Stanislav Sima

Photonic services, their enablers and applications

The paper introduces photonic service as a new type of multi-domain, end-to-end network service, that besides traditional data transmission enables also non-data or real-time communication, e.g. the remote control and sharing of different, typically unique, devices. We proved the concept of photonic services on a specialized metrology application - comparison of time scales, where time offset between atomic clock is measured. The experiment has been conducted over distance of 550 km (342 miles).

Φ-OTDR signal amplification

Phase-sensitive optical time-domain reectometry (Φ-OTDR) seems to be the most appropriate solution for acoustic vibration along standard optical fiber detection. In general the sensing system measures phase changes of the received Rayleigh back-scattered signal in the fiber. Since the back-scattered signal intensity is decreased about tens of decibels in comparison to the forward propagating pulse power level, the received signal power level is very low. That is why the main limiting parameter of the system is the power level of the back-scattered signal, which limits maximum achievable distance. For long reach sensing it is necessary to create high power optical pulses with short time-duration. Direct pulse amplification by erbium doped fiber amplifier (EDFA) is an issue because of the pulses low repetition rate. We have designed and verified a simple method using a holding beam for amplifying of pulses with low repetition rate by standard telecommunication EDFA booster instead of deployment of an expensive optical shutter. A second CW laser with a different wavelength for EDFA stabilization is used in our setup. Because a pulse losses its energy during propagation in the fiber and with longer distances by 1st order Raman amplifier (RA). In telecommunications this amplifier is used to compensate for fiber losses. The second setup uses remote amplification by remotely pumped erbium doped fiber (EDF) placed after a few tens of kilometers of sensing fiber. A pump laser is placed in the transmitter part of the system from where EDF is pumped. In this paper, we present an overview of few techniques for Φ-ODTR signals amplification and their verification by measurement.

Photonic services enables real-time applications over long distances

The paper introduces photonic service as a new type of multi-domain, end-to-end network service, that besides traditional data transmission enables also non-data or real-time communication, e.g. the remote control and sharing of different, typically unique, devices. We proved the concept of photonic services on a specialized metrology application - comparison of time scales, where time offset between atomic clock is measured over distance of 560km.

Photonic Services and Their Applications

The poster addresses Photonic Services as a general approach to end-to-end connection over optical networks and possible types of applications that can benefit from them. Features and known challenges are highlighted. Also expected fields of application are listed and precise time transfer together with atomic clock comparison is discussed in detail with specific results.

Infrastructure Overview with Focus on Experimental Facility

CESNET’s main role is to run, maintain and provide services for users of Czech NREN called CESNET2. It has more than 5 thousand kilometres of leased fibres of which 360 kilometres are represented by the Experimental Facility. Connection to other NRENs (mostly represented by GEANT members) has capacity of 10Gbit, with exception of cz.NIC, where CESNET has 2x 10Gbit. Beyond this, CESNET also operates single fibre bidirectional transmission lines and offer several advanced services, mostly coming from its R&D activities. One example could be photonic service, based on pure fibre optic network advantages. Services such as wireless, security, storage, grid and others are mostly represented by particular CESNET departments.

Photonic services for real-time applications

The paper introduces photonic service as a new type of multi-domain, end-to-end network service, that besides traditional data transmission enables also non-data or real-time communication, e.g. the remote control and sharing of different, typically unique, devices. We proved the concept of photonic services on a specialized metrology application - comparison of time scales, where time offset between atomic clock is measured over distance of 550 km.

Dark fibre facilities for research and experimentation

This paper introduces the Czech National Research and Educational Network called CESNET2 and especially experimental facility. The paper also addresses a necessity of full access to the physical layer in experimental networking. Furthermore it summarizes research and experimental achievements and resources available for experimentation and formulates suggestions for the future international cooperation.