44 results about "Fiber raman amplifier" patented technology

The invention discloses super-far distributed fiber Raman and Brillouin photon sensors; by using the stimulated Raman scattering effect of fiber, the self Raman scattering effect of fiber, the Brillouin scattering effect of fiber and the light time-field reflection principle, distributed fiber Raman photon temperature sensors, distributed fiber Brillouin photon strain sensors and distributed fiber Raman amplifier are integrated together. Fiber consumption is overcome by using the gain of amplifier, and strengths of self Raman scattering light and Brillouin scattering light in fiber is enhanced, the signal to noise ratio of the system of distributed fiber Raman photon sensor and distributed fiber Brillouin photon strain sensor is enhanced, meanwhile, the transmission distances of distributed fiber Raman photon sensor and distributed fiber Brillouin photon strain sensor are increased, finally, the temperature and stress measuring accuracy is enhanced.

A method of Raman amplification comprising the step of effecting a plurality of pump wavelengths on a Raman-active transmission medium transmitting counter-propagating signal wavelengths, wherein at least one of said pump wavelengths are interleaved between said signal wavelengths.

The present invention discloses an ultra-long-range distributed fiber Raman photon temperature sensor of an integrated Raman amplifier, and comprises a distributed fiber Raman photon temperature sensor, a distributed fiber Raman amplifier and a fiber grating narrowband reflecting filter. The distributed fiber Raman amplifier is adopted to be embedded into the distributed fiber Raman photon temperature sensor; the gain of the amplifier is used to overcome fiber loss, strengthen the intensity of spontaneous Raman scattering light in the fiber, improve signal-to-noise ratio of the distributed fiber Raman photon temperature sensor system, augment the transmission distance of the distributed fiber Raman photon temperature sensor and improve temperature-measuring precision. With the fiber stimulated Raman scattering effect, the fiber spontaneous Raman scattering effect and the optical time domain reflection principle, the invention skillfully merges the technologies of the distributed fiber Raman amplifier and the distributed fiber Raman photon temperature sensor and achieves the ultra-long-range distributed fiber Raman temperature sensor.

The invention discloses a chaotic laser related Brillouin optical time domain analyzer integrated with an optical fiber Raman amplifier. The analyzer is manufactured by using a chaotic laser related principle, an optical fiber stimulated Raman scattered light amplification effect, the strain of coherently amplified Brillouin scattered light, a temperature effect and an optical time domain reflection principle. Through related processing of back detection light and local reference light of a sensing optical fiber, the spatial resolution of a sensor system is improved; a continuously-running high-power optical fiber Raman laser is used as a pump light source of the Brillouin optical time domain analyzer to overcome the difficulty that the frequencies of a detection laser and a pump laser are required to be strictly locked by an optical fiber Brillouin optical time domain analyzer; and a broadband optical fiber Raman amplifier replaces a narrow-band optical fiber Brillouin amplifier, so the gain of back coherently amplified stimulated Brillouin scattered light is increased, the signal-to-noise ratio of the sensor system is improved, and correspondingly, the measuring length and the measuring accuracy of a sensor are improved.

The invention discloses a non-relay optical fiber transmission system and method. The non-relay optical fiber transmission system comprises the following components that are sequentially connected with one another by transmission optical fibers: an optical transmitter, an optical power amplifier, an optical pulse expander, an optical fiber, a high-power optical fiber amplifier, a chromatic dispersion compensation module, an optical pulse compressor, a remotely-pumped optical preamplifier, a distributive optical fiber Raman amplifier, an optical preamplifier, a nonlinear optical loop mirror and an optical receiver. The remotely-pumped optical preamplifier is connected with a remotely-pumped source; and the distributive optical fiber Raman amplifier mainly consists of a Raman pumping source, a wavelength division multiplexer and an optical signal transmission fiber arranged behind the remotely-pumped optical preamplifier. In the invention, a linear chirped fiber grating is used for carrying out time-domain broadening on picosecond optical pulse; the picosecond optical pulse is amplified by the high-power amplifier and is transmitted in the optical fiber; the reversely arranged linear chirped fiber grating is used for compressing the time-domain expanded pulse and recovering the time-domain expanded pulse as the picoscond pulse, thus obtaining time spread gain, thereby leading the transmission distance of the non-relay optical fiber transmission system to be extended.

The invention discloses an ultra-long range 100km decentralized optical fiber Rayleigh and Raman scattering sensor. The sensor comprises an optical fiber pulse laser, an integrated optical fiber wavelength division multiplexer, an optical fiber narrow band reflection filter, an optical fiber shunt, an optical fiber Raman sensor, a 100km sensing optical fiber, a photoelectric receiving module, a digital signal processor and an industrial personal computer. The sensor adopts a decentralized optical fiber Raman amplifier, which amplifies a backward Rayleigh scattering signal generated by detection laser in a sensing optical fiber and having strain information, amplifies a backward anti-Stokes scattering signal with temperature information, improves the signal to noise ratio of a sensor system, increases the measuring length of the sensor, improves the reliability and the space resolution of the sensor and can measure the deformation, the cracks and the temperature of a field while measuring the field temperature, and the deformation, the cracks and the temperature are not uncrossed. The sensor has the characteristics of low cost, long service life, simple structure, good signal to noise ratio and the like, and is applicable to petrochemical pipe monitoring, tunnel monitoring, large civil engineering monitoring and hazard forecast monitoring in a range of ultra-long range 100km.

Provided is a gain-clamped (GC) optical amplifier using a fiber Raman amplifier (FRA) having a Raman cavity. The FRA having a Raman cavity comprises a Raman fiber module (RFM) amplifying and outputting an input optical signal and a resonant cavity generating a Raman laser and a gain clamping laser (GC laser), wherein the resonant cavity is formed as a feedback loop between an input terminal and an output terminal of the RFM. Accordingly, a gain of an optical signal propagating along a core of RFM keeps a constant value regardless of input signal intensity by generating the GC laser for gain clamping between a wavelength band of the Raman laser and a gain band of input signals.

The invention relates to a single-frequency nanosecond pulse fiber raman amplifier. The amplifier is formed by orderly connecting a single-frequency nanosecond pulse laser seed source (1), an isolator (2), a laser delay device (3), a pumping laser (4), a signal/pumping laser beam combiner (5) and an energy transfer fiber (6) into a whole through a fusion splicer. According to the single-frequency nanosecond pulse fiber raman amplifier, nanosecond pulse laser is led as a seed source and a pumping source, so that limitation of stimulated Brillouin scattering (SBS) effect on output power is removed; and the single-frequency nanosecond pulse fiber raman amplifier has the advantages of narrow line width, narrow pulse width, high peak power, flexible gain wavelength, low amplified spontaneous radiation noise, simple structure, and the like, and has a great application prospect.

The invention relates to a multi-wavelength stable output method and its device of linear structure optical fiber laser based on the mixing gain of fiber Raman amplifiers and erbium-doped optical fiber amplifier. It includes optical fiber annular lens, optical coupler, fiber Raman amplifiers, erbium-doped optical fiber amplifier, and Sagnac ring filter. The Sagnac ring filter includes two polarisation controllers whose one end are respectively connected with synthetic end of the 3dB optical coupler. The invention combines the fiber Raman amplifiers and the erbium-doped optical fiber amplifier to restrain wavelength competition characteristic of the latter to realize optical fiber laser multi-wavelength stable output.

The invention discloses a fully-distributed optical fiber sensor in combination of an optical fiber Raman frequency shifter and a Raman amplifier. After shifting frequency for 13.2 THz by the optical fiber Raman frequency shifter, an optical fiber pulsing laser produces a broad spectrum Raman laser with a 1660nm wave band, wherein the broad spectrum Raman laser is served as the broad spectrum light source of the fully-distributed optical fiber sensor for performing the incidence of a sensing fiber; the deformation and the breaking of the optical fiber can be detected based on the reverse Rayleigh scattering strength ratio of the sensing fiber; the 1550nm wave band produced in the sensing fiber undergoes reverse anti-Stokes Raman scattering and is amplified by the optical fiber Raman amplifier; the temperature information at each section of the optical fiber can be obtained by deducting the influence produced by straining according to the strength ratio of the anti-Stokes Raman scattered light to the Rayleigh scattered light; the inspection on the training and the temperature is out of cross effect; the detection point on the sensing fiber can be located by using an optical time domain reflection technology. The fully-distributed optical fiber sensor is applied to the monitoring of petrochemical pipes, tunnels and large-scale civil engineering within ultra-long range of 100 kilometers, as well as disaster prediction monitoring.

The related loop fiber laser multiple wavelength output device based on mixed gain of Lamb amplifier and erbium-doped fiber amplifier comprises: an optical loop with second port connected with Sagnac loop filter included two polarization controllers whose another end connects with 3dB optical coupler port, an optical coupler, a fiber Lamb amplifier, and the erbium-doped fiber amplifier. This invention can output laser stably.

The present invention relates to a light amplifier capable of obtaining the gain and the noise characteristic required for a direct light amplification repeater in order to keep up with the trend toward higher transmission speeds. The light amplifier includes a Raman excitation section for backwardly Raman-exciting an input side optical fiber, a first discrete light amplifier capable of carrying out a discrete amplification of light from the input side optical fiber and Raman-amplified by exiting light from the Raman excitation section, a dispersion compensating fiber Raman amplifier capable of, while dispersion-compensating the light amplified by the first discrete light amplifier in a dispersion compensating fiber, Raman-amplifying the light propagating in the dispersion compensating fiber, and a second discrete light amplifier capable of carrying out a discrete amplification of the light from the dispersion compensating fiber Raman amplifier.

The invention provides a repeater-less optical fiber transmission system of a bypass forward Raman amplifier. After an optical single transmitted from an optical transmitter passes through an optical power amplifier and a first section of transmission optical fiber, a forward Raman amplifier enters into a signal light transmission optical fiber through the coupling of a first wave-division multiplexer so as to amplify the light signal; the light signal enters into a remote pump optical amplifier through a second section of transmission optical fiber so as to be amplified; a remote pump unit is connected with the remote pump optical amplifier to provide pumping light as a pumping source. And then, the light signal passes through the third section of transmission optical fiber, and a backward optical fiber Raman amplifier enters into the signal light transmission optical fiber through the coupling of the second wave-division multiplexer so as to amplify a weak light signal; and finally, the light signal enters into an optical receiver. A switch gain of the bypass third-order optical fiber Raman amplifier achieves 15-30dB, and a signal to noise ratio of the light signal transmitted by the optical fiber is improved, and then the transmission distance of the repeater-less light signal is prolonged.

The invention relates to a distributed fiber Raman amplifier. A light signal enters a transmission fiber through a fiber isolator, a tail end of the transmission fiber is connected with an input end of a wavelength division multiplexer, a pump signal input end of the wavelength division multiplexer is connected with a Raman pump laser device. Output of a signal public end of the wavelength division multiplexer is output of the distributed fiber Raman amplifier, and an amplified light signal is outputted. The transmission fiber of the distributed fiber Raman amplifier is inserted with one or two saturable absorbers for inhibiting Rayleigh noise. The absorber can be a semiconductor saturable absorber or a carbon nanotube saturable absorber. Length of the transmission fiber divided into two segments is about one half of a total length when one saturable absorber is inserted, length of the transmission fiber divided into three segments is about one third of the total length when two saturable absorbers are inserted. The distributed fiber Raman amplifier can further be a bidirectional pump distributed fiber Raman amplifier. The distributed fiber Raman amplifier effectively inhibits gain of the Rayleigh noise, realizes Raman amplification with high gain and low noise and improves an all-optical relay distance of fiber communication.

A semiconductor laser module including a semiconductor laser device having an integrated diffraction grating configured to output a multiple mode laser beam in the presence of a driving current, an optical fiber configured to guide the multiple mode laser beam to an output of the laser module, and an optical attenuation device configured to attenuate the multiple mode laser beam by an amount sufficient to provide a predetermined output power from the output of the laser module. The optical attenuation device may be an optical coupling lens offset from an optimum coupling position by an amount sufficient to provide the predetermined output power, or an optical attenuator interrupting the optical fiber and configured to attenuate the multiple mode laser beam by an amount sufficient to provide the predetermined output power. Also, a two fiber Raman amplifier having a super large area (SLA) fiber that provides amplification of the signal based primarily on the forward excitation light can also be used to suppress SBS.

This invention discloses a device for measuring fiber Raman gain system including a fiber laser, a pump-signal fiber WDM and a fiber spectrometer, among which, the input of the pump-signal fiber WDM is connected with the first fiber connector for connecting with a tested single mode fiber, the output of which is connected with the spectrometer via a second fiber connector and the pump end of which is connected with the fiber laser via the third fiber connector, which does not use a signal source but applies a fiber laser as the pump source to simplify the coupling mode and increase the efficiency.

The invention provides a gain spectrum regulation and control method and device for an optical fiber Raman amplifier, and the method comprises the steps: calculating an optimal estimation value of an optical fiber Raman amplifier gain spectrum in a current state through extended Kalman filtering, and calculating a first offset between the optimal estimation value and an ideal gain spectrum; and calculating a pumping wavelength offset and a pumping power offset according to the first offset and the first correlation matrix so as to determine the driving voltage adjustment amount of the flexible grid optical network; therefore, dynamic adjustment is realized, and the flatness of a gain spectrum of the optical fiber Raman amplifier can be greatly improved. Based on the perturbation theory, the relation between the pumping power adjustment amount and the gain spectrum variation of the optical fiber Raman amplifier under multiple pumping wavelength combinations is solved, a first correlation matrix is constructed, and efficient and rapid feedback adjustment can be achieved.

A pump source for a fiber Raman amplifier used in a WDM optical communication system is formed to generate an RF-modulated pump signal (as opposed to the prior art CW signals). The modulation frequency and index of the RF-modulated pump signal are controlled to impart a sufficient degree of“randomness” to the presence of the pump signal at each wavelength, thus minimizing cross talk between the signals and improving the transfer of power from the pump signal to the plurality of optical input signals.

The invention discloses a safety monitoring device of a distributed fiber Raman amplifier. The safety monitoring device comprises an intelligent control system which comprises an optical power splitter, two etalons, two optical detectors and a computing control module. An output end of the optical power splitter is connected with input ends of the two etalons; output ends of the two etalons are respectively connected with an input end of one optical detector; and output ends of the optical detectors are connected with the computing control module. The invention further discloses a safety monitoring method of the distributed fiber Raman amplifier. The safety monitoring device and method has the advantages of low cost, implementing easiness and convenience in popularization and commercialization; besides, with small environmental effect, the signal scanning is a dynamic process and the Raman amplifier is switched on and off dynamically, intelligently and quickly in real time; thus, personal safety and system security are protected and interference to systems from ineffective signals is avoided.

The invention discloses a distributed optical fiber sound wave and vibration fusion type sensing system, which comprises a laser, a 1*2 optical fiber coupler, an acousto-optic modulator, an erbium-doped fiber amplifier, a first fiber filter, a fiber circulator, a first optical switch, a fiber Raman amplifier, a second optical switch, a second fiber filter, a 3*3 fiber coupler, a first photoelectric detector, a second photoelectric detector, a third photoelectric detector, a data acquisition and processing unit, a computer and upper computer software. The system has the advantages that two sensing functions and modes of vibration and sound wave sensing are fused, different working requirements can be met, the defect that conventional distributed optical fiber sensing equipment only has single vibration or sound wave sensing is effectively overcome, the cost is saved, and the sensing system is an important technical improvement in the field of distributed optical fiber sensing; flexibleswitching can be performed according to different use requirements and scenes, the cost is saved, and the use is convenient; and a mode of switching between a vibration mode and a sound wave sensing mode by means of controlling an optical switch is provided, and the operation is flexible.

The invention discloses an equipment and method which is used to achieve automatic gain control of on line optical fiber Laman amplifier in optic transmission system, especially relates to an automatic gain control equipment and method in dense wavelength division multiplexing optic transmission system, when there are several pumping laser equipments at forward, backward or bidirection in optical fiber Laman amplifier. The invention monitors wavelength and power of optical fiber input end to calculate needed driving voltage and current of each pumping laser equipment of optical fiber Laman amplifier, and achieves to objective gain. Based on the signal changing of optical fiber input end, the system can control optical fiber Laman amplifier gain to hold the line or to achieve objective changing on line automatically. The invention gets the progress of simplifying control equipment, and achieves the effect of controlling gain of Laman amplifier on line automatically, saves equipment cost, and improves control precision and efficiency.

The invention discloses an optical fiber Raman amplifier, comprising: a section of single-mode optical fiber, the single-mode optical fiber includes at least one predetermined wavelength λ _P When excited by an optical signal, the fiber core generates stimulated emission of light by means of Raman scattering in a predetermined wavelength band, wherein the predetermined wavelength band includes at least one signal wavelength λ _s ; a first means for coupling an input optical signal to said single-mode fiber segment; a second means for coupling an optical excitation signal to said single-mode fiber segment; a high-pass with a cutoff frequency slightly lower than the frequency of the lowest frequency input signal optical filter, and the high-pass filter is arranged along the direction of the single-mode optical fiber section; wherein the second device for coupling the optical excitation signal includes a plurality of optical fiber sections, and is arranged between adjacent optical fiber sections A high pass filter, an excitation signal is provided as an input to a first fiber segment of the plurality of fiber segments, and an output of a last fiber segment of the plurality of fiber segments is coupled to the single mode fiber segment.