Abstract: The invention is related to a waveguide amplifier with an input for optical signals and an output for optical signals with at least one piece of amplifying waveguide with at least one mean for coupling pump laser modules to the amplifying waveguide which contains Tm ions. The invention is also related to a pumping scheme for waveguide amplifier feeding two different wavelengths in to the waveguide.

Abstract: A spatial light modulator (SLM) is made up of a cell filled with a liquid crystal (LC) based substance. Latter has a variable scattering property with respect to an electric field present in the cell. By using a plurality of electrodes in the direct vicinity of said cell, it is then possible to build an electric field inside it which will permit advantageously to modulate a continuous spectrum from optical signals transmitted through said cell. The different pass bands present in said continuous spectrum while at least few of them comprise at least a respective different wavelength will have to be transmitted through said cell at different regions. Latter will correspond to different values of the amplitude of scattering such to be adapted to modulate the respective different pass bands. Such SLM is used to build a dynamic spectral equalizer. Latter contains a spectral dispersive element placed on an optical path of an incident light beam.

Abstract: The invention relates to an optical fiber amplifier (OFA) having a controllable heating system for adjusting and stabilizing the temperature of a fiber, wherein the heating system comprises a heat-generating fiber coating (TC) that has an electrical connection for applying a heating voltage or injecting a heating current (I1, I2) for the purpose of heat generation, wherein the heat-generating fiber coating (TC) surrounds at least a part of the fiber (OF), and also a method therefor.

Abstract: A C-band optical amplifier includes a fiber with a monomode core, a multimode internal cladding and an external cladding. It further includes a pump for pumping the fiber. The fiber is not doped with ytterbium and the multimode cladding has a diameter less than 55 &mgr;m. The amplifier can be used for amplifying C-band signals in wavelength division multiplex transmission systems.

Abstract: An optical fiber amplifier is proposed comprising at least one pump light source (3), at least one amplifying fiber section (10), and at least one coupler (8) which establishes a connection between the input fiber (1) of the fiber type I, the pump light source (3), the amplifying fiber section (10), and the output fiber (12) of the fiber type I. The amplifying fiber section (10) consists of a fiber type II, and the splices (2, 11) between the fiber type I and the fiber type II are arranged relative to the amplifying fiber section (10) such that light propagated in the direction opposite to the signal direction and light propagated in the signal direction passes through means absorbent of short wavelengths before it reaches the splices.

Abstract: The invention relates to optical fiber apparatus comprising an amplifier having optimal gain excursion over a given wavelength band for given input power, and a filter having a bell-shaped transfer function, with the center wavelength of the filter being tunable over a range that is sufficient to enable the gain excursion of the amplifier over said wavelength band to be reduced when the power received by the amplifier is different from said given input power. The invention makes it possible to match amplifier apparatuses to line losses while minimizing overall loss.

Abstract: The gain of a constant passband variable gain optical amplifier is adjusted by a gain control signal (9G) that can take m discrete values. In one embodiment it includes m amplifiers (G.sub.1, . . . , G.sub.m) each having a fixed gain different from the gains of the other amplifiers and a passband identical to that of the others; an optical switch (SW1) having an input (E) coupled to the input (EA) of the variable amplifier (AGV1), m outputs (S.sub.1, . . . , S.sub.m) respectively coupled to the inputs of the m fixed gain amplifiers (G.sub.1, . . . , G.sub.m) and a control input receiving the gain control signal (G); and an optical switch (SW2) having m inputs (E.sub.1, . . . , E.sub.m) respectively coupled to the outputs of the m fixed gain amplifiers (G.sub.1, . . . , G.sub.m), an output (SC) coupled to the output (SA) of the variable gain amplifier (AGV1) and a control input receiving the gain control signal (G). The invention is particularly applicable to long-haul optical links and spectral multiplexing.

Abstract: The invention relates to a system for distributing amplified optical signals, the system comprising an optical star coupler having at least two inputs, each input of said coupler being connected to the output of a respective optical amplifier whose input receives an optical signal. According to the invention, said optical amplifiers are optical amplifiers whose gains are kept constant.

Abstract: A method for equalizing power levels of channels of an optical frequency division multiplexed signal determines the power level of each channel of the optical frequency division multiplexed signal and introduces attenuation into the channels having high power levels corresponding to the difference between a level deduced from these high levels and a low reference level. The equalization system includes at least one optical equalizer module which measures the optical power levels of the channels of the signal to be monitored, a processor for implementing the method and variable attenuators controlled by the processor and operating separately on the power levels of the channels.

Abstract: A link using spectrum multiplexing, in which link an amplifying fiber amplifies a plurality of multiplexed carrier waves. The invention makes it possible to maintain a flat spectrum distribution of the gain of the amplifying fiber when the number of carrier waves varies. For that purpose, light that is amplified by the amplifying fiber and that is independent of the carrier waves is servo-controlled in power. The light is constituted by a reverse amplified spontaneous emission. After being filtered in a filter and detected by a photodiode, the light controls the power supplied to two laser diodes for pumping the fiber. The invention applies in particular to implementing optical transmission networks.

Abstract: An amplifying optical fiber amplifies a plurality of wavelength-multiplexed carrier waves. The invention enables the gain as seen by each of the carrier waves to be maintained, in particular when the total input power varies. For that purpose, amplified spontaneous "reverse" emission light is servo-controlled in power. After being filtered in a filter and detected by a photodiode, said light controls the powering current supplied to two laser diodes for pumping the fiber. The invention applies in particular to implementing optical transmission networks.