Abstract: A Raman amplifier comprising a gain control unit adapted to control a pump power of an optical pump signal in response to at least one monitored optical feedback signal reflected back from a transmission line fiber connected to said pumped Raman amplifier.

Abstract: A Raman amplifier comprising a gain control unit adapted to control a pump power of an optical pump signal in response to at least one monitored optical feedback signal reflected back from a transmission line fiber connected to said pumped Raman amplifier.

Abstract: It is described an optical amplification device for receiving an optical input signal and transmitting an amplified optical output signal on the basis of the optical input signal comprising an optical amplifier that comprises an input and an output. An optical gain control unit is connected to the output path of the optical amplifier and the optical gain control unit is connected to the input path of the optical amplifier. The optical gain control unit is configured to control the gain of the optical output signal. Additionally, an electrical gain control unit is connected to the output path of the optical amplifier. The electrical gain control unit is also connected to the input path of the optical amplifier. The electrical gain control unit is configured to control the gain of the optical output signal. By providing both an electrical gain control unit and an optical gain control unit, a control characteristic can be improved.

Abstract: A Raman amplifier comprising a gain control unit adapted to control a pump power of an optical pump signal in response to at least one monitored optical feedback signal reflected back from a transmission line fiber connected to said pumped Raman amplifier.

Abstract: A Raman amplifier comprising a gain control unit adapted to control a pump power of an optical pump signal in response to at least one monitored optical feedback signal reflected back from a transmission line fiber connected to said pumped Raman amplifier.

Abstract: It is described an optical amplification device for receiving an optical input signal and transmitting an amplified optical output signal on the basis of the optical input signal comprising an optical amplifier that comprises an input and an output. An optical gain control unit is connected to the output path of the optical amplifier and the optical gain control unit is connected to the input path of the optical amplifier. The optical gain control unit is configured to control the gain of the optical output signal. Additionally, an electrical gain control unit is connected to the output path of the optical amplifier. The electrical gain control unit is also connected to the input path of the optical amplifier. The electrical gain control unit is configured to control the gain of the optical output signal. By providing both an electrical gain control unit and an optical gain control unit, a control characteristic can be improved.

Abstract: A resonant-periodic-gain distributed-feedback surface-emitting semiconductor laser has a resonator with an axis perpendicular to the plane of the substrate. The resonator comprises a stack of distributed feedback elements, each consisting of a spacer region and a very thin gain element positioned at an antinode of a standing wave inside the resonator at a designed wavelength. Each gain element consists of one or a group of closely spaced quantum-well layers. Each spacer, separating two adjacent gain elements, consists of two intermediate-and low-refractive-index layers, each layer of the spacer having an optical thickness approximately equal to a quarter of the designed wavelength. The refractive index of each of the gain elements is higher than that of the spacer materials. The device can be surrounded by a material of refractive index lower than all materials comprising the device for better confinement of carriers and control of guided modes of radiation.