Abstract: An inline modulator device for an optical transmission system, the device comprising: detector means suitable for detecting a portion of the signal transmitted on the line; modulator means; and a control circuit adjustable for synchronization, serving to extract the clock from the signal coming from the detector means and, on the basis of said clock, generating a modulation control signal which it applies to the modulator means, wherein the detector means and the modulator means are constituted respectively by the inlet section and the outlet section of an electro-absorbent modulator constituted by a two-section integrated component, such that said detector means and modulator means can be placed in the line in the form of a single insertion. The present invention also provides optical telecommunications systems using such an inline modulator device.

Abstract: A system for transmission of a digital signal on a transmission line with an optical on-line amplification. The transmission line is formed by a plurality of optical fiber sections and a plurality of optical amplifiers. Each of the optical amplifier is interposed between two adjacent optical fiber sections. The system includes at least one device for on-line compensation of the distortions induced in the digital signal, notably by the noise and the propagation on the transmission line. The on-line compensation device includes at least one bandpass optical filter having a passband whose value is substantially lower than that of the passband of the digital signal before transmission, and at least one saturable absorbent element that is a non-linear passive optical element having an absorption that depends decreasely on the optical power.

Abstract: In a system for the long-distance transmission of a digital signal on a fiber-optic transmission line connecting a transmitter station and a receiver station, the digital signal has rising edges and descending edges between two predetermined signal levels, respectively representing the two binary values that can be assumed by the digital signal, the transmitter station comprising: device for the amplitude modulation of the digital signal, delivering an amplitude modulated signal; device for the modification of the instantaneous optical frequency of the amplitude modulated signal, at the instants corresponding to the rising and descending edges of the digital signal.

Abstract: A system for very-long-distance transmission of a digital signal between a transmitter station and a receiver station, wherein the transmitter and receiver stations are connected by a monomode optical fiber with negative chromatic dispersion at the operating wavelength of the system, having a length of at least one thousand kilometers. The receiver station comprises device to compensate for the distortions due to the non-linear effects and to the chromatic dispersion introduced by the transmission line, the compensation device carrying out a positive chromatic dispersion of the received signal, the amplitude of the positive chromatic dispersion being a function notably of the amplitude of the negative chromatic dispersion induced by the optical fiber as well as of the mean on-line optical power of the signal transmitted on the optical fiber.

Abstract: Input and output equipment are provided for connecting first and second wideband signal transmission mediums through link equivalent to a balanced transmission line. The line can be made up of crosspoint cells includes in a wideband switching matrix, or can be a line distributed to intermediate equipments in a videocommuncation network. The input equipment includes means for separating high and low frequency signals included in the received wideband signals, means for transmitting the high frequency signals in differential mode, and means for transmitting the low frequency signals in High-Input Low-Output (HILO) mode. The output equipment includes means for taking the high and low frequency signals separately and means for summing the high and low frequency signals into wideband signals to be transmitted in the second medium.