821 results about "Fiber ring" patented technology

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 fiber optic network transmits data between a hub node and a plurality of local nodes connected by at least one unidirectional fiber ring. Downstream data streams are carried on wavelength-division-multiplexed optical carriers from the hub node to the local nodes. An optical carrier corresponding to a specific wavelength carries downstream data streams to a specific local node. Downstream data streams are multiplexed onto an optical carrier via orthogonal frequency division multiplexing. A parallel signal detector in each local node detects all downstream optical carriers. A signal processing module demultiplexes the data stream from the optical carrier having the specific wavelength corresponding to the local node. An upstream data stream is multiplexed via orthogonal frequency division multiplexing onto an upstream optical carrier having the same specific wavelength and transmitted from the local node to the hub node. Upstream data awaiting transmission is allocated to specific subcarriers and time slots.

A ring laser includes a large-core rare-earth-doped fiber ring-connected with a free-space path having an electro-optic switch, output coupler, and intracavity band-pass filter to enforce lasing operation in narrow wavelength range. In some cavity-dumped modes, the laser is configured in a similar manner, except that an output coupler is omitted since the optical power is extracted from the laser cavity by the electro-optic switch itself. The same laser can be configured to operate in Q-switched and/or cavity-dumping modes as well as in hybrid modes (e.g., partial Q-switch, followed by cavity dumping, or even CW). In some embodiments, the laser can be used as, or inject laser light into, a regenerative solid-state amplifier, or a Raman laser, or can be also used to generate visible, ultra-violet, mid-infrared, and far-infrared (THz) radiation via nonlinear wavelength conversion processes. The various embodiments can use a power oscillator or seed-plus-amplifier MOPA configuration.

The invention enables protection of a ring frame transferred via an inter-ring bridge ring node when a fault occurs at the node in a multiring. Ring nodes form a ring protection domain to enable one ring node to be bypassed by using other ring nodes when a fault occurs at this ring node. The TTL value of ring frame to be transferred through the bypass is set to a value obtained by adding the number of hops h to the faulty ring node to a common initial value A in the same two-fiber ring to enable detection of a characteristic TTL value at a bypassing ring node. The bypass fur the ring frame is selected with reference to the characteristic TTL value at the bypassing ring node.

The invention relates to a measuring method of the quality of optical fiber ring, used in an optical fiber gyroscope, and a and measuring device thereof; the measuring method and the measuring device belong to the technological field of optical measurement and optical fiber sensing. The method includes the following steps: exerting radial and axial temperature excitation on the optical fiber ring (constant power heating, periodic power heating or non-periodic power heating); measuring the characteristics of the transient temperature of the optical fiber ring; acquiring the test signals of the characteristics of the transient temperature of the optical fiber ring; analyzing and processing the collected data according to the numerical value simulation result of three-dimensional mathematical model of the optical fiber ring; and acquiring the equivalent but asymmetric information of the quantized optical fiber ring which is wound in the radial and axial directions. The device comprises a measuring light source, an optical device which has three ports, a Y wave guide, an optical detector, a signal generator, an electric signal amplification circuit, a controllable heating device, a control circuit and a set of controlling and calculating software. The measuring method can accurately, conveniently and rapidly measure the quality of temperature symmetry of the optical fiber ring, but also can determine the dynamic characteristics of the optical fiber ring without installing the finished product of the optical fiber gyroscope. Thus the measuring method is conducive to the mass production and measurement of the optical fiber ring.

The invention discloses an all-fiber current sensor consists of a 3x3 polarization-maintaining fiber coupler. One embodiment of the invention, a straight-through type interferometric all-fiber current sensor, comprises a light source, a 3x3 polarization-maintaining fiber coupler, fiber polarizers, a 1/4 fiber wave sheet and a transduction fiber ring. The light source is connected with one end of the 3x3 polarization-maintaining fiber coupler; the two ports of the 3x3 polarization-maintaining fiber coupler are respectively connected with two fiber polarizers; and the other ends of the two fiber polarizers are respectively connected with the transduction fiber ring by the 1/4 fiber wave sheet; one port of the 3x3 polarization-maintaining fiber coupler is vacant; and the rest two ports of the 3x3 polarization-maintaining fiber coupler are respectively connected with a signal processor by two photoelectric detectors. In addition, another embodiment of the invention, a reflection type interferometric all-fiber current sensor, also uses the 3x3 polarization-maintaining fiber coupler. The all-fiber current sensor avoids phase differences made artificially and makes the current transduction system woke more stably.

This invention discloses one triangle wave phase modulation method and device of resonance chamber fiber top, wherein, the laser is connected to first couple device, first phase modulator, second couple device, third couple device, fourth couple device, second phase modulation device and first couple; the first phase modulation and first triangle wave signal generator are connected; the second phase modulation and second triangle signal generator are connected; the second couple device and first photoelectricity, first high speed digital signal processor and laser are connected; the fourth couple device is connected to fourth couple device, second photoelectricity detector, second high speed digital processor; the third couple device is connected to the fiber ring.

The invention provides a few-mode fiber mode coupling measurement device based on a two-photon lantern and a few-mode fiber circulator and belongs to the technical field of fiber characteristic measurement. The few-mode fiber mode coupling measurement device is composed of a light source, a photon lantern A, a few-mode fiber circulator, a measured fiber, a photon lantern B, a photoelectric detection module and a signal processing module. An optical pulse signal generated by the light source is subjected to spatial mode conversion through the photon lantern A to output a designated single stimulus mode, combined with the single-way transmission characteristics of the few-mode fiber circulator, the stimulus mode enters the measured fiber through the few-mode fiber circulator, a backward Rayleigh scattered light generated by coupling the stimulus mode in the measured fiber and the stimulus mode to the non-stimulus mode enters the photon lantern B through the few-mode fiber circulator for spatial model demultiplexing and being output from a corresponding mode port, and the output backward scattered light of each path is subjected to photoelectric detection and data processing, so that the measurement of the few-mode fiber mode coupling coefficient is achieved.

The invention discloses an online detection device and method for polarization axis alignment in the direct coupling process of a polarization-preserving fiber ring and a Y waveguide. The polarization axis online detection device comprises a polarization axis detection device and an image processing module. The polarization axis detection device comprises an illumination system, an imaging system and a CCD camera. The imaging system comprises a reflective optical element and an objective lens, and is used for imaging and magnifying the end face of the Y waveguide and the end face of a tail fiber assembly of the tail the polarization-preserving fiber ring. The method comprises the steps that (1) the Y waveguide and the tail ring assembly of the polarization-preserving fiber ring are mounted, and the end face of the Y waveguide and the end face of the tail ring assembly of the polarization-preserving fiber ring are adjusted to be in parallel; (2) the imaging system is adjusted to enable the CCD camera to obtain a clear image; (3) the image is collected to a memory, and the deviation angle of the polarization axis of the Y waveguide and the fiber polarization axis of the polarization-preserving ring is acquired and calculated. According to the online detection device and method, the relative position information of the polarization axes of the polarization-preserving ring and the Y waveguide in the direct coupling process can be acquired in real time, quantitative evaluation can be made for the final state of the alignment of the polarization axes, and a foundation is laid for further improving the axis alignment precision.

The invention is comprised of communication devices designed to provide an array of communication services from network systems to a residential or business consumer through broadband wireless communications. The invention provides a diverse mixture of communication services by utilizing a media access control (MAC) and asynchronous time division multiplexing technique. The invention uses a time slotted transmission scheme where data from communication services are multiplexed according to their delivery requirements which include bandwidth, delay and loss requirements. The invention primarily is comprised of a subscriber unit system and a base station system. The base station system is connected to network systems by a metropolitan fiber ring or terrestrial microwave system using SONET and/or ATM/optic protocols. A base station provides the communication service to the consumer by; 1) receiving a request for a communication service over a wireless transmission link; 2) in response to receiving the request, dynamically configuring a media access control layer in a wireless transmission link for the requested communication service; and 3) generating and transmitting an instruction to provide the requested communication service over the wireless transmission link using the dynamically configured media access control layer.

The invention relates to a fiber grating Fabry-Perot (F-P) cavity vibration sensor and a vibration measurement system thereof. The invention is technically characterized in that a fiber grating F-P cavity is stuck to the middle position of a cantilever beam; and one end of the cantilever beam is fixed on a support, and the other end thereof is connected with a mass block. The measurement system using the vibration sensor is characterized in that one side of the intensity-demodulation type fiber grating F-P cavity vibration sensor is extended into a fiber index-matching liquid, and the other side thereof is connected with the port of a terminal B of a fiber circulator via single-mode fiber; a terminal A of the fiber circulator is connected with a narrow-band light source; and a terminal C of the fiber circulator is connected with a photoelectric detector. By adopting the fiber grating F-P cavity, optical signals can resonate in the F-P cavity to form interference peaks, so that the accuracy of the detection can be greatly increased; meanwhile, by adopting the intensity-demodulation manner of narrow-band light source irradiation, the detection frequency of the vibration sensor can be increased from a few hertz to hundreds of hertz; and the invention can measure the frequency and amplitude of weak vibration signals at the same time, and improve the measurement accuracy.

A fiber optic ring interferometer, such as an interferometric fiber optic gyro (IFOG), with a sensing loop doubler. The IFOG device includes a light source, a circulator in optical communication with the light source and a photo diode, an integrated optical chip (IOC) capable of splitting light emitted from the circulator into two paths each of which is capable of being modulated, the IOC further being capable of combining light from each of the two paths when light travels in a direction towards the circulator, a fiber coil, and a polarization maintaining (PM) combiner/splitter disposed in between the IOC and the fiber coil. The PM combiner/splitter operates to send light through the fiber coil a first time in a first polarization state and to subsequently send the same light a second time through the fiber coil in a second orthogonal polarization state, whereby light travels twice the distance compared to a single loop IFOG device and, as such, effectively doubles the LD product.

An apparatus for detection and measurement of trace species in a gas or liquid sample. A ring down cell formed from a fiber optic ring is exposed to the sample gas or liquid. A coherent source emits radiation into the fiber optic ring, which in turn is received at an output thereof. The fiber optic ring has a portion thereof, between the input and output, exposed to the sample gas or sample liquid. A processor is coupled to the receiver and determines the level of trace species in the gas or liquid sample based on the rate of decay of the radiation within the fiber optic ring.

The invention discloses a distributed fiber disturbance sensor based on a Sagnac interferometer. A Sagnac interferometer is used for coupling an arm, synchronously a delayed fiber ring is added, namely a delayed fiber ring is superposed in a single Sagnac interferometer to form two Sagnac interferometers with different length; the time division multiplexing of the two Sagnac interferometers with different length is realized by the propagation of optical pulses in the interferometer; and the positions of disturbing points are calculated to realize the distributed sensing of the disturbance according to the amplitude of output signals of two Sagnac interferometers. The sensor has the advantages of low cost, simple structure and good stability.

The invention discloses a millimeter wave generating device based on an optic-fiber ring resonator and a method thereof. The optic-fiber ring resonator is formed by connecting a semiconductor optical amplifier, a 1*2 polarization maintaining coupler, a Mach-Zehnder intensity modulator, a three-port polarization maintaining circulator, a polarization maintaining fiber grating and a polarization maintaining optical delay line in sequence, the output of the optic-fiber ring resonator obtained through the other output end of the 1*2 polarization maintaining coupler is connected with a high-speed photoelectric detector through an optical comb filter with an adjustable wavelength, and when the Mach-Zehnder intensity modulator modulates a microwave source with the frequency being fm, and millimeter wave signals with the being 4fm are generated at the radio-frequency output end of the high-speed photoelectric detector through controlling the DC offset voltage of the Mach-Zehnder intensity modulator and the length of the fine-tuning polarization maintaining optical delay line. The invention has the advantages of high millimeter-wave efficiency, compact structure, stable operation, electromagnetic interference resistance and the like.

A novel fiber optic gyro interference light path based on photonic crystal fiber includes a photonic crystal fiber ring and a Y waveguide integrated optical device. The optical fiber ring adopts an refractive index guided photonic crystal fiber; for winding of the fiber ring, a mode of solidifying one layer after winding is employed; and the Y waveguide tail fiber employs the same type of fiber as the optical fiber ring. The design of photonic crystal fiber meets the requirements of birefringence of gyro and at the same time has the mode field as Y waveguide chip, and a shrinkage cavity method is used for further expansion of the field mode of the optical fiber, so as to reduce additional loss caused by optical fiber splicing. The designed interference optical path has the characteristics of good polarization stability, low magnetic field polarization sensitivity and radiation resistance; the fiber optic gyro using the interference light path has the characteristics of radiation resistance, good temperature stability and low magnetic field sensitivity, and is especially can be used as high precision fiber optic gyroscope for satellite and other space vehicles.