Abstract: An optical transmission system uses as its transmission medium a fiber having chromatic dispersion. A sender emits an optical signal to be transmitted into the fiber. A sender emits into the transmission medium pumping light constituting a first pump adapted to pump the optical signal by the Raman effect and pumping light constituting a second pump adapted to pump the first pumping light by the Raman effect. The first pump and the second pump are amplitude modulated and the envelopes of the first pump and the second pump are decorrelated in time. This decorrelation limits the efficiency of the Raman pumping of the first light by the second light on emission. Varying the decorrelation in time between the pump envelopes varies the region of the transmission system in which the signals are amplified.

Abstract: The invention refers to a safety procedure for optical fiber systems. Such systems are widely used in telecommunication to transport optical signals between a transmitter terminal and a receiver terminal. By the invented safety procedure the optical input power fed into said optical fiber system is automatically shut off or at least reduced in case of an unintended escape of light from at least one fiber. A safety interface, provided in the transmission line detects changes of the total optical output power in at least one fiber and initiates a shut-down of the input power as soon as a decrease of the total output power is detected, that exceeds a predefined value within a predefined time window. Thus the slope of the total output power is measured and evaluated rather than its absolute value.

Abstract: An optical transmission system uses as its transmission medium a fiber having chromatic dispersion. A sender emits an optical signal to be transmitted into the fiber. A sender emits into the transmission medium pumping light constituting a first pump adapted to pump the optical signal by the Raman effect and pumping light constituting a second pump adapted to pump the first pumping light by the Raman effect. The first pump and the second pump are amplitude modulated and the envelopes of the first pump and the second pump are decorrelated in time. This decorrelation limits the efficiency of the Raman pumping of the first light by the second light on emission. Varying the decorrelation in time between the pump envelopes varies the region of the transmission system in which the signals are amplified.

Abstract: The invention refers to a safety procedure for optical fiber systems. Such systems are widely used in telecommunication to transport optical signals between a transmitter terminal and a receiver terminal. By the invented safety procedure the optical input power fed into said optical fiber system is automatically shut off or at least reduced in case of an unintended escape of light from at least one fiber. A safety interface, provided in the transmission line detects changes of the total optical output power in at least one fiber and initiates a shut-down of the input power as soon as a decrease of the total output power is detected, that exceeds a predefined value within a predefined time window. Thus the slope of the total output power is measured and evaluated rather than its absolute value.

Abstract: A method of making an optical transmission system safe, the system including a transmission optical fiber and emitting an optical wanted signal, transmitting a transmitted optical signal containing the wanted optical signal and optical noise, sampling a portion of the transmitted optical signal constituting a monitoring optical signal, and analyzing the power of the monitoring optical signal to deduce, as a function of the power of the monitoring optical signal, whether the transmission optical fiber is broken. The method isolates in the monitoring optical signal a first signal containing only the noise and a second signal containing the noise and the wanted signal and compares the power of the first and second signals and to deduce that the transmission optical fiber is broken if the ratio of the power of the second signal to the power of the first signal is substantially equal to 1.

Abstract: An optical fiber transmission system between a sender and a receiver of at least two signals with different wavelengths includes a line optical fiber and a pumping system for sending a pump signal into the line fiber to amplify the signals by distributed stimulated Raman scattering over an amplification length of the fiber. Gain equalization is applied in-line over the amplification length of the fiber so that the gain of each signal is close to the gain of the most strongly amplified signal, whereby each signal is amplified with substantially the same gain.

Abstract: The invention refers to an optical fiber transmission system, comprising a transmitter terminal 10 launching an optical signal into a fiber line, which is guiding the signal to a receiver terminal on the far end of the fiber line. The signal composed of a multitude of bit-patterns at different wavelength channels within a given total bandwidth of wavelengths. In order to increase the optical power budget of the system, the fiber line consists, in its first section, of at least two branches 12a, 12b. The transmitter 10 launches a separate part of the optical signal into each one of the branches 12a, 12b. Each part of the signal is composed of a sub-multitude of the bit-patterns at neighboring wavelength channels within non-overlapping bandwidth domains.