Abstract: Good femtosecond fiber laser performance is achieved by producing picosecond Raman shifted pulses of sufficient intensity to undergo self-phase modulation (SPM), thus causing the pulses to advantageously spread spectrally, which then makes it possible to temporally compress the pulses with an optical compressor to produce femtosecond pulses with high peak power.

Abstract: There is provided a system for remote pumping of a Raman fiber amplifier comprising a pump laser located remotely from the Raman fiber amplifier and a laserhead and one or more optical fibers to optically couple the high power pump light from the remote pump laser to the Raman fiber amplifier where a seed laser light is amplified wherein the pump laser for producing a high power laser light of a predetermined pump wavelength comprises a first fiber laser emitting light at the predetermined pump wavelength and one (second) or two (third) laser emitting light at a wavelength lower than the predetermined pump wavelength and multiplexed with light from the first laser into an optical fiber providing Raman gain at the predetermined pump wavelength to convert the second (and optionally also the third) laser light to light at the predetermined pump wavelength.

Abstract: There is provided a system for remote pumping of a Raman fiber amplifier comprising a pump laser located remotely from the Raman fiber amplifier and a laserhead and one or more optical fibers to optically couple the high power pump light from the remote pump laser to the Raman fiber amplifier where a seed laser light is amplified wherein the pump laser for producing a high power laser light of a predetermined pump wavelength comprises a first fiber laser emitting light at the predetermined pump wavelength and one (second) or two (third) laser emitting light at a wavelength lower than the predetermined pump wavelength and multiplexed with light from the first laser into an optical fiber providing Raman gain at the predetermined pump wavelength to convert the second (and optionally also the third) laser light to light at the predetermined pump wavelength.

Abstract: A method for pumping remote optically-pumped fiber amplifiers (ROPAs) in fiber-optic telecommunication systems is disclosed which uses cascaded Raman amplification to increase the maximum amount of pump power that can be delivered to the ROPA. According to the prior art, high power at the ROPA pump wavelength, ?p, is launched directly into the fiber and the maximum launch power is limited by the onset of pump depletion by Raman noise and oscillations due to the high Raman gain at ˜(?p+100) nm. In preferred embodiments of the present invention, a ‘primary’ pump source of wavelength shorter than ?p is launched into the delivery fiber along with two or more significantly lower-power ‘seed’ sources, among which is included one at ?p. The wavelength and power of the seed source(s) are chosen such that, when combined with the high-power primary source, a series, n, where n?2, of Raman conversions within the fiber ultimately leads to the development of high power at ?p.

Abstract: A method for pumping remote optically-pumped fiber amplifiers (ROPAs) in fiber-optic telecommunication systems is disclosed which uses cascaded Raman amplification to increase the maximum amount of pump power that can be delivered to the ROPA. According to the prior art, high power at the ROPA pump wavelength, ?p, is launched directly into the fiber and the maximum launch power is limited by the onset of pump depletion by Raman noise and oscillations due to the high Raman gain at ˜(?p+100) nm. In preferred embodiments of the present invention, a ‘primary’ pump source of wavelength shorter than ?p is launched into the delivery fiber along with two or more significantly lower-power ‘seed’ sources, among which is included one at ?p. The wavelength and power of the seed source(s) are chosen such that, when combined with the high-power primary source, a series, n, where n?2, of Raman conversions within the fiber ultimately leads to the development of high power at ?p.

Abstract: A pumping scheme for distributed Raman amplification (DRA) in optical fiber telecommunication systems is disclosed in which pump energy at the wavelength(s) required for DRA of the transmitted optical signal(s) is developed within the transmission fiber through a series, n, where n≧1, of Raman conversions. In preferred embodiments, a ‘primary’ pump source of wavelength shorter than the ultimately desired pump wavelength(s) is launched into the fiber along with one or more significantly lower-power secondary ‘seed’ sources. The wavelength and power of the secondary source(s) are chosen such that, when combined with the high-power primary source, Raman conversions within the fiber ultimately lead to the development of high power at the desired pump wavelength(s).

Abstract: A pumping scheme for distributed Raman amplification (DRA) in optical fiber telecommunication systems is disclosed in which pump energy at the wavelength(s) required for DRA of the transmitted optical signal(s) is developed within the transmission fiber through a series, n, where n≧1, of Raman conversions. In preferred embodiments, a ‘primary’ pump source of wavelength shorter than the ultimately desired pump wavelength(s) is launched into the fiber along with one or more significantly lower-power secondary ‘seed’ sources. The wavelength and power of the secondary source(s) are chosen such that, when combined with the high-power primary source, Raman conversions within the fiber ultimately lead to the development of high power at the desired pump wavelength(s).

Abstract: A plant for electroslag remelting of metals and alloys, comprising a cooled mould mounted on a cooled base plate where a slag bath is arranged. Introduced into said slag bath is one end of a consumable electrode, its other end being connected to one of the poles of a current supply source. The plant has at least one non-consumable electrode that is connected to the other pole of the current supply source in series with the consumable electrode. A method of electroslag remelting of metals and alloys in which an electric current is passed through the consumable electrode the slag bath and the non-consumable electrode during the remelting process.