319 results about "Raman amplifiers" patented technology

A modular, compact and widely tunable laser system for the efficient generation of high peak and high average power ultrashort pulses. Modularity is ensured by the implementation of interchangeable amplifier components. System compactness is ensured by employing efficient fiber amplifiers, directly or indirectly pumped by diode lasers. Peak power handling capability of the fiber amplifiers is expanded by using optimized pulse shapes, as well as dispersively broadened pulses. Dispersive broadening is introduced by dispersive pulse stretching in the presence of self-phase modulation and gain, resulting in the formation of high-power parabolic pulses. In addition, dispersive broadening is also introduced by simple fiber delay lines or chirped fiber gratings, resulting in a further increase of the energy handling ability of the fiber amplifiers. The phase of the pulses in the dispersive delay line is controlled to quartic order by the use of fibers with varying amounts of waveguide dispersion or by controlling the chirp of the fiber gratings. After amplification, the dispersively stretched pulses can be re-compressed to nearly their bandwidth limit by the implementation of another set of dispersive delay lines. To ensure a wide tunability of the whole system, Raman-shifting of the compact sources of ultrashort pulses in conjunction with frequency-conversion in nonlinear optical crystals can be implemented, or an Anti-Stokes fiber in conjunction with fiber amplifiers and Raman-shifters are used. A particularly compact implementation of the whole system uses fiber oscillators in conjunction with fiber amplifiers. Additionally, long, distributed, positive dispersion optical amplifiers are used to improve transmission characteristics of an optical communication system. Finally, an optical communication system utilizes a Raman amplifier fiber pumped by a train of Raman-shifted, wavelength-tunable pump pulses, to thereby amplify an optical signal which counterpropogates within the Raman amplifier fiber with respect to the pump pulses.

A method and apparatus for enabling multiple optical line termination (OLT) devices to share a feeder fiber are disclosed. For example, the optical network comprises a plurality of optical line termination (OLT) devices, where each OLT device having a transceiver for sending and receiving optical signals. The optical network further comprises a wave division multiplexer (WDM) combiner, coupled to the plurality of OLT devices, for combining optical signals received from the plurality of OLT devices. The optical network further comprises an optical extender box comprising at least one hybrid SOA-Raman amplifier, wherein the optical extender box is coupled to the WDM combiner via a first standard single mode fiber section. Finally, the optical network further comprises at least one optical splitter coupled to the optical extender box via a second standard single mode fiber section.

Apparatus and method for gain measurement and control of a Distributed Raman Amplifier (DRA). Various embodiments of the apparatus include a detection unit operative to measure, during operation of the DRA, the optical power of a filtered component of the light entering the DRA from the transmission fiber and a gain calculation and control unit coupled to the detection unit and operative to calculate a signal Raman gain property from the measured optical power. The filtered component may exemplarily be a result of passing the light through a band pass filter, a spectral filter with a given spectral shape or a notch filter. The signal Raman gain property may be an average on-off signal Raman gain, an average net signal Raman gain or a signal Raman gain tilt within a communication band. The apparatus and method may be used to operate the DRA in Automatic Gain Control, i.e. to maintain a required constant signal Raman gain and / or signal Raman gain tilt.

An optical fiber propagates and amplifies a second signal light that is a wavelength-multiplexed signal of a first signal light of a plurality of wavelengths and a reference light that is out of a wavelength range of amplification. An excitation light source outputs an excitation light for amplifying the second signal light. A beam splitter splits a portion of the second signal light into the first signal light and the reference light. A signal light level detecting unit detects a level of the first signal light. A reference light level detecting unit detects a level of the reference light. A signal level setting unit calculates a target value for constantly maintaining a Raman gain, and controls the output level of the excitation light in such a way that the first signal level matches with the target value.