224 results about "Nonlinear optical fiber" patented technology

An apparatus generates femtosecond pulses from laser amplifiers by nonlinear frequency conversion. The implementation of nonlinear frequency-conversion allows the design of highly nonlinear amplifiers at a signal wavelength (SW), while still preserving a high-quality pulse at an approximately frequency-doubled wavelength (FDW). Nonlinear frequency-conversion also allows for limited wavelength tuning of the FDW. As an example, the output from a nonlinear fiber amplifier is frequency-converted. By controlling the polarization state in the nonlinear fiber amplifier and by operating in the soliton-supporting dispersion regime of the host glass, an efficient nonlinear pulse compression for the SW is obtained. The generated pulse width is optimized by utilizing soliton compression in the presence of the Raman-self-frequency shift in the nonlinear fiber amplifier at the SW. High-power pulses are obtained by employing fiber amplifiers with large core-diameters. The efficiency of the nonlinear fiber amplifier is optimized by using a double clad fiber (i.e., a fiber with a double-step refractive index profile) and by pumping light directly into the inner core of this fiber. Periodically poled LiNbO3 (PPLN) is used for efficient conversion of the SW to a FDW. The quality of the pulses at the FDW can further be improved by nonlinear frequency conversion of the compressed and Raman-shifted signal pulses at the SW. The use of Raman-shifting further increases the tuning range at the FDW. For applications in confocal microscopy, a special linear fiber amplifier is used.

The polarization direction of an optical signal is changed by a polarization controller so as to be orthogonal to a main axis of a polarizer. A control pulse generator generates control pulses from control beam with a wavelength which is different from the wavelength of the optical signal. The optical signal and the control pulse are input to a nonlinear optical fiber. In the nonlinear optical fiber, the optical signal, during a time period in which the optical signal and the control pulse coincide, is amplified with optical parametric amplification around a polarization direction of the control pulse. The optical signal, during the time period in which the optical signal and the control pulse coincide, passes through the polarizer.

The polarization direction of a signal is rotated by a polarization controller so as to be orthogonal to the main axis of a polarizer. A control pulse generator generates control pulses from control source with a wavelength which is different from the wavelength of the signal. The signal and the control pulse are input to a nonlinear optical fiber. In the nonlinear optical fiber, the signal, during the time period in which the signal and the control pulse coincide, has its polarization direction rotated by cross phase modulation, and is amplified by optical parametric amplification. The signal, during the time period in which the signal and the control pulse coincide, passes through the polarizer.

Enhancement of the supercontinuum generation performance of a highly-nonlinear optical fiber (HNLF) is accomplished by performing at least one post-processing treatment on the HNLF. Particularly, UV exposure of the HNLF will modify its dispersion and effective area characteristics so as to increase its supercontinuum bandwidth, without resorting to techniques such as tapering or introducing unwanted reflections into the HNLF. The UV exposure can be uniform, slowly varying or aperiodic along the length of the HNLF, where the radiation will modify the nonlinear properties of the HNLF. Various other methods of altering these properties may be used. The output from the HNLF can be monitored and used to control the post-processing operation in order to achieve a set of desired features in the enhanced supercontinuum spectrum.

A method of and device for generating an amplified optical signal directly in an optical fiber by way of phase-sensitive amplification based on one or more four-wave mixing (FWM) processes. In one embodiment, an input signal and two pump waves are applied to a highly nonlinear fiber (HNLF). The input signal is amplified in the HNLF due to energy transfer from the pump waves to the input signal via a degenerate phase-conjugation (PC) process. In another embodiment, an input signal and first and second pump waves are applied to a first HNLF to generate, via a Bragg scattering (BS) process, an idler signal corresponding to the input signal. The second pump wave is then filtered out and the first pump wave, a third pump wave, and the input and idler signals are applied to a second HNLF, where they interact via a non-degenerate PC process to produce an amplified output signal.

An optical waveguide fiber having a high threshold for stimulated Brillouin scattering is disclosed which is suitable as a nonlinear fiber. The optical fiber has a core with one or more core segments. The optical effective area at a wavelength of 1550 nm is less that 30 μm2.

The invention is directed to a method and an optical arrangement for the generation of a broadband spectrum in which wavelength regions are selected in an application-oriented manner already during spectrum generation in order to provide increased laser power. A passively mode-coupled solid-state laser provides picosecond laser pulses with an infrared output wavelength which is transformed to a secondary wavelength in the visible spectral range by nonlinear optical processes. The picosecond laser pulses are coupled into a nonlinear optical fiber which is optically adapted to the secondary wavelength with respect to dispersion and nonlinear characteristics, so that a radiation output interval comprising a visible wavelength region is selectively generated. The broadband spectrum has high brilliance and can be used, for example, in spectroscopy, microscopy, cytometry or for array readers.

Enhancement of the supercontinuum generation performance of a highly-nonlinear optical fiber (HNLF) is accomplished by incorporating at least one Bragg grating structure in the HNLF. The Bragg grating results in reflecting a core-guided signal into signal which also remains core-guided. The supercontinuum radiation generated by such an arrangement will exhibit a substantial peak in its energy at the grating resonance of the Bragg grating and a region of increased radiation in a narrow wavelength band on the long wavelength side of the peak. A number of such Bragg gratings may be formed so as to “tailor” the enhancements provided in the supercontinuum radiation. Various, well-known Bragg grating modifications (tuning, chirped, blazed, etc.) may also be used in the inventive structure to enhance the generated supercontinuum.

Apparatus and method for producing quantum entangled signal and idler photon pairs is provided. The apparatus makes use of a nonlinear optical fiber to generate the entangled photons. The use of an external broad band light source for alignment of any downstream measurement apparatuses is disclosed. One or more polarized output signals can be generated at both the signal and idler wavelengths using the alignment source, allowing the downstream measurement apparatuses to be aligned using classical light. Multiple signal and idler wavelengths can be generated and aligned using such a system.

A highly nonlinear optical fiber includes a core, a cladding surrounding the core, and a coating covering the cladding. A bending loss at a wavelength of 1550 nanometers with a bending diameter of 20 millimeters is equal to or less than 0.01 dB / m. A nonlinear coefficient at the wavelength of 1550 nanometers is equal to or more than 10 W−1km−1. A cut-off wavelength is equal to or less than 1530 nanometers. A zero dispersion wavelength is in a range between 1400 nanometers and 1650 nanometers. A diameter of the coating is 125 micrometers with a tolerance of ±5 percent.

An arrangement for generating beat notes with a relatively high signal-to-noise ratio (SNR) utilizes a pulsed laser source coupled into a section of post-processed highly-nonlinear optical fiber (HNLF) to generate a frequency comb having one or more regions of enhanced spectral power. A second laser signal source is overlapped with the frequency comb to form one or more “beat notes” at difference frequencies(y) between the second source and the continuum comb. By virtue of the post-processing, areas of spectral enhancement are formed along the comb, and are positioned to interact with the second laser signal to generate optical beat notes. The second laser signal may be from an external source (forming beat notes from a signal “outside” of the comb), or may be a frequency-multiplied version of the generated supercontinuum (forming beat notes from a signal “within” the comb).

The invention relates to a femtosecond laser carrier envelope offset frequency lock system based on a heterodyne interferometric method. The system is characterized by comprising a femtosecond laser light source system, an acousto-optic modulator, a controllable optical path retardation device, a light splitting prism, a first photoelectric detector, a phase lock amplifier, a phase difference voltage conversion device and a PID controller. Heterodyne interferometry can be conducted on first-level phase-shift diffraction light modulated by the acousto-optic modulator and zero-level diffraction light which is not modulated, and after mixing of interference signals with different wavelengths, direct-current level lock pulse envelope alignment is achieved; optical frequency comb envelope offset frequency is locked by means of interference signal phase, the linear process does not exist, high non-linear optical fibers, frequency doubling crystals and the like are not needed, and the system is simple in structure and low in requirement for laser energy.

The invention discloses a millimeter wave signal photonics generating method based on a highly non-linear optical stimulated Brillouin scattering effect and a millimeter wave signal photonics generating device, and belongs to the technical field of microwave photonics. The device consists of a tunable laser, a first coupler, two parallel Mach - Zehnder modulator, a first DC power supply, the second DC power supply, the third DC power supply, isolators, second coupler, a first photo detector, spectrum analyzers, high nonlinear optical circulator, a second photo detector, microwave amplifiers, intensity modulator, a fourth DC power supply and a microwave signal source. The millimeter wave signal generating device according to the selected output frequency is highly nonlinear optical fiber different in 54GHz to 66GHz. Since the stimulated Brillouin frequency shift value and the wavelength of the pump light of relevant, also can adjust the wavelength tunable laser, millimeter wave signal generator output frequency of the device is adjustable within a certain range.

The invention relates to SI (Spectrum Inversion)-based nonlinear fiber damage compensation method and device in an O-OFDM (Optical-Orthogonal Frequency Division Multiplexing) system, belonging to the field of optical communication and applied to the O-OFDM system for nonlinear fiber damage compensation. The whole compensation module is arranged in front of a receiver of the O-OFDM system and comprises an SI unit and an HNLF (Highly Non-Linear Fiber) which has a certain length and is arranged behind the SI unit, wherein SI is realized by an SOA (Semiconductor Optical Amplifier) based on FWM (Four Wave Mixing) effect.

The invention discloses an optically controlled optical PAM signal regeneration device comprising a power adapting unit, an optical clock control unit and a PAM reshaping unit, wherein the PAM reshaping unit is the core of a regenerator and is composed of a Mach-Zehnder interferometer MZI and a highly nonlinear fiber ring NOLM, for a to-be-regenerated degraded optical PAM signal, the level matching between the input degraded optical PAM signal and the PAM reshaping unit is accomplished by the power adapting unit, the optical clock signal power and the delay output by the optical clock control unit and a phase shifter in the MZI structure are adjusted, so that the PAM reshaping unit works normally, the loss coefficient, the optical fiber length, the nonlinear coefficient and other parameters of a highly nonlinear optical fiber in the NOLM structure, and the coupling coefficients of front and back couplers in the MZI structure are changed to design PAM reshaping units with different level numbers, and then the regeneration of the degraded optical PAM signal is accomplished. Therefore, the optically controlled optical PAM signal regeneration device disclosed by the invention can execute a reshaping and a re-timing function and has the advantages of flexible design of regeneration level numbers.

The present invention belongs to the field of optical fiber laser technology, and features that the full optical fiber multi-wavelength Raman laser with flat broadband envelope consists of high nonlinearity Raman gain fiber, two wideband WDM couplers connected on two sides of the Raman gain fiber separately, zero-dispersion high nonlinearity fiber, comb filter, wideband fiber loop reflectors on two ends and fibers to constitute laser transmission channel. The full optical fiber multi-wavelength Raman laser may have increased optical coupler and wideband fiber coupler to constitute single-way circulating fiber ring cavity. Compared with conventional optical fiber multi-wavelength Raman laser, the present invention has the advantages of utilizing pump source with small wavelength number in obtaining flat broadband envelope and flexible waveband design of the output laser spectrum.

The invention relates to a fiber optical parametric oscillator for achieving Fourier domain mode-locked laser output. Seed light output by two semiconductor lasers is modulated by phase and amplified by a high power optical amplifier to serve as pump light, the pump light is output from the pump output end of a wavelength division multiplexer and enters high nonlinear fiber through a polarization controller, and a part of the pump light is transferred into signal light in the high nonlinear fiber due to fiber nonlinear effect. After the signal light passes through a second optical isolator, dispersion-shifted fiber and a tunable filter, most energy is fed back to the high nonlinear fiber from a high power shunt ratio output end of an optical coupler with 9:1 power shunt ratio through the wavelength division multiplexer so as to form resonance laser output. When modulation frequency of the tunable filter is equal to fundamental frequency of a laser resonant cavity, the Fourier domain mode-locked laser output can be obtained. The fiber optical parametric oscillator achieves the Fourier domain mode-locked laser output, has significant application value in the fields of optical tomography, fiber bragg grating sensing and the like, and has the advantages of being high in wavelength scanning frequency, flexible in laser output spectrum tuning range control and the like.

The invention discloses a multi-frequency microwave signal photon instantaneous frequency measuring device with a super-wide frequency range, and belongs to the technical field of microwave photonics. The multi-frequency microwave signal photon instantaneous frequency measuring device with the super-wide frequency range comprises a laser, a coupler, a phase modulator, a polarization controller, a highly nonlinear optical fiber, a circulator, a first double-parallel MZ modulator, a second double-parallel MZ modulator, an intensity modulator, a microwave coupler, a photoelectric detector and a network analysis instrument. First-order upper side band signals output by the phase modulator are strengthened or weakened through the stimulated Brillouin scattering effect of the highly nonlinear optical fiber, the intensity balance of the first-order upper side band and the first-order lower side band of the output signals of the phase modulator is broken, and therefore instantaneous frequency measurement of multi-frequency microwave signals to be measured is achieved.

The invention relates to a multifunctional optical signal processing system. In the system, continuous detection light and signal light are combined through a first coupler and injected into a high nonlinear optical fiber; idle light generated in the high nonlinear optical fiber due to a fourwave mixing effect is divided into two paths through an optical filter and an optical coupler and are output, wherein one output path is connected to an optical power meter, the optical power output performs feedback control on a tunable dispersion compensator so as to realize dynamic dispersion compensation, while the other output path is used as a system output signal to generate an optical signal with high extinction ratio and no dispersion; and the wavelength of the output optical signal is changed by regulating the wavelength of the detection light, so that tunable wavelength conversion is realized. The multifunctional optical signal processing system can realize HNLF (High Nonlinear Fiber), dispersion detection, extinction ratio enhancement and wavelength conversion, has the advantages of multifunction integration, high response speed, high sensitivity of dispersion detection, wide working wave band and transparency to signal speed and modulation format and can be applied to an optical transmission system with channel rate of over 40Gb / s.

The invention discloses a safety monitoring system of a long-distance pipeline, comprising a transmitted and received light signal processing module 1, a light delay component 2, a single-line optical fiber 3 and a nonlinear optical environment 4 with a probing blind area, which are all formed into a variant-type optical fiber Sagnac interferometer. A polarization control element is used for ensuring the maximum interference intensity, and at least three wavelengths and three coherent light pulse signals are used for independently obtaining data to inhibit noise produced by the light source fluctuation and the polarization state change. The preservation time of A / D sampling is greater than the value of a pulse width, and the A / D sampling frequency is greater than the light source repetition frequency. A probe completely transforms each returned coherent light pulse so that an electric signal is undistorted. A single detection system has no relay to detect the distance of over 100 km.

The invention discloses a microwave photon up-conversion device and method based on a photoelectric oscillator and belongs to the technical field of microwave photonics. The device is composed of a laser source, a first coupler, a first circulator, a first high nonlinearity dispersion displacement optical fiber, an erbium-doped optical fiber amplifier, a first photoelectric detector, a second coupler, a first Mach-Zehnder modulator, a first microwave signal source, a first direct current voltage-stabilized power supply, an optical filter, a second Mach-Zehnder modulator, a second direct current voltage-stabilized power supply, a second circular, a second high nonlinearity dispersion displacement optical fiber, a second photoelectric detector, a microwave amplifier, a double-parallel Mach-Zehnder modulator, a third direct current voltage-stabilized power supply, a fourth direct current voltage-stabilized power supply, a fifth direct current voltage-stabilized power supply, an optical isolator and a spectrum analyzer. A Brillouin frequency shift value f of the high nonlinearity optical fiber is 9.2GHz, and a signal with frequency of f<m> can be up converted to f<m>+18.4GHz, so alow quality and low frequency intermediate signal is converted into a high quality and high frequency signal.

A method of fabricating an optical fiber preform using a modified chemical vapor deposition method and a nonlinear optical fiber fabricated using the method. The method comprises the steps of: forming a cladding layer and a core layer in a quartz glass tube; partially sintering the core layer; partially shrinking both ends of the quartz glass tube, in which the cladding layer and the core layer partially sintered are formed; and doping a sintered portion of the core layer with an impurity component, so that the optical fiber preform fabricated has a predetermined function. The nonlinear optical fiber being fabricated by a process comprising the steps of: forming the cladding layer and the core layer in a quartz glass tube; partially sintering the core layer; partially collapsing both ends of the quartz glass tube; and doping a sintered portion of the core layer with a predetermined impurity component.

The present invention relates to a figure-8 optical fiber pulse laser using a dispersion imbalanced nonlinear optical loop mirror (DI-NOLM). The conventional figure-8 optical fiber pulse laser uses a nonlinear optical fiber mirror having an EDF as a gain material. The conventional laser has an advantage for the simple structure, and it can be easily constructed. However, it can not produce the stable optical pulse trains. The figure-8 optical fiber pulse laser according to the present invention produces stable femto-second optical pulses using DI-NOLM. The optical amplifier is not included in DI-NOLM, instead, it is located at the unidirectional linear loop part. And the noise due to the bidirectional gain difference of the optical amplifier is reduced. Two optical fibers of different dispersion values are used at DI-NOLM. Therefore, the present invention provides a figure-8 optical fiber pulse laser using DI-NOLM improving the switching characteristic. Especially, the stable femto-second laser according to the present invention is applicable for the many applications such as high-speed reaction measurements, laser treatments, and medical lasers.

The present invention discloses a method for generating multiple and high frequency microwave signal source and a device thereof. The optical wave generated by laser is divided into two paths by the first optical amplifier through a first coupler / beam splitter. One path of optical wave emits into a Brillouin frequency shift module as a pump light for generating Stokes light with frequency shift. The other path of optical wave passes through an intensity modulator, a second optical amplifier and a high non-linear optical optical fiber. After the two paths of light are accessed into a second coupler / beam splitter, optical beat is generated on a photoelectric detector. The multiple and high frequency microwave signal is generated. The adoption of total optical plan can overcome the limit of electrionic bottleneck and is easy for realizing the generation of high frequency microwave signal. The multiple and high frequency microwave can be conveniently realized through stimulated Brillouin scattering in the optical fiber, the strength modulation of optical carrier and the equalization and stabilization effects of four-wave mixing of optical fiber, wherein the central frequency is determined by Brillouin frequency shift amount. The frequency interval can be freely adjusted through driving the microwave frequency. The requirement of applications of multiplexing wireless communication by subcarrier, etc. is satisfied.

The invention discloses a phase modulation signal full-optical wavelength conversion device. The phase modulation signal full-optical wavelength conversion device comprises a tunable dispersion compensator, an erbium-doped optical fiber amplifier, a variable optical attenuator, a tunable laser, a polarization controller, an optical beam splitter, a first optical coupler, a high-nonlinearity optical fiber, an optical filter and a signal demodulating and monitoring device. An output port of the tunable laser with the narrow linewidth is connected with an input port of the polarization controller. An output port of the polarization controller is connected with an optical integration port of the optical beam splitter. One optical splitting port of the optical beam splitter and an output port of the variable optical attenuator are connected with two optical splitting ports of the first optical coupler respectively. The first optical coupler, the high-nonlinearity optical fiber and the optical filter are sequentially connected. An output port of the optical filter and the other optical splitting port of the optical beam splitter are connected with a signal input port of the signal demodulating and monitoring device and a local oscillator input port of the signal demodulating and monitoring device respectively. Through the utilization of the phase modulation signal full-optical wavelength conversion device, harmonic suppression can be achieved, and signal quality is improved.

A high confinement nonlinear optical fiber is provided along with methods of parametric amplification for use thereof. The nonlinear optical fiber may include a plurality of concentric layers which are configured to provide different guiding regimes to low-frequency and high-frequency components through transverse geometry and refractive index profiling, thus reducing waveguide dispersion. The resulting optical fiber provides a parametric device with phase-matching in any spectral region of interest, such that a fiber optic parametric amplifier (FOPA) implementing the optical fiber can amplify in any spectral window of interest. A narrow-band FOPA configured to minimize phase mismatching is also provided for use with the optical fiber, and may be implemented as a light source or a monochromator.

The invention discloses an up-conversion device capable of achieving full-gloss microwave based on cross polarization modulation. The up-conversion device comprises a narrow line width laser, a first polarization modulator, a microwave signal source, a first polarization controller, a first optical filter, a circulator, a polarization beam splitter, a third polarization controller, a fourth polarization controller, an optical coupler, a high nonlinear optical fiber, a tunable laser, a waveform generator, a strength modulator, a second polarization controller, a polarizer, a second optical fiber, a single mode optical fiber, a photoelectric detector, an electric amplifier, an electric frequency mixer and a low pass filter. The up-conversion device can solve the problems of base band digital signal up-conversion in a radio over fiber system, the change, caused by dispersion, of microwave power along with microwave frequency and periodic damping, caused by the change of propagation length, of microwave power.

In an optical switch device, an optical control pulse is inputted into a nonlinear optical fiber in phase with each optical pulse of signal light which is to be outputted, so that the polarization directions of the optical control pulse and the signal light form a predetermined angle at the input stage of the nonlinear optical fiber, the optical control pulse causes polarization rotation and parametric amplification of the optical pulse in the nonlinear optical fiber, and then the optical pulse is outputted through a polarizer. The excitation level of the optical control pulse is set on the basis of the difference of a monitored output level of the optical pulse from a target level so that the output levels of optical pulses of the signal light are controlled at one or more desired levels.