km on dedicated fiber [1]. We extended this technique to public fiber networks with simultaneous data traffic, providing a scalable technique for extension to the continental level [2,3]. This approach is much more stable and accurate than satellitebased frequency comparisons using the Global Navigation Satellite System (GNSS), or other satellite-based techniques.…”

Frequency and time transfer for metrology and beyond using telecommunication network fibres

“…The apparatus is designed to operate autonomously outside the lab. Specifically, no stable RF oscillator is required for the transfer of the ultra-stable signal to the next fibre span [25]. At the input, the beat-note signal detected on the photodiode PD1 is used to phase-lock the local laser to the incoming signal.…”

“…The high sensitivity detection of the optical phase using heterodyne methods in conjunction with spectrally very pure lasers, are the basic tools to achieve low-noise optical frequency transfer. In the last decade, several experiments in Europe, USA and Japan have explored the limits of this method, paving the way for a new generation of ultra-stable optical networks [18,[21][22][23][24][25][26][27][28][29][30][31]. A groundbreaking frequency transfer has been demonstrated on a record distance of 920 km and even 1840 km on a dedicated fibre network [27,32].…”

Transfert de fréquence par fibre optique en métrologie

“…Le bruit du lien libre est considérablement augmenté par rapport à la liaison plus courte de 108 km. Néanmoins, après correction du bruit de propagation, la stabilité en boucle fermée atteint quelques 10 −15 à 1 s (pour une bande passante de mesure de 10 Hz) pour franchir la gamme des 10 −19 audelà de 30 000 s [40]. Au-delà de cette performance, il faut souligner que le fonctionnement du réseau de télé-communication n'a pas été affecté par le signal métrolo-gique et c'est ainsi la première fois qu'un signal métro-logique a pu être propagé sur une liaison opérationnelle intercités.…”