53 results about "Fiber ring laser" patented technology

A distributed fiber sensor based on spontaneous Brillouin scattering uses a single-frequency fiber laser as a source and a cw Brillouin fiber ring laser as an OLO to optically shift the frequency of the OLO to set the Brillouin / OLO beat frequency within the bandwidth of a conventional heterodyne receiver. The distributed fiber sensor is capable of real-time measurement of both temperature and strain.

A single-frequency Brillouin fiber ring laser with extremely narrow linewidth comprises a single-frequency narrow-linewidth rapid-tunable pump laser, a temperature-controlled acoustically-damped package for Brillouin fiber ring laser cavity, and an auto-tracking feedback electronic loop with novel configuration for active stabilization. The Pound-Drever-Hall frequency-locking technique is employed to keep pump laser frequency in resonance with one of the Brillouin fiber ring cavity modes. Instead of changing cavity length of Brillouin fiber ring laser, the pump laser frequency is rapidly tuned in the auto-tracking feedback electronic loop. This enables extremely narrow linewidth radiation emitted from a Brillouin fiber ring laser without stretching the fiber ring. Dual-wavelength actively stabilized Brillouin fiber ring laser may be generated from a single ring cavity by polarization-combining or wavelength-combining two pump laser beams and using two independent feedback loops to the two operation wavelengths.

A system and method for generating an optical laser pulse train of constant ultrashort pulse duration and low timing jitter in a fiber ring laser system (resonator) while keeping the laser resonator resilient to environmental conditions like temperature, humidity and pressure. The laser resonator may be actively mode-locked with a periodic electrically driven modulation at a specific frequency that corresponds to the inverse of the transit time inside the resonator. The optical pulse train quality may be monitored in real time, and the frequency of the modulation may be dynamically tuned in real time to compensate for resonator length changes due to changes in the environmental conditions.

A ring-laser system that includes a plurality of ring-laser gain elements and a spectral-beam-combining output stage configured to combine a plurality of beams coming from the gain elements into an output beam and that includes chromatic-dispersion compensation. In some embodiments, the output stage includes a plurality of highly reflective dielectric-coated focussing elements. In some embodiments, the output stage includes a plurality of high-efficiency dielectric-coated grating elements. In some embodiments, the output stage includes a mostly reflective but partially transmissive output mirror and a highly reflective beam-reversing mirror configured to reflect a majority of a backward-traveling signal beam such that it becomes forward traveling. In some embodiments, each gain element further includes a photonic-crystal-rod power amplifier. Some embodiments have an amplitude modulator configured to pulse the plurality of beams, and a timing controller configured to synchronize the pulses of the plurality of beams. Some embodiments further include a non-linear wavelength-conversion device.

An optically-pumped mode-locked fiber ring laser for optical clock recovery of multiple wavelength division multiplexed optical signals actively mode-locks a plurality of outputs of the laser as a plurality of recovered clocks for a plurality of the multiple wavelength division multiplexed optical signals. The laser cavity has a cavity length corresponding to an integer multiple of bit periods of at least one of the multiplexed optical signals for receiving a pre-amplified version of the plurality of wavelength division multiplexed optical signals to provide gain modulation through a phase-insensitive parametric amplification and recirculating a proportion of the output from the laser cavity back through the laser cavity for spatially mode-locking the output of the laser cavity as a recovered clock.

This invention discloses to a type of fiber gas lasers and fiber ring laser gyroscopes based on these fiber gas lasers. The fiber gas lasers comprise of excitation gases, optical resonator and excitation source, etc. The optical resonator is made by connecting two selected arms of a single mode fiber coupler to the two ends of hollow-core fiber to form a ring resonator. The hollow-core of the fiber is filled with excitation gases to act as gain medium. The fiber laser is simple to construct, lower cost, and has adjustable size and good amplification performance. The fiber ring laser gyroscopes based on this novel type of gas lasers can be applied on robotics, automobile navigation, etc.

An all-optical true random number generator with a Tbps code rate comprises an all-optical true random number entropy source and an all-optical quantizer, wherein the all-optical true random number entropy source adopts an rational harmonic mode-locked Er-doped fiber ring laser, actually a ring-shaped cavity formed by a lithium niobate electro-optic modulator, an optical band pass filter I, an erbium-doped fiber amplifier, an opto-isolator and an optical coupler which are connected through fiber; and the all-optical quantizer is a quantum dot quarter wave phase-shift distributed feedback type laser. The generator provided by the invention solves the problems that the code rate is too low and untunable in the prior art, has a Tbps-level code rate, is in direct compatible with an optical network, and meets the safety requirements of modern high-speed secure communication.

The invention relates to a tunable erbium-doped fiber ring laser which can output stable wavelength and power, which relates to an optical fiber communication technology. The tunable laser and an isolator of the invention are connected with the ring cavity through an input terminal of a first optical coupler, the 980nm pumping is optically coupled in the erbium-doped fiber gain medium by a WDM coupler; a second optical coupler is an output terminal; through controlling phase-shift phase of phase-shifted grating, filtering function can be realized; through regulating the wavelength of the injected laser of the tunable laser, injection locking can be realized and the laser can be stably outputted. The tunable single-longitudinal erbium-doped fiber ring laser of the invention has the advantages of low cost, simple device and easy operation; the tunable single-longitudinal mode output with output wavelength and wavelength of stable power can be finally obtained.

The present invention discloses a bidirectional transmission network apparatus based on a tunable rare-earth-doped fiber laser source. It is useful in wavelength-division-multiplexing access networks. The fiber ring laser not only generates downstream data traffic but also serves as the wavelength-selecting injection light source for the Fabry-Pérot lasers (or vertical cavity surface emitting lasers) located at the subscriber site. The fiber laser is constructed based on optical filtering, polarization control and noise suppression techniques.

The invention is a device and measuring method for using Brillouin optical fiber circle laser to measure linewidth of ultra-narrow laser, which relates to a measuring device and method for laser linewidth. The output of the laser source is connected to the input of the isolator, the output of the isolator is connected to the input of the fiber coupler, the output of the coupler is connected to the inlet of the fiber coupler, the output of the fiber coupler is connected to the input of the photoelectric diode, the output of the photoelectric diode is connected to the input of the frequency spectrum analyzer, the fiber circular cavity is formed by connection one end of the aperture circle made up of unimodular fiber and the port of the fiber coupler, another end of the aperture circle is connected to the port three of the coupler. The method is: the laser needed to be measured is sent into the fiber circle cavity, when the power of the laser needed to be measured reach the threshold of SBS, it generates a first order Stokes light in the coupler, when the power of the first order stokes light reach the SBS threshold, it generates the second order stokes light in the coupler, then the second order stokes light and the laser needed to be measured frequency are analyzed by the frequency spectrum analyzer, and the linewidth can be acquired.

A method and apparatus for producing single mode random fiber ring laser by inducing random distributed feedback in a short section of the fiber ring to thereby enable single mode lasing while reducing frequency jitter and relative intensity noise. The random distributed feedback maybe achieved through deep refractive index modulation at a series of randomly distributed laser-irradiated points inscribed along the length of the induced random distributed feedback fiber. The laser-processed random distributed feedback fiber maybe incorporated into the fiber ring in conjunction with a variable optical attenuator and band pass optical filter for enhancing the single mode operation.

A tunable single-frequency erbium-doped fiber ring laser stable in output wavelength and power comprises an erbium-doped fiber amplifier, wherein, a polarization controller is connected with the erbium-doped fiber amplifier; a 1x2 optical coupler is connected with the polarization controller through single mode fiber; a 2x2 optical coupler is connected with the 1x2 optical coupler through single mode fiber; the heads and the tails of the other two ends of the 2*2 optical coupler are connected through single mode fiber; the 1x2 optical coupler is connected with the 2x2 optical coupler through single mode fiber; a filter is connected with the 1x2 optical coupler through single mode fiber; the other end of the filter is connected with the erbium-doped fiber amplifier, forming a main ring cavity; an adjustable laser is connected with the optical coupler by using an optical isolator through single mode fiber, and the adjustable laser is used to stabilize the output wavelength and power of the laser.

A distributed Brillouin optical fiber sensing system based on coherent detection comprises a pump laser and couplers. Lasers emitted by the pump laser are divided into two routes of detecting light through the first coupler. The first route of detecting light enters a Brillouin optical fiber annular laser device of a lower arm light path, and output Brillouin lasers serve as local oscillation light. The second route of detecting light enters a distributed Brillouin optical fiber sensor of an upper arm light path, and obtained backward Brillouin signal light with temperature and strain information serves as scattered light. After frequency mixing is conducted on the Brillouin signal light and the Brillouin lasers through the second coupler, the Brillouin signal light and the Brillouin lasers are connected to a photo-electric detector to undergo photo-electric conversion. The distributed Brillouin optical fiber sensing system based on coherent detection has the advantages that high nonlinearity optical fibers are adopted in the Brillouin optical fiber annular laser device, the output Brillouin lasers are small in line width and stable in frequency, and sensing precision is increased; the distributed Brillouin optical fiber sensor can measure temperature and strain signals at the same time, and therefore high-frequency detection is converted to low-frequency detection, cost is greatly saved, and system complexity is lowered.

A laser device is composed of actively mode-locking ring optical fibre laser device and cavity length stabilized feedback loop. Said ring laser device is composed of dispersion compensating fibre (DCF), adjustable optical band-pass filter, polarizer, polarization holding fibre, M-Z model LiNbO3 electro-optical modulator, two optical couplers, optical isolator, optical fibre amplifier and electrically controlled optical delay line. It can increase the wavelength stability of laser device to + / - 0.01 nm.

A fiber ring laser is provided, which includes an optic amplifier, a first optical coupler (OCP), a second OCP, a first fiber ring, a second fiber ring, a first polarization controller (PC), and a second PC. The first fiber ring is coupled to the optic amplifier, the first and the second OCPs. The second fiber ring is coupled to the first and the second OCPs. The optic amplifier amplifies a first laser beam with a specified wavelength range. The first fiber ring receives the first laser beam. The first and the second fiber rings respectively provide a first and a second resonant cavities. The first and the second PCs respectively control polarization states of the first and second resonant cavities. The first laser beam resonates in the first and the second resonant cavities to generate a second laser beam with a first and a second wavelengths.

The invention relates to the technical field of ultrafast laser, in particular to a method for full optical control and precise synchronization of femtosecond, picosecond, nanosecond laser pulses with various wavelengths. The method adopts an injection-locked laser synchronization structure, uses the output light of a femtosecond pulse laser as control light, injects the output light into a fiber annular laser, utilizes the nonlinear effect of fiber to have crossed phase modulation or gain modulation control and realizes laser synchronization. The method has the advantages that the length of the fiber injected by femtosecond pulse can be arbitrarily set to realize long-distance laser pulse synchronization; according to elements doped to the gain fiber of the selected annular laser, the method can realize the synchronization of the laser pulse with various wavelengths; and through a translation platform for controlling the length of a cavity of the optical annular laser, the method can realize the output of mode-locked pulse with adjustable width from picosecond to nanosecond, keep synchronization between the output pulse and the injected femtosecond pulse, control a plurality of the fiber annular lasers and realize synchronization between a beam of femtosecond laser and a plurality of beams of laser with different wavelengths and pulse widths.

Unique gas cell constructions based on a hollow-core photonic crystal fiber are used, for example, inside a fiber ring laser cavity as an intracavity gas cell. In one embodiment, two simple terminal blocks are coupled to opposite ends of the hollow-core photonic crystal fiber. Each block features a main through-bore with an optical window at one end and an optical fiber chuck fitted at the other end, while a transverse bore intersects the main bore and features a gas fitting for connection to a gas source or vacuum pump. In another embodiment, the hollow-core photonic crystal fiber is contained within an enclosure whose exterior walls are fitted with optical windows and gas ports. Inside the enclosure, fiber clamps supports the ends of the hollow-core photonic crystal fiber at positions adjacent to an in alignment with the optical windows.

The invention relates to an optical gyroscope, in particular to a fiber laser gyroscope. It consists of an ultra-narrow linewidth fiber mode-locked laser, a wavelength division multiplexer, a fiber Sagnac loop, a circulator, a polarizer and a detector, and a difference frequency signal processing circuit. It is characterized in that it uses a semiconductor pump with a pigtail Active fiber ring laser with Sagnac effect composed of laser, isolator, wavelength division multiplexer and gain fiber; two sets of fiber coupler, circulator, ultra-narrow linewidth photon injection fiber mode-locking device, polarizer and detector The mode selection filter output system composed of the device forms the optical path scheme of the fiber laser gyroscope. The photon injection fiber mode-locking technology introduced in the present invention can make the gyroscope work stably in the ultra-narrow linewidth single longitudinal mode laser state, thereby obtaining the high-resolution detection result of the angular rate; The difference can automatically eliminate the zone-locking effect of the laser gyro. As a high-precision gyroscope, the invention can be applied to inertial measurement units of aviation, spaceflight, navigation and land weapons.

The invention provides a bending sensing measuring system based on a fiber ring laser. The system is characterized in that a fine core fiber is welded into a resonant cavity of a fiber ring laser, wherein the fiber ring laser comprises a pumping laser, a wavelength division multiplexer, a erbium-doped fiber, an photocoupler, an 1*2 fiber coupler and a polarization controller; the fine core fiber is used for bending sensing and can be also sued as an optical filter; when in application, the fine core fiber is attached on the surface of an object to be measured; the output laser central wavelength of the fiber ring laser is measured through the fiber spectrograph, and then the bending degree of the object to be measured can be measured. According to the system, the mode selecting characteristics of the laser resonant cavity is utilized; the system has the characteristics of being high in detection signal, high in signal-to-noise ratio, narrow ling width, high in sensitivity, and free of temperature sensitivity, and can be applied to various actual engineering.

The invention discloses a system and method for simultaneously measuring the lengths of two optical fibers. The system comprises an optical fiber ring laser, a second standard single-mode optical fiber to be tested, a reflector or a coupler, a photoelectric detector and a data collecting and processing system, wherein the optical fiber ring laser is formed by sequentially connecting a semiconductor optical amplifier or an erbium-doped optical fiber optical amplifier, a polarization controller, an output coupler and a first standard single-mode optical fiber to be tested through an optical fiber patch cord. One end of the second optical fiber to be tested is connected with the output coupler, and the other end of the second optical fiber to be tested is connected with the reflector; or the two ends of the second optical fiber to be tested are connected with two ports in one side of the 50 / 50 coupler, and the optical fiber ring laser is connected in two ports in the other side of the coupler. Optical signals output by the output coupler are converted into electric signals through the photoelectric detector, and the electric signals enter the data collecting and processing system. The time interval of two stages of adjacent correlation peaks or the frequency interval of two stages of adjacent harmonic peaks are obtained by calculating the autocorrelation function of chaos waveform data output by the system or through the Fourier transform, and therefore the length of the first optical fiber to be tested and the length of the second optical fiber to be tested are obtained through conversion.

A wavelength-tunable directly modulated fiber ring laser is provided. Generally speaking, the wavelength-tunable directly modulated fiber ring laser employs an RSOA (reflective semiconductor optical amplifier) and an OTF (optical tunable filter) to construct a novel ring resonant cavity. Additionally, a signal generator can be further employed to transmit modulated signals to the RSOA, whereby generating light wave with the modulated signals, so as to provide tunable wave-length and direct modulation at the same time.

There is provided a millimeter wave band frequency optical oscillator predicted to be used as a millimeter wave oscillating frequency signal source in a base station of a millimeter wave wireless transmission system. The optical oscillator has a double resonator structure in which a pair of wavelength tunable fiber grating mirrors are inserted into a unilateral fiber-ring laser resonator in order to internally and additionally form a linear laser resonator. The double resonator structure composed of the two stable laser resonators can oscillate laser of two modes. Due to a beat phenomenon occurring between the two modes, received laser is modulated to an ultra-speed frequency of 60 GHz or greater. A variation in the gain within a resonator is induced by a polarization controller using the dependency of laser modes upon polarization. A modulation frequency is consecutively changed from 60 GHz to 80 GHz by controlling the wavelength of light reflected by the fiber grating mirrors.

An optically-pumped mode-locked fiber ring laser for optical clock recovery of multiple wavelength division multiplexed optical signals actively mode-locks a plurality of outputs of the laser as a plurality of recovered clocks for a plurality of the multiple wavelength division multiplexed optical signals. The laser cavity has a cavity length corresponding to an integer multiple of bit periods of at least one of the multiplexed optical signals for receiving a pre-amplified version of the plurality of wavelength division multiplexed optical signals to provide gain modulation through a phase-insensitive parametric amplification and recirculating a proportion of the output from the laser cavity back through the laser cavity for spatially mode-locking the output of the laser cavity as a recovered clock whereby the recovered optical clock each having a periodic train of optical pulses with a repetition rate corresponding to the clock rate of the corresponding multiplexed optical signal is generated by mode-locking of the optically-pumped laser produced by a spatial modulation of the phase-insensitive parametric gain produced by the pulsed nature of the wavelength division multiplexed optical signals. A nonlinear gain medium disposed in the cavity has a sufficiently large dispersion at all of the wavelengths corresponding to the multiple wavelength multiplexed optical signals for minimizing four-wave mixing crosstalk among the multiple wavelength multiplexed optical signals, among the recovered clocks, and between the plurality of multiple wavelength multiplexed optical signals and the recovered clocks. The gain medium is pumped by the plurality of pre-amplified multiplexed optical signals to provide efficient gain modulation through the phase-insensitive parametric amplification at a plurality of narrow wavelength bands, each of the plurality of narrow wavelength bands immediately adjacent to a wavelength of a corresponding optical signal and each of the plurality of narrow wavelength bands including a corresponding recovered optical clock wavelength, and each of the corresponding optical signals copropagating in the laser cavity through the nonlinear gain medium with the recovered optical clocks. A parametric optical amplifier or a Raman amplifier having an inhomogenously broadened gain amplifies the plurality of recovered clocks for compensating a portion of the cavity loss at all wavelengths of the plurality of recovered clocks. A wavelength selector passes the light at the plurality of wavelengths of the recovered clocks for recirculation in the laser cavity and preventing the light from the multiple wavelength division multiplexed optical signals and a plurality of idler waves generated by four wave mixing between the multiple wavelength division multiplexed optical signals and recovered optical clocks from recirculating in the laser cavity.

In order to provide an optical sampling waveform measuring apparatus which can measure an ultra-high speed optical signal accurately by using a stable, narrow pulse, and a low timing jitter sampling optical pulse, an optical sampling waveform measuring apparatus is provided with a passive mode-locked fiber ring laser for generating a sampling optical pulse and a cavity length varying device which adjusts the cavity length in a passive mode-locked fiber ring laser.

The invention relates to a five-core fiber grating probe micro-scale measurement device and method based on an optical fiber ring-shaped laser and belongs to the technical field of manufacturing and measurement of precision instruments. The device comprises a pumping source, a wavelength division multiplexer, an Erbium-doped fiber, a saturable absorber, a multiway optical switch, an external reference grating, a five-core fiber grating probe, a computer and an optical spectrum analyzer; the pumping source is connected with a ring-shaped cavity formed by the Erbium-doped fiber, a circulator, a coupler and an isolator B through the wavelength division multiplexer; the coupler is connected with the optical spectrum analyzer and the computer by an isolator A to form an access. According to the method, the computer controls the multiway optical switch to switch optical paths, the optical spectrum analyzer is used for respectively measuring a wavelength of laser output by the optical fiber ring-shaped laser when the five-core fiber grating probe and the external reference grating are used as laser wavelength selection devices, and three-dimensional micro-scale measurement without temperature coupling is realized by utilizing a differential data processing algorithm. The five-core fiber grating probe micro-scale measurement device based on the optical fiber ring-shaped laser has the characteristics of integration of sensing and energy supply, compact system and high sensitivity.

A double-fiber grating probe microscale measurement device and method based on an optical fiber ring laser device belongs to the technical field of precise instrument manufacture and measurement. The device comprises a pump source, a wavelength division multiplexer, an Er-doped optical fiber, a saturable absorber, a multiway optical switch, an external reference grating, a double-fiber grating probe, a computer and a spectrum analyzer. Through the wavelength division multiplexer, the pump source is connected with a ring cavity composed of the Er-doped optical fiber, a circulator, the saturable absorber, a coupler and an isolator B; the coupler is connected in circuit with the spectrum analyzer and the computer through an isolator A. The method comprises controlling the multiway optical switch through the computer to switch light paths; measuring the laser wavelength output by the optical fiber ring laser device through the spectrum analyzer when the double-fiber grating probe and the external reference grating serve as a laser wavelength selector respectively; through a differential data processing algorithm, achieving non-temperature-coupled two-dimensional microscale measurement. The double-fiber grating probe microscale measurement device and method based on the optical fiber ring laser device has the advantages of integrating sensing and energy supply into a whole and being compact in system and high in sensitivity.

A wavelength-tunable directly modulated fiber ring laser is provided. Generally speaking, the wavelength-tunable directly modulated fiber ring laser employs an RSOA (reflective semiconductor optical amplifier) and an OTF (optical tunable filter) to construct a novel ring resonant cavity. Additionally, a signal generator can be further employed to transmit modulated signals to the RSOA, whereby generating light wave with the modulated signals, so as to provide tunable wave-length and direct modulation at the same time.