Harald Schmuck

Coarse WDM/CDM/TDM concept for optical packet transmission in metropolitan and access networks supporting 400 channels at 2.5 Gb/s peak rate

To improve the networking flexibility in the metropolitan and access area, the granularity in the optical domain has to be increased above that in the core network requiring more channels at lower bit rates. Pure dense wavelength division multiplexing (DWDM) as it is applied in the core does not seem to meet this requirement at affordable cost. We propose and analyze a network based on hybrid optical multiplexing techniques including wavelength, code, and time division multiplexing. Applied to optical packet transmission this approach enables several 100 all-optical channel between end users and headend with average bit rates up to 100 Mb/s per channel while keeping the installation and maintenance cost at a minimum.

Beneficial OLT transmitter and receiver concepts for NG-PON2 using semiconductor optical amplifiers [invited]

Optical line termination transmitter (Tx) and receiver (Rx) concepts using a semiconductor optical amplifier (SOA) for the next generation of passive optical networks (NG-PON2) are experimentally compared. In general, a single SOA per wavelength channel at the Tx and a configuration comprising a single SOA followed by avalanche photodiodes (APDs) at the Rx are beneficial in terms of signal quality and power dynamic range. Additionally, we introduce a cost-effective bidirectional SOA approach for simultaneous upstream preamplification and downstream boosting. Our results indicate its feasibility for mid-class loss budget classes of NG-PON2.

Demonstration of an SOA-assisted open metro-access infrastructure for heterogeneous services

An open converged metro-access network approach allows for sharing optical layer resources like fibers and optical spectrum among different services and operators. We demonstrated experimentally the feasibility of such a concept by the simultaneous operation of multiple services showing different modulation formats and multiplexing techniques. Flexible access nodes are implemented including semiconductor optical amplifiers to create a transparent and reconfigurable optical ring network. The impact of cascaded optical amplifiers on the signal quality is studied along the ring. In addition, the influence of high power rival signals in the same waveband and in the same fiber is analyzed.

Amplification of advanced modulation formats with a semiconductor optical amplifier cascade.

The convergence of optical metro networks and access networks extends the area of network coverage, and therefore requires the use of optical amplifiers. For this purpose, semiconductor optical amplifiers (SOA) would be attractive, because they are broadband, can be centered between 1250 nm and 1600 nm, and because they are cheap in production and operation. We show that signals encoded with advanced modulation formats such as BPSK, QPSK, 8PSK, and 16QAM can be amplified by a cascade of at least four SOAs. This enables high-capacity paths with a capacity in the order of Tbit/s for converged metro-access networks.

Cost efficient non-service interrupting monitoring of optical fiber links in FTTH / FTTB networks

We present recent advances in low cost fiber monitoring techniques for FTTH/FTTB networks employing integrated means for localizing fiber faults and for testing fiber connectivity in PONs.

Cross-talk analysis & mitigation for TWDM-PON upstream path

Various cases of cross-talk mechanisms occurring in a TWDM-PON are analyzed in simulations and experiments. Power penalty degradations and limitations of photonic component technologies are described and mitigation techniques enabling such NG-PON2 systems are introduced.

In-service monitoring of PON access networks with powerline independent devices

In this paper we describe and demonstrate a new remote in-service monitoring technique for passive optical access networks. New microwatt off-grid powered devices are introduced that may be installed at any location in the network. These monitors are equipped with a unique software-defined address, allow status monitoring of network parameters, facilitate the integration of remote active elements such as switches, and scale up easily to thousands of devices. Such monitors may be used to identify and measure the power levels and connection availability of a customers site independent of the subscribers optical network termination (ONT). Even physical disconnection of a rogue or erroneous ONT is demonstrated. A hardware implementation using off-the-shelf components together with a special communication protocol was successfully demonstrated in a gigabit passive optical network (GPON) testbed, where random data were transmitted. The lowest power consumption with less than 2 μWallows for powering with an optical supply channel or a small battery that lasts for a decade.

Wavelength-transparent long-reach-high-split TWsDM-PON utilized by a non-gated parallel cascade of linear SOAs

We demonstrate the first long-reach and high-split TWsDM-PON utilizing a non-gated parallel cascade of linear SOAs. A fiber reach of up to 100 km and up to 2048 customers are achieved in non-wavelength routed outside plants.

Embedded OTDR measurement range extension for future metro-access networks employing in-line SOAs

We demonstrate for the first time the measurement range extension of an embedded OTDR system employing SOA within the fiber network. eOTDR monitoring across multiple SOA-amplified fiber segments with simultaneously GPON downstream transmission is achieved.

Optical line termination transceiver with a bi-directional SOA for application in type-A NG-PON2 links

The first NG-PON2 type-A-link OLT transceiver comprising a bi-directional SOA is experimentally assessed. Sufficient downstream transmitter output power and upstream receiver sensitivity is simultaneously demonstrated for E2 budget class. The influence of filter bandwidth and APD / PIN receiver is investigated.