Abstract: The invention relates to a method for controlling the center wavelength of at least one narrow band WDM optical channel transmitting device in a WDM network. A reflected signal portion of a WDM channel signal is evaluated at the location of a WDM transmitting device. In order to generate the reflected signal portion, the optical multiplexing device or an additional reflective filter may be used, the additional filter revealing a low reflectivity at the desired channel center wavelength and a sharply increasing reflectivity adjacent thereto. The center wavelength of the WDM transmitting device is tuned to this target center wavelength by wavelength-modulating the center wavelength with a predetermined low modulation frequency and predetermined wavelength amplitude. The center wavelength of the WDM transmitting device is tuned such that the first order modulation frequency component of the reflected signal portion is minimized.

Abstract: A backplane arrangement is provided for an electronic mounting rack with a base backplane with several contact strips, wherein a free space, into which at least one additional backplane can be inserted, is provided on the base backplane.

Abstract: Provided is an optical network system and optical network unit (ONU) structure enabling a passive optical access network having a meshed structure with at least two central nodes and plurality of ONUs. One embodiment employs a partially or fully meshed structure of optical fibers between customer locations and multiple optical line terminal (OLT) locations creating a passive optical access network. The ONUs can communicate with a neighboring OLT or ONU using a symmetrical or asymmetrical TDM scheme, and convert between the different TDM schemes. For this purpose, the ONU structure includes two transceiver units, one connected to the western network port and the other to the eastern. The ONU can establish communication between either network port and a further ONU or an OLT, with the ONU controller adapted for passing through data, and converting TDM schemes.

Abstract: An optical transceiver unit for an optical WDM transmitting and receiving device is taught, with a transmitting unit to which a data signal can be fed to a specified channel input port of a multiplexer unit, wherein a separate channel wavelength is allocated to each channel input port, and the transmitting unit can be tuned with respect to optical carrier wavelength across a specified range of wavelengths. The transmitting unit is constructed so that, within the specified range of wavelengths, discrete wavelengths can be set that correspond to the channel wavelengths. In tuning mode, the controller unit can drive the transmitting unit so that the possible channel wavelengths are scanned through. The controller unit evaluates the reception signal fed to it from the receiving unit for whether abort criteria for tuning mode have been fulfilled or not, wherein the scanning process is continued until the abort criteria are fulfilled.

Abstract: A data transmission method for transmitting a digital optical signal over an optical transmission link includes creating a digital optical signal defining at least two service levels, each service level transporting information via a modulation scheme comprising at least three different modulation symbols. The data transmission method also includes transmitting the digital optical signal over the transmission link and receiving the transmitted digital optical signal at a remote end of the transmission link by demodulating the received signal and extracting the information of the at least two service levels. In case that the transmission performance is below a given threshold due to increased constraints of the transmission link a compensating action is taken to drop at least one of the service levels from the optical signal or to determine parameters associated with the transmission so as to increase one of the service levels to a predetermined quality level.

Abstract: An optical frequency locking method tunes each of a plurality of narrow-band optical channel transmit signals (having arbitrary channel frequency spacings) to a dedicated optical channel frequency. The method includes tapping-off a portion of the optical power of the respective channel transmit signal and filtering the tapped-off channel transmit signal using at least one optical filter device. The method also includes monitoring, as an optical input signal, the optical power of the respective channel transmit signal supplied to the at least one optical filter device and, as an optical output signal, the optical power of the filtered channel transmit signal. The method further includes tuning, within a predetermined locking range for the dedicated optical channel frequency, the optical frequency of the respective channel transmit signal such that a predetermined value for the ratio of the output signal and the input signal is reached.

Abstract: A method for protecting a passive optical transmission network comprising an optical line terminal (OLT) at least one remote node (RN), and a plurality of network termination nodes (ONU) A bidirectional optical signal transmission can be established between each ONU and the OLT via a first bidirectional optical transmission route by means of which an optical wavelength-multiplexed signal is transmitted in the downstream direction from the OLT to the one or more RNs and in the upstream direction from the one or more RNs to the OLT. A second bidirectional optical transmission route is provided between the OLT and the RNs where the wavelength-multiplexed signal is fed in the upstream direction both to the first and second optical transmission routes. On the detection of a fault state on the first or second optical transmission route, the OLT is switched to the other corresponding optical transmission route.

Abstract: Schemes are provided for starting up optical transmission links where, after a link interruption, endpoints switch into a startup mode original detection state, and a query-transmit pulse goes out at both end points at given time intervals. In a “TRANSMITTED” handshake mode, in a loop to be passed through n times, and at least once, after the transmission of a transmit pulse, it is detected whether a received pulse is received within a given time span. If no received pulse is received, then the mode is ended and the system is returned to the original detection state. If a received pulse is received, it is answered with another transmit pulse. After the last transmit pulse, if another received pulse occurs within a given time span, the link is activated. If not, the “TRANSMITTED” handshake mode ends and the system enters the original detection state.