Abstract: A device for non-linear conversion of first infrared signal into a second infrared signal with a wavelength that is less than that of the first infrared signal by means of four-wave mixing, which includes at least one portion of SiGe arranged on at least one first layer of material with a refractive index which is less than that of silicon, a germanium concentration in the portion of SiGe which varies continuously between a first value and a second value which is greater than the first value, in a direction which is approximately perpendicular to a face of the first layer on which the portion of SiGe is arranged, and in which a summital part of the portion of SiGe where the germanium concentration is equal to the second value is in contact with a gas and/or a material with a refractive index which is less than that of the silicon.

Abstract: A device for non-linear conversion of first infrared signal into a second infrared signal with a wavelength that is less than that of the first infrared signal by means of four-wave mixing, which includes at least one portion of SiGe arranged on at least one first layer of material with a refractive index which is less than that of silicon, a germanium concentration in the portion of SiGe which varies continuously between a first value and a second value which is greater than the first value, in a direction which is approximately perpendicular to a face of the first layer on which the portion of SiGe is arranged, and in which a summital part of the portion of SiGe where the germanium concentration is equal to the second value is in contact with a gas and/or a material with a refractive index which is less than that of the silicon.

Abstract: The invention provides a system for use in an optical communication network to reduce noise comprising means for tapping a low noise signal from said network and a phase sensitive amplifier (PSA) for conditioning said tapped signal by means for removing modulation of the tapped signal to allow for phase locking of the tapped signal. A laser source provides phase locked reference signals to generate at least one pump signal, wherein the at least one pump signal provides correct phase alignment for optimum PSA operation. The invention makes use of injection locked and/or phase locked laser sources in conjunction with low power input tap couplers, or post/mid amplification taps to provide the required phase locked reference signals without degrading the input loss or noise. The use of injection/phase locked local lasers suppresses the detrimental impact of the low tapped power or added noise in the generation of the required pump signals.