Abstract: The invention relates to a method for monitoring a detachable fiber-optic connection, especially in a fiber-optic transmission device or system, comprising the steps of transmitting a wanted optical transmission signal carrying information data to be transmitted to at least one fiber-optic connection, a predetermined portion of the power of said optical transmission signal being reflected at the at least one fiber-optic connection depending on the status and properties of the at least one fiber-optic connection, creating a detection signal by detecting said reflected predetermined portion of the power of said optical transmission signal, monitoring and evaluating the detection signal as a function of time and creating a “DETECT” signal if the detection signal or a signal derived from the detection signal reveals a characteristic change in its course in time. Further, the invention relates to a corresponding device adapted to realize this method.

Abstract: The invention relates to a fractional bit encoder (1) and a method for encoding a data stream into code word identifiers for a physical line encoder (13), wherein said fractional bit encoder (1) comprises a (1:K) demultiplexer (3) for a de-multiplexing a received data stream into a predetermined number (K) of bit streams, a first (K1:n) multiplexer (4) for re-multiplexing a first number (K1) of said K bit streams onto n parallel lines transporting n re-multiplexed bit streams and a second multiplexer (5) re-multiplexing a second number (K2) of said K bit streams (K2:1) onto a single line transporting one further re-multiplexed bit stream, wherein n=[ld(M)] and M being a configurable number of different code word identifiers, a class detector (7) which evaluates the first n re-multiplexed bit streams to determine a class of the respective bit combination and a word encoder (10) which encodes the respective bit combination depending on the determined class of the bit combination.

Abstract: The invention provides a method and a system for localizing an attenuation change location in an optical waveguide, wherein the attenuation change location can be determined depending on a time difference (?T) between signal power change instants of optical signals having different wavelengths (?1, ?2) that are transmitted via the optical waveguide.

Abstract: The invention relates to an apparatus and a method for modulation of an optical signal with a data signal, said apparatus (6) comprising a configurable digital encoding unit (8) encoding data of said data signal to provide an encoded modulation control signal (EMCS), and a signal modulation unit (9) modulating said optical signal with respect to its signal phase and/or signal amplitude in orthogonal polarization directions in response to said encoded modulation control signal (EMCS) to generate a multi-dimensional optical signal vector.

Abstract: The invention relates to a method for monitoring an optical amplifier, in particular, an optical fiber amplifier which has an optical input port and an optical output port. The optical pumping power of the amplifier is presumed to be directly proportional to the electrical pumping current, with a proportionality constant that decreases over time due to degradation. The functional dependence of the optical pumping power on the optical input signal power or the optical output signal power is determined at least for the predetermined nominal value of the optical gain. These relationships may be combined with certain measured values to determine the instantaneous optical pumping power, the instantaneous proportionality constant, and the maximum values for the optical input and output signal powers. These calculated parameters may be used to ensure that an increase of input power will not reduce the optical gain.

Abstract: The invention relates to a method of operating an optical transmission system (100a, 100b, 100c), wherein at least one optical data signal is transmitted over an optical transmission link (120), which particularly comprises at least one optical fiber (120a). The inventive method is characterized by modulating (200) said data signal with a test signal (s) having a predetermined modulation frequency fmod to obtain a modulated data signal (Pin), by receiving (210) a reflected portion (Pback) of said modulated data signal (Pin), and by determining (220) a fiber quality measure (a) depending on said received reflected portion (Pback) of said modulated signal (Pin).

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: The invention relates to an optical circuit structure for realizing a higher-order node in an optical transmission network with a number N of bidirectional remote ports, wherein an optical receive wavelength division multiplexed signal with a set of optical receive channels can be fed to each remote port and wherein an optical transmit wavelength division multiplexed signal with a set of optical transmit channels can be output from each remote. The optical drop channel means and the optical add and cross-connect means include exclusively optical splitter units, optical demultiplexing units, and optical add units, wherein for generating each transmit wavelength division multiplexed signal for a certain remote port, the receive wavelength division multiplexed signals of several or all of the other remote ports are guided as cross-connect wavelength division multiplexed signals toward the certain remote port.

Abstract: The invention relates to a method and an arrangement for measuring power for an optical user signal transmitted via an optical fiber by converting the transmitted optical user signal into a pulsed optical measurement signal, the pulse repetition rate of which is dependent on the power of the transmitted optical user signal, and evaluating the pulse repetition rate of the converted optical measurement signal in order to ascertain the power of the optical user signal transmitted via the optical fiber.

Abstract: Disclosed are a device and a method for transmitting an optical data signal over an optical transmission channel, comprising a differential phase shift keying unit for differential phase shift keying of at least one serial data stream to generate a differential phase shift keying coded data stream; an amplitude shift keying unit for amplitude coding of at least two further serial data streams that can be selectively activated to generate an amplitude shift keying coded data stream; and a modulation unit for generating an optical data signal in accordance with a control signal that is, formed from the generated differential phase shift keying coded data stream and from the generated amplitude shift keying coded data stream.

Abstract: The invention relates to a method for monitoring an optical amplifier, in particular, an optical fiber amplifier, which has an optical input port (3) and an optical output port (5), between which an optical path (7) extends, in which an optical amplification means (9) is arranged, which has at least one pumping source (19), whose optical power (Ppump) is supplied via a coupling unit (11) to optical path (7), wherein the optical input signal power (Pin) supplied to input port (3) of optical amplifier (1) and/or the optical output signal power (Pout) emitted at output port (5) of optical amplifier (1) is detected and wherein the gain (G) of optical amplifier (1) is to be controlled or regulated to a predetermined nominal value. According to the invention, the optical pumping power (Ppump) is presumed to be approximately directly proportional to the electrical pumping current (Ipump), the time-variant proportionality constant subject to a degradation over time being designated with ?(t).

Abstract: The invention provides a method and a system for localizing an attenuation change location in an optical waveguide, wherein the attenuation change location can be determined depending on a time difference (?T) between signal power change instants of optical signals having different wavelengths (?1, ?2) that are transmitted via the optical waveguide.

Abstract: The invention relates to an optical circuit structure for realizing a higher-order node in an optical transmission network with a number N of bidirectional remote ports, wherein an optical receive wavelength division multiplexed signal with a set of optical receive channels can be fed to each remote port and wherein an optical transmit wavelength division multiplexed signal with a set of optical transmit channels can be output from each remote port, wherein an optical center wavelength is allocated to each receive channel or transmit channel, and wherein the number N is greater than or equal to three, with a number M of bidirectional local ports, wherein M is greater than or equal to one and less than or equal to N, wherein exactly one defined remote port is associated with each local port and wherein one or more optical add channels can be fed to each local port and one or more optical drop channels can be output from each local port, with optical drop channel means for feeding all or selected optical channe

Abstract: The invention pertains to optical fiber transmission systems, and is particularly relevant to transmission of large volumes of data over long distances at high rates. An improved apparatus and method for measuring dispersion in a fiber span is disclosed. In particular, the invention teaches a highly accurate technique for measuring the fiber dispersion at a single wavelength. Transmitter and receiver structure and data processing algorithms are disclosed. An improved apparatus and method for measuring dispersion in a fiber span. In particular, the invention teaches a highly accurate technique for measuring the fiber dispersion at a single wavelength. Transmitter and receiver structure and data processing algorithms are disclosed.

Abstract: Dispersion compensation is provided in an optical transmission system. An optical line couples first and second transceivers, and a plurality of amplifiers coupled to the optical line are spaced throughout the optical line with variable span distances. A plurality of dispersion compensation modules include a coarse granularity fiber, a connector, and a fine granularity fiber. A memory is associated with the dispersion compensators to provide information related to the value of the dispersion compensation.

Abstract: A method and apparatus for adjusting the tilt of an inline amplifier. A controller reads the power of an amplifier twice. Then, if there is a change in power, a difference is calculated by subtracting the first power from the second power. A tilt correction is calculated by multiplying the change in power by a negative constant. The system then adjusts a gain control device by the tilt correction. Because of the simplicity of the algorithm and location of the controller, adjustments can be made to the gain tilt within approximately 100 ?s and system failures cam be avoided.

Abstract: The invention pertains to optical fiber transmission systems, and is particularly relevant to optical transport systems employing Raman optical amplifiers. In particular the invention teaches an apparatus and method to provide initial tuning of a Raman pump module. In the present invention, improvements to Raman gain control are taught in order to provide for an advantageous Raman gain spectral profile.

Abstract: A method and apparatus for adjusting the tilt of an inline amplifier. A controller reads the power of an amplifier twice. Then, if there is a change in power, a difference is calculated by subtracting the first power from the second power. A tilt correction is calculated by multiplying the change in power by a negative constant. The system then adjusts a gain control device by the tilt correction. Because of the simplicity of the algorithm and location of the controller, adjustments can be made to the gain tilt within approximately 100 ?s and system failures can be avoided.

Abstract: An automated optical transport system is provided which provides for automatic discovery of system components, automatic inventory of system components, automatic topology detection, automatic provisioning of channels, and automatic characterization and tuning of system components and fiber. The invention provides automation capability through inclusion of management card capabilities at each station which communicates through a reverse propagating service channel. Dynamic and propagation direction independent segments are provided in conjunction with a token-based scheme to repeatedly tune, update and monitor the transport system.

Abstract: The invention pertains to optical fiber transmission systems, and is particularly relevant to transmission of large volumes of data over long distances at high rates. An improved apparatus achieving precise dispersion compensation in a fiber span is disclosed. In particular, the invention teaches a configurable dispersion compensation trimmer with automatic detection of configuration.