Abstract: The invention relates to a method of operating a first optical network element (100), particularly an optical network unit, ONU, wherein said method comprises the following steps: performing a coarse tuning process (2100) of at least one transmission wavelength which is used by said first optical network element (100) for transmitting an optical signal to a second optical network element (200), particularly an optical line terminal, OLT, and performing a fine tuning process (2200) of said at least one transmission wavelength, wherein said fine tuning process (2200) is preferably performed after said coarse tuning process (2100).

Abstract: An optical transmission system method including generating for a tunable laser a pilot tone having an adjustable pilot tone frequency identifying a wavelength division multiplexing channel used by the tunable laser; multiplying the pilot tone with pilot tone data to provide a pilot tone data signal; supplying the pilot tone data signal and a high frequency data signal to the tunable laser generating an optical laser signal output by the tunable laser responsive to the supplied signals; transporting the optical laser signal to a central wavelength to locker; converting the received optical laser signal to provide a pilot tone data signal for wavelength division multiplexing channels demodulated to detect the pilot tone and the pilot tone data for each individual wavelength division multiplexing channel; and identifying the wavelength division multiplexing channel on the basis of the pilot tone frequency of the detected pilot tone and evaluating the pilot tone data.

Abstract: The invention relates to a method of operating a primary optical node, particularly an optical line terminal (OLT), for an optical communications system, wherein said OLT is configured to receive at least one upstream optical signal (uos) from at least one secondary optical node, particularly an optical networking unit (ONU), within at least a first wavelength range (wr1), and to transmit at least one downstream optical signal (dos) to said at least one ONU within at least a second wavelength range (wr2), wherein said OLT determines a currently unused wavelength subrange (wsr2) within said first wavelength range (wr1), assigns a specific target wavelength (?t) within said currently unused wavelength subrange (wsr2) to said ONU, signals said target wavelength (?t) to said ONU, receives an upstream signal (us) from said ONU, and provides feedback information to said ONU.

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: The present invention embraces an optical wavelength division multiplex (WDM) transmission system, especially a WDM passive optical network, typically including a central node having a first and a second WDM port and a remote node having a first and a second WDM port and a plurality of channel ports, the central node first WDM port being connected to the remote node first WDM port via a bidirectional single-fiber optical working path and the central node second WDM port being connected to the remote node second WDM port via a single-fiber bidirectional optical protection path, and a group of basic optical node units (ONU's) each of which is connected to a respective remote node channel port via a bidirectional optical ONU path, each ONU including an optical receiver for receiving a downstream optical channel signal and an optical tunable transmitter for creating an upstream channel signal.

Abstract: The invention relates to a method of operating a primary optical node, particularly an optical line terminal (OLT), for an optical communications system, wherein said OLT is configured to receive at least one upstream optical signal (uos) from at least one secondary optical node, particularly an optical networking unit (ONU), within at least a first wavelength range (wr1), and to transmit at least one downstream optical signal (dos) to said at least one ONU within at least a second wavelength range (wr2), wherein said OLT determines a currently unused wavelength subrange (wsr2) within said first wavelength range (wr1), assigns a specific target wavelength (?t) within said currently unused wavelength subrange (wsr2) to said ONU, signals said target wavelength (?t) to said ONU, receives an upstream signal (us) from said ONU, and provides feedback information to said ONU.

Abstract: An optical transmission system method including generating for a tunable laser a pilot tone having an adjustable pilot tone frequency identifying a wavelength division multiplexing channel used by the tunable laser; multiplying the pilot tone with pilot tone data to provide a pilot tone data signal; supplying the pilot tone data signal and a high frequency data signal to the tunable laser generating an optical laser signal output by the tunable laser responsive to the supplied signals; transporting the optical laser signal to a central wavelength to locker; converting the received optical laser signal to provide a pilot tone data signal for wavelength division multiplexing channels demodulated to detect the pilot tone and the pilot tone data for each individual wavelength division multiplexing channel; and identifying the wavelength division multiplexing channel on the basis of the pilot tone frequency of the detected pilot tone and evaluating the pilot tone data.

Abstract: The present invention embraces an optical wavelength division multiplex (WDM) transmission system, especially a WDM passive optical network, typically including a central node having a first and a second WDM port and a remote node having a first and a second WDM port and a plurality of channel ports, the central node first WDM port being connected to the remote node first WDM port via a bidirectional single-fiber optical working path and the central node second WDM port being connected to the remote node second WDM port via a single-fiber bidirectional optical protection path, and a group of basic optical node units (ONU's) each of which is connected to a respective remote node channel port via a bidirectional optical ONU path, each ONU including an optical receiver for receiving a downstream optical channel signal and an optical tunable transmitter for creating an upstream channel signal.

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: The invention relates to a method of operating a first optical network element (100), particularly an optical network unit, ONU, wherein said method comprises the following steps: performing a coarse tuning process (2100) of at least one transmission wavelength which is used by said first optical network element (100) for transmitting an optical signal to a second optical network element (200), particularly an optical line terminal, OLT, and performing a fine tuning process (2200) of said at least one transmission wavelength, wherein said fine tuning process (2200) is preferably performed after said coarse tuning process (2100).