Abstract: An optical amplifier includes at least one pump source and an optical fiber cable which includes an amplifying optical fiber and a pump optical fiber that are defined by respective lengths. The amplifying optical fiber and the pump optical fiber are coated with a common coating along a portion of their respective lengths, and the fibers are in optical contact with each other along a coating length within the common coating. The common coating has a refractive index which is lower than a refractive index of a cladding material of the pump optical fiber. The fibers are made substantially from glass. The amplifying optical fiber includes a core and a cladding, and is doped with a rare earth dopant. The pump optical fiber is defined by a first end and a second end, the first end of the pump optical fiber being connected to the pump source.

Abstract: An optical amplifier includes at least one pump source and an optical fibre cable which includes an amplifying optical fibre and a pump optical fibre that are defined by respective lengths. The amplifying optical fibre and the pump optical fibre are coated with a common coating along a portion of their respective lengths, and the fibres are in optical contact with each other along a coating length within the common coating. The common coating has a refractive index which is lower than a refractive index of a cladding material of the pump optical fibre. The fibres are made substantially from glass. The amplifying optical fibre includes a core and a cladding, and is doped with a rare earth dopant. The pump optical fibre is defined by a first end and a second end, the first end of the pump optical fibre being connected to the pump source.

Abstract: An optical fiber arrangement has at least two optical fiber sections, each optical fiber section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fiber arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fiber. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fiber and a first multiplexer connected to the input fiber. Each amplifier is configured such that at least one of the amplifying optical fibers is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: An optical fibre arrangement has at least two optical fibre sections, each optical fibre section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fibre arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fibre. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fibre and a first multiplexer connected to the input fibre. Each amplifier is configured such that at least one of the amplifying optical fibres is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: An optical fiber arrangement has at least two optical fiber sections, each optical fiber section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fiber arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fiber. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fiber and a first multiplexer connected to the input fiber. Each amplifier is configured such that at least one of the amplifying optical fibers is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: Apparatus for providing optical radiation includes a pump source and at least one first amplifying waveguide. The first amplifying waveguide emits optical radiation in excess of 1400 nm when pumped by the pump source. In one embodiment, the pump source can include a plurality of laser diodes and a plurality of second amplifying waveguides. In this arrangement the first amplifying waveguide is pumped by the second amplifying waveguides, the second amplifying waveguides are pumped by the laser diodes, and the second amplifying waveguides are configured to improve the beam quality of radiation emitted by the laser diodes.

Abstract: An optical fibre arrangement has at least two optical fibre sections, each optical fibre section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fibre arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fibre. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fibre and a first multiplexer connected to the input fibre. Each amplifier is configured such that at least one of the amplifying optical fibres is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: A source of pulses of coherent radiation at a wavelength of approximately 1 ?m, comprises a pump source for producing pump light; a laser cavity comprising an Yb3+-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

Abstract: An optical fiber arrangement has at least two optical fiber sections, each optical fiber section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fiber arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fiber. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fiber and a first multiplexer connected to the input fiber. Each amplifier is configured such that at least one of the amplifying optical fibers is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: A source of pulses of coherent radiation at a wavelength of approximately 1 ?m, comprises a pump source for producing pump light, a laser cavity comprising an Yb3+-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

Abstract: An optical fibre arrangement has at least two optical fibre sections, each optical fibre section defining an outside longitudinally extending surface. The outside longitudinally extending surfaces are in optical contact with each other. The invention further provides for an amplifying optical device have an optical fibre arrangement as just described, and a pump source. The amplifying optical device is configured such that the pump source illuminates the amplifying optical fibre. A amplifying arrangement is also disclosed. The amplifying arrangement includes a plurality of amplifying optical devices as just described, and each amplifier also has at least one input fibre and a first multiplexer connected to the input fibre. Each amplifier is configured such that at least one of the amplifying optical fibres is connected to the first multiplexer. The amplifying arrangement also has a second multiplexer connected to each of the first multiplexers.

Abstract: A source of pulses of coherent radiation at a wavelength of approximately 1 &mgr;m, comprises a pump source for producing pump light; a laser cavity comprising an Yb3+-doped gain medium arranged to receive the pump light, the laser cavity being modelocked to generate laser pulses at a defined repetition rate; a pulse detector arranged to generate a pulse selection signal indicative of the repetition rate; a pulse selector arranged to reduce the repetition rate of the laser pulses responsive to the pulse selection signal from the pulse detector by passing only selected ones of the laser pulses; and at least one optical amplifier for amplifying the laser pulses of reduced repetition rate. The at least one optical amplifier can be configured for chirped or parabolic pulse amplification.

Abstract: Single- or few-moded waveguiding cladding-pumped lasers, superfluorescent sources, and amplifiers, as well as lasers, including those for high-energy pulses, are disclosed, in which the interaction between the waveguided light and a gain medium is substantially reduced. This leads to decreased losses of guided desired light as well as to decreased losses through emission of undesired light, compared to devices of the prior art. Furthermore, cross-talk and inter-symbol interference in semiconductor amplifiers can be reduced. We also disclose devices with a predetermined saturation power. As a preferred embodiment of the invention, we disclose a single (transverse) mode optical fiber laser or amplifier in which the active medium (providing gain or saturable absorption) is shaped as a ring, situated in a region of the fiber's cross-section where the intensity of the signal light is substantially reduced compared to its peak value. The fiber can be cladding-pumped.

Abstract: An optical fiber amplifier including a first optical fiber doped with erbium and phosphorous, for amplifying signal light excited by the erbium, a second optical fiber connected to one end of the first optical fiber, doped with erbium and aluminum, and having a gain spectrum slope opposite to the first optical fiber according to population inversion of the erbium, for amplifying signal light output by the first optical fiber, a pumping laser source connected to another end of the first optical fiber, for exciting the erbium of the first and second optical fibers, and a light coupler for coupling pumping light from the pumping laser source to the signal light and outputting the resultant light to the first optical fiber. Two types of EDFs (erbium doped fibers) having different gain spectrums are used, such that the gain spectrum of each of the EDFs actively varies with the input signal light power or pumping light power. Thus, an entirely flat gain is kept.

Abstract: Single- or few-moded waveguiding cladding-pumped lasers, superfluorescent sources, and amplifiers, as well as lasers, including those for high-energy pulses, are discloswed, in which the interaction between the waveguided light and a gain medium is substantially reduced. This leads to decreased losses of guided desired light as well as to decreased losses through emission of undesired light, compared to devices of the prior art. Furthermore, cross-talk and inter-symbol interference in semiconductor amplifiers can be reduced. We also disclose devices with a predetermined saturation power.

Abstract: Single- or few-moded waveguiding cladding-pumped lasers, superfluorescent sources, and amplifiers, as well as lasers, including those for high-energy pulses, are disclosed, in which the interaction between the waveguided light and a gain medium is substantially reduced. This leads to decreased losses of guided desired light as well as to decreased losses through emission of undesired light, compared to devices of the prior art. Furthermore, cross-talk and inter-symbol interference in semiconductor amplifiers can be reduced. We also disclose devices with a predetermined saturation power. As a preferred embodiment of the invention, we disclose a single (transverse) mode optical fiber laser or amplifier in which the active medium (providing gain or saturable absorption) is shaped as a ring, situated in a region of the fiber' cross-section where the intensity of the signal light is substantially reduced compared to its peak value. The fiber can be cladding-pumped.

Abstract: An erbium doped fiber amplifier (EDFA) suitable for amplifying a long wavelength light signal in the range in the 1570 to 1610 nm band, includes a pump light source for generating pump light in the 980 or 1480 nm band, a light coupler for receiving the pump light from the pump light source and coupling the same to the received light signal, first and second optical fibers doped with erbium ions, for amplifying the received light signal by the pump light, and an isolator positioned at a point between the first and second erbium doped optical fibers (EDFs). The gain and noise figure of the EDFA for amplifying received light signal in a long wavelength band can be improved. Also, an EDFA suitable for amplifying received light signal in the 1570 to 1610 nm band can be attained.

Abstract: An optical amplifier including a pumping optical source, a plurality of erbium doped optical fibers for amplifying optical signals of a plurality of wavelengths using pumping light generated by the pumping optical source, and a plurality of gratings alternately connected to the optical fibers, for reflecting an optical signal of a specific wavelength among different wavelength optical signals amplified by the optical fibers, wherein when optical signals for channels have different powers, the optical signal power for each individual channel is equalized by amplifying and reflecting the optical signals at different positions with different amplification gains. Accordingly, in a system having a great loss such as long-distance transmission, optical signals of different wavelengths are reflected at different positions, and amplified by a gain medium, thus making power equalization possible.

Abstract: A high power pumping apparatus for optical fiber amplification includes: a pumping portion for generating pumping light of a predetermined wavelength band, the wavelength of which is determined by the wavelength of the pumping light fed back from a subsegment portion; a wavelength division multiplexer for multiplexing the pumping light generated by the pumping portion, for dividing the signal light incident from a subsegment portion according to wavelengths, and for outputting the signal light to the pumping portion; and a broad-band reflecting portion for reflecting some of the output light multiplexed by the wavelength division multiplexer, for outputting the reflected light to the wavelength division multiplexer, and for outputting the remaining light as pumping light for light amplification. In the high power pumping apparatus according to the present invention, the same pumping diodes can be used without a wavelength selecting diode.

Abstract: A multiwavelength, multistage optical amplifier, which can be arranged in a cascade, substantially increases the degree of automatic power control (APC), multiwavelength APC (MAPC), and multiwavelength automatic gain control (MAGC), for at least two wavelengths. The multiwavelength, multistage optical amplifier or amplifier cascade has at least two spectrally different gain media (GM), i.e. first and second GM, connected in series for amplifying a signal having at least two wavelengths, i.e. first and second wavelengths. The first GM may be aluminosilicate erbium doped fiber, the second GM may be germanosilicate erbium doped optical fiber. The gain at the first wavelength is smaller than the gain at the second wavelength, while the signal power at the first wavelength is larger than the signal power at the second one, and vice versa. This may automatically compensate for loss tilt. The gain media may be homogeneously broadened.