Abstract: A system is provided for generating a laser beam via non-linear effects, including: a monofrequency continuous-wave laser source; and an external resonant cavity referred to as a microchip cavity. The microchip cavity is composite insofar as it is a unitary assembly of a plurality of materials g: at least one nonlinear crystal; an entrance mirror; a concave mirror deposited on a material fixed to the nonlinear crystal—the material on which the concave mirror is deposited is different from the constituent material of the nonlinear crystal; a first thermoelectric module for controlling the temperature of the nonlinear crystal; and at least one second thermoelectric module for controlling at least the temperature of the material on which the concave mirror is deposited.

Abstract: A system is provided for generating a laser beam via non-linear effects, including: a monofrequency continuous-wave laser source; and an external resonant cavity referred to as a microchip cavity. The microchip cavity is composite insofar as it is a unitary assembly of a plurality of materials g: at least one nonlinear crystal; an entrance mirror; a concave mirror deposited on a material fixed to the nonlinear crystal—the material on which the concave mirror is deposited is different from the constituent material of the nonlinear crystal; a first thermoelectric module for controlling the temperature of the nonlinear crystal; and at least one second thermoelectric module for controlling at least the temperature of the material on which the concave mirror is deposited.

Abstract: A Raman laser device includes: an amplifying medium (2) absorbent at a pump wavelength ?P and emitting at an excitation wavelength ?S, a Raman medium (3) exhibiting at least one Stokes shift ??R, such as to convert the emission at the excitation wavelength ?S into a continuous emission at a Raman wavelength ?R. The amplifying medium and the Raman medium belong to a Raman cavity resonant at the excitation wavelength ?S and at the Raman wavelength ?R. The length of the Raman medium is less than 9 mm and the sum of the gaps between each of the elements of the Raman cavity is less than 2 mm. A system including such a Raman laser device, and a method of adjusting the Raman laser device are described.

Abstract: A continuous laser device including: an amplifying element, at least two birefringent filters or intracavity Lyot filters allowing a single-frequency laser emission; these two Lyot filters being constituted by a polarizing element sandwiched between two birefringent elements; the first Lyot filter having a Free Spectral Range value FSR1 substantially equal to the laser emission bandwidth of the amplifying element; and the second Lyot filter having a Free Spectral Range value FSR2 different from FSR1.

Abstract: A laser device includes: an amplifying medium (1, 7) adapted to generate a fundamental wavelength laser beam (13); a birefringent non-linear medium (3, 20, 20) for doubling the fundamental wavelength laser beam to generate a harmonic wavelength laser beam (14); a polarizing medium (1b, 5, 6, 2, 8, 9, 16, 20) for selecting a fundamental wavelength laser beam polarization, the polarizing medium being such that the fundamental wave at its output remains parallel to the fundamental wave at its input. The invention is characterized in that the polarizing medium (1b, 5, 6, 2, 8, 9, 16, 20) has an output side (2b) perpendicular to the fundamental wave exiting the polarizing medium. The amplifying medium, the birefringent non-linear medium are mutually integral so as to constitute a monolithic resonant cavity.

Abstract: A diode-pumped intra-cavity frequency-tripled continuous laser device, this device includes: an amplifying medium, a birefringent non-linear medium for frequency doubling, a birefringent non-linear medium for frequency tripling; and a polarizing medium arranged so as to constitute an intra-cavity birefringent filter or Lyot filter, the Lyot filter being adapted to allow monofrequency output emission from the laser device.

Abstract: An intracavity-doubled laser device, includes a pumping laser-diode, a Nd:YAG amplifying medium stimulated by a laser beam with a fundamental wavelength emitted by the laser diode, the output face of the amplifying medium being cut at the Brewster angle for the fundamental wavelength and a birefringent frequency-doubling KNbO3 crystal. The device further includes an isotropic medium (3), inserted between the input face (8) of the birefringent crystal, the amplifying medium (2) and the birefringent crystal (4), being fixed to each other such as to provide a monolithic resonant cavity. Furthermore, the crystal axis “c” of the birefringent crystal includes a non-zero angle <c with relation to the orthogonal direction of polarization of the fundamental wave defined by the Brewster surface.

Abstract: A laser device includes: an amplifying medium (1, 7) adapted to generate a fundamental wavelength laser beam (13); a birefringent non-linear medium (3, 20, 20) for doubling the fundamental wavelength laser beam to generate a harmonic wavelength laser beam (14); a polarizing medium (1b, 5, 6, 2, 8, 9, 16, 20) for selecting a fundamental wavelength laser beam polarization, the polarizing medium being such that the fundamental wave at its output remains parallel to the fundamental wave at its input. The invention is characterized in that the polarizing medium (1b, 5, 6, 2, 8, 9, 16, 20) has an output side (2b) perpendicular to the fundamental wave exiting the polarizing medium. The amplifying medium, the birefringent non-linear medium are mutually integral so as to constitute a monolithic resonant cavity.

Abstract: A laser device including: a first amplifying medium capable of emitting a first output laser beam at the output wavelength ?s; and a second amplifying medium capable of emitting a second laser beam of intermediate wavelength ?i and capable of being pumped at a pump wavelength ?p such that ?i is included between ?p and ?s; wherein a single laser cavity containing said first and second amplifying media, this cavity being closed by two mirrors with maximum reflection at the wavelength ?i, and in that there are two distinct laser wavelengths ?i and ?s which take place in said cavity.

Abstract: The invention concerns a laser device (1, 13) comprising: a three-level amplifying medium (3) adapted to emit a first laser beam (3) of fundamental wavelength; a four-level amplifying medium (5) adapted to emit a second laser beam (7) of fundamental wavelength; a non-linear crystal (4) adapted to mix the first and second beams and to generate a third beam (14, 15) whereof the frequency is the sum of the frequencies of said first and second laser beams. Said device is characterized in that the three-level amplifying medium (3) and at least the non-linear crystal (4) form a resonant cavity for the first laser beam (6), and the four-level amplifying medium (5) and at least the non-linear crystal (4) form a resonant cavity for the second laser beam (7), the two amplifying media and the non-linear crystal forming a linear cavity.

Abstract: The invention relates to an intracavity-doubled laser device, comprising a pumping laser-diode, a Nd:YAG amplifying medium stimulated by a laser beam with a fundamental wavelength emitted by the laser diode, the output face of said amplifying medium being cut at the Brewster angle for said fundamental wavelength and a birefringent frequency-doubling KNbO3 crystal. The device further comprises an isotropic medium (3), inserted between the input face (8) of the birefringent crystal, the amplifying medium (2) and the birefringent crystal (4), being fixed to each other such as to provide a monolithic resonant cavity. Furthermore, the crystal axis “c” of the birefringent crystal includes a non-zero angle <c with relation to the orthogonal direction of polarisation of the fundamental wave defined by the Brewster surface.

Abstract: Adjusting power for a WDM optical transmission system comprising emitter means, an optical transmission line, and receiver means, the method being characterized in that for each wavelength channel, the power emitted for said channel by the emitter means is adjusted as a function of the optical powers received for said channel at a plurality of points distributed along the transmission line.

Abstract: An optical fiber transmission system using RZ pulses and having emitter means, receiver means, and a transmission line which extends between said emitter means and receiver means, the emitter and receiver means implementing wavelength division multiplexing, the transmission line comprising a plurality of main optical fiber sections presenting dispersion of a given type with dispersion-compensating means being interposed therebetween, the system being characterized in that the dispersion compensation implemented by said means is such that the spectrum width of pulses at the outlet from said means is constant over the length of the transmission line.

Abstract: The invention concerns a transmission system, in particular ground-based, by optical fibre with RZ pulses comprising transmitting means, receiving means, the transmitting and receiving means using wavelength multiplexing, the transmission line comprising a plurality of main optical fibre sections having a dispersion of a given type between which are interposed dispersion-compensating means. The compensation of the dispersion operated by said means is such that the width of the spectrum of the pulses in output of said means is constant over the transmission line. The RZ pulses are of a duration ranging between 40 and 80 ps. The different channels have a rate of the order of 10 G/bits or more. Their frequency spacing is of the order of 25 GHz or less.

Abstract: A method of adjusting power for a WDM optical transmission system comprising emitter means, an optical transmission line, and receiver means, the method being characterized in that for each wavelength channel, the power emitted for said channel by the emitter means is adjusted as a function of the optical powers received for said channel at a plurality of points distributed along the transmission line.

Abstract: A long-distance optical transmission system comprising pulse emitter and receiver means (1, 2) and an optical line (3) which extends between said emitter and receiver means (1, 2) and which comprises alternating segments (3a, 3b) of dispersive fibers having chromatic dispersion of opposite signs, and also having a plurality of amplifiers (4), the system being characterized in that the optical line (3) comprises a plurality of pairs of dispersive fiber segments (3a, 3b) having chromatic is dispersion of opposite signs between successive amplifiers (4), and in that the cumulative dispersion C over the majority of the segments of the optical line satisfies the relationship (R)|C|&Dgr;&ngr;2<0.3 where C is expressed in ps/nm and where &Dgr;&ngr; is the half-height spectral value of the pulses expressed in Thz.

Abstract: A long-distance optical transmission system comprising pulse emitter and receiver means (1, 2) and an optical line (3) which extends between said emitter and receiver means (1, 2) and which comprises alternating segments (3a, 3b) of dispersive fibers having chromatic dispersion of opposite signs, and also having a plurality of amplifiers (4), the system being characterized in that the optical line (3) comprises a plurality of pairs of dispersive fiber segments (3a, 3b) having chromatic dispersion of opposite signs between successive amplifiers (4), and in that the cumulative dispersion C over the majority of the segments of the optical line satisfies the relationship