174 results about "Pulse broadening" patented technology

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening/compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape wherein the laser gain medium further amplifying and compacting a laser pulse. The gain medium further includes a Ytterbium doped fiber for amplifying and compacting a laser pulse. The fiber laser cavity further includes a polarization sensitive isolator and a polarization controller for further shaping the output laser.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening/compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape wherein the wherein said laser gain medium further comprising a double cladding Ytterbium-doped Photonics crystal fiber (DC YDPCF) for amplifying and compacting a laser pulse. The fiber laser cavity further includes a polarization sensitive isolator and a polarization controller for further shaping the output laser.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening/compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape. The fiber laser cavity further includes a polarization controller controlled and driven by an electronically tunable driver tapping a small portion of an output laser of the fiber laser cavity to process and filtering the small portion of the output laser to drive the polarization controller to adjust a polarization state of a laser transmission in the laser system whereby the laser cavity is an electronically-tuned self-starting polarization-shaping mode-locked fiber laser.

The invention relates to a new method for measuring an ultrashort light pulse spectral phase in the field of information optoelectronics and a device thereof. According to the method, a time delay minus T with polarity is introduced between two quasi-monochromatic light components with frequency Omega generated by the chirped stretching of a pulse to be detected; an additional time delay plus T, which is introduced between two quasi-monochromatic light components due to a pulse stretcher, is compensated to be in synchronization with the pulse to be measured and generate two sum frequency lights together with the pulse through a sum frequency crystal; respective power spectra and coherent spectra without interference fringe are acquired through a spectrometer. The phase difference between the two sum frequency lights is calculated by the three spectra through formulae. A spectrum phase curve of the pulse to be measured is calculated by adopting a concatenated method. The method can accurately determine the phase difference polarity of the pulse spectrum, and provide the simple, real-time, rapid and accurate measurement method and the device thereof for measuring the ultrashort optical pulse spectral phase.

The invention relates to a method and a device for acquiring laser imaging echo waveform and level characteristics, a laser imaging device is adopted for transmitting laser pulse to a target, and a multi-echo time delay measurement unit and a maximum undistorted waveform collection unit of the device are utilized for respectively extracting multi-echo time delay data and full waveform data of the same transmitted pulse. The full waveform data is utilized for extracting the echo pulse broadening characteristic, the power characteristic, the waveform distribution characteristic and the like as target characteristics and saving in an echo pulse database. The multi-echo time delay data is utilized for generating a target multi-level point cloud image, and the echo power characteristic is further utilized for generating a target gray image. The method and the device fully utilize time delay, peak power and waveform information contained in echo pulse, and can not only obtain the target conventional point cloud image, but also realize the target multi-level imaging and the target gray imaging, generate the waveform characteristic database and achieve the purpose of acquiring the laser imaging echo waveform and level characteristics.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening/compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape.

A planar dispersion compensator for an optical signal is provided. The compensator decomposes an inputted optical signal into N component signals separated by a fractional wavelength deltalambda. Each component signal has its path-length adjusted to induce a sufficient phase shift between input and output to change the group delay of the optical signal when recombined from each of the component signals. In this manner, pulse broadening can be compensated by selectively varying the induced phase shifts to produce the desired level of opposite group delay.

The invention provides a seabed sediment reflectivity extraction method and system for laser radar sounding data. The method comprises: seabed echo waveform data included by airborne full-waveform laser radar sounding data are obtained and solution processing is carried out on the seabed echo waveform data based on a Richardson-Lucy deconvolution iterative algorithm to obtain an echo intensity and a seawater depth; according to a linear regression method, seabed echo waveform data solution is carried out to obtain sea water attenuation coefficient; echo intensity correction is carried out on a hot-spot effect caused by a seabed topographic slope and pulse broadening, thereby obtaining a slop of the seabed sediment and a seabed sediment reflectivity. According to the invention, the influence on the seabed echo intensity by various factors like a seawater attenuation coefficient, pulse broadening, and a hot spot effect are taken into consideration; and the seabed sediment reflectivity is inverted precisely.

The invention provides a single-shot laser pulse detection device. The single-shot laser pulse detection device comprises a detection light path for transmitting baseband detection light pulses, a reference light path for transmitting frequency-doubled reference light pulses, a dual-pulse generator for obtaining dual-pulses having a first time delay and transmitted collinearly along the reference light path, a light pulse converter for converting the dual-pulses into a series of dual-pulse form sub-pulses mutually delayed in time, separated from each other in space and propagated in parallel basically, a pulse stretcher for translating each frequency component of the baseband detection light pulses so as to stretch in the time domain, a dispersor for separating the frequency components in the baseband detection light pulses in space, and a plane detector for generating third-order mutual-correlation pulse signals from the baseband detection light pulses and the sub-pulses from the dispersor. The single-shot laser pulse detection device is capable of accurately measuring the waveform of the femtosecond petawatt lase pulses and solving the problem of difficult diagnosis of ultrafast and ultrastrong pulses large in dynamic range.

A programmable, ultrafast optical delay line based on reversible frequency conversion uses a time-prism pair and no moving parts. A first electro-optic phase modulator acting as a first time-prism shifts the frequency of an incoming pulse train. The pulse train passes through a dispersion element, such as a dispersive fiber, which delays the pulse train by an amount that is directly proportional to the magnitude of the frequency shift, which in turn is proportional to the magnitude of the phase modulator drive voltage. A second electro-optic phase modulator is driven π out of phase to the first modulator and restores the frequency of the delayed pulse train to the original frequency of the incoming pulse train. To reduce pulse broadening effects and enhance performance further, soliton propagation inducing elements can be employed between the time-prisms.

The invention relates to a method for achieving terahertz wave center frequency continuous adjustability through pulse laser widening. Initial pulse lasers are divided into base frequency light and frequency multiplication light. Time domain widening is carried out on the base frequency light by adopting a pulse widening method to obtain the base frequency light after the time domain widening. After the frequency multiplication light passes through a reflective mirror and a light beam time delay system, space beam combination is carried out on the frequency multiplication light and the base frequency light after the time domain widening, light of different wavelengths in the frequency light and the base frequency light interacts to generate terahertz waves of different frequencies, and the terahertz waves are received by a terahertz wave detection system. The relative time coincident point between the two pulses generated by the base frequency light and the frequency multiplication light can be adjusted freely through the light beam time delay system. In the practical operating process, the relative time coincident point between the two pulses can be changed simply by controlling the light beam time delay system in a frequency multiplication light path, and thus the central frequency of the terahertz waves can be adjusted. The method is suitable for ultrashort pulse lasers of various wavelengths.

The invention provides a once signal to noise ratio measuring method and a device based on a chirp pulse feature. The once signal to noise ratio measuring method and the device based on the chirp pulse feature can measure a signal to noise ratio of a once pulse. The principles include that a pumping probe light path is built by optical Kerr effect. The measuring device broadens probe light as chirp laser pulse in time and space by a grating or a prism. The probe light transmits from an analyzer due to the optical Kerr effect, a transmitted signal is collected by a scientific-level charge-coupled device (CCD), and signal to noise ratio of the laser pulse to be detected is obtained. The method introduces large negative dispersion amount by the grating or the prism, broadens probe light pulse to hundreds of picoseconds or more, and enables time window to reach hundreds of picoseconds or more. Meanwhile, a spatial light modulator is inserted in the probe light path so as to finally increase dynamic scopes.

A fiber laser cavity that includes a fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The fiber laser cavity further includes a positive dispersion fiber segment and a negative dispersion fiber segment for generating a net negative dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening-compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape wherein the laser gain medium further amplifying and compacting a laser pulse. The fiber laser cavity further includes a gain-flattening filter for flattening a gain over a range of wavelengths whereby the laser cavity is enabled to amplify a laser with improved pulse shape over the range of wavelengths.

Large effective area optical fibers are disclosed. In one embodiment, an optical fiber includes a glass core and a glass cladding surrounding and in direct contact with the glass core. The glass core may include a radius R_c from about 12 μm to about 50 μm; a graded refractive index profile with an alpha value greater than or equal to about 1.0 and less than about 10 at a wavelength of 1550 nm; and a maximum relative refractive index Δ_cMAX% from about 0.2% to about 0.75% relative to the glass cladding. An effective area of the core may be greater than or equal to about 150 μm² such that the core supports the propagation and transmission of an optical signal with X modes at a wavelength of 1550 nm, wherein X is an integer greater than 1 and less than or equal to 110. The glass cladding may include a maximum relative refractive index Δ_c1MAX% such that Δ_cMAX%>Δ_c1MAX%. The optical fiber has an RMS pulse broadening of less than or equal to about 0.15 ns/km at a wavelength of 1550 nm.

A planar dispersion compensator for an optical signal is provided. The compensator decomposes an inputted optical signal into N component signals separated by a fractional wavelength deltalambd. Each component signal has its path-length adjusted to induce a sufficient phase shift between input and output to change the group delay of the optical signal when recombined from each of the component signals. In this manner, pulse broadening can be compensated by selectively varying the induced phase shifts to produce the desired level of opposite group delay. Portions of the substrate of the planar waveguide are removed to improve thermal responsiveness of the path-length adjustment means.

A device generating supershort-superhigh laser pulse line of highly repeated frequency consists of self mode locking iiwaarite laser oscillator of mode locking pulse line, Faraday light isolator, aberration free laser pulse stretcher, regeneration amplifier of iiwaaeite, quantity selector of laser pulse, multistroke iiwaarite laser amplifier chain, gating pair pulse compressor in pumping laser and vacuum chamber. It is featured as exerting the first and the second DC high voltage signals on electrodes of Pochels box on amplifier, using a synchronous signal to control the first and the second DC high voltage source to work separately.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump, wherein the laser cavity further includes a normal dispersion fiber segment with a β″>0 where β″ representing a fiber dispersion, and an anomalous dispersion fiber segment with the β″<0 for generating a net anomalous dispersion for balancing a self-phase modulation (SPM) and a dispersion induced pulse broadening/compression in the fiber laser cavity for generating an output laser with a transform-limited pulse shape wherein the segment with the anomalous dispersion further includes a Photonic Crystal (PC), a Photonic Bandgap (PBG) or a higher order mode (HOM) fiber.

The invention discloses a switch cabinet partial discharge itinerant detector which comprises an ultrahigh frequency sensor, a cable and a detecting terminal, wherein the ultrahigh frequency sensor is connected with the detecting terminal through the cable. The detecting terminal comprises a signal conditioning unit, a data acquisition card and a touch screen. The signal conditioning unit comprises a band-pass filter, a signal amplifier and a pulse broadening device, wherein the band-pass filter, the signal amplifier, the pulse broadening device, the data acquisition card and the touch screen are connected in sequence. The switch cabinet partial discharge itinerant detector is compact in structure, convenient to carry and detect due to the fact that the detecting terminal is a handheld type, high in working efficiency and capable of effectively detecting the switch cabinet partial discharge by utilizing of an ultrahigh frequency detecting method.

An all-optical method of regenerating an optical return-to-zero format pulse signal of a first wavelength starts by introducing the input signal into a first end of a non-linear optical fiber to obtain a modified signal comprising pulses broadened in the wavelength domain. When this modified signal emerges from the second end of said non-linear optical fiber, a bandwidth slice is selected that is centered on a second wavelength so spaced from the first wavelength that its intensity is substantially unresponsive to weak pulses in the signal and relatively insensitive to intensity for other pulses. This slice is returned to the same non-linear optical fiber at its second end so that a further modified signal comprising pulses broadened in the wavelength domain will emerge from its first end. From this further modified signal a bandwidth slice centered on the first wavelength is selected as regenerated output. Regenerators operating in this way are also disclosed.

The invention discloses a single-fiber-type CARS excitation source device and realization method based on two-stage non-linear tuning. The device comprises a femtosecond fiber laser light source, an electric control light power attenuator, a first-stage tuner, a pulse broadening device, a second-stage tuner, a pump laser, a wavelength division multiplexer, a gain fiber, an optical filter and an output port. The femtosecond fiber laser light source outputs femtosecond pulses serving as Stokes optical pulses which enter the electric control light power attenuator; power control optical pulse wavelength tuning is realized in the first-stage tuner; the pulses are broadened to be femtosecond pulses through the pulse broadening device, and the femtosecond pulses then enter the gain fiber for amplification; signal optical pulses and idler frequency optical pulses are generated in the second-stage tuner, wherein the signal optical pulses serve as pump optical pulses of a CARS source; the optical filter filters the idler frequency optical pulses and the residual pump continuous light; and the rest optical pulses are output from the output port. Compared with the prior art, the device adopts a single-fiber light path structure and electric control tuning, and has the advantages of compact structure, anti-interference, high reliability and fast tuning speed; and CARS rapid imaging requirement is met.

A chirped pulse amplification (CPA) system comprises an optical pulse stretcher and an optical pulse compressor that are mismatched in that the optical pulse compressor includes a bulk optical grating while the optical pulse stretcher does not. High order dispersion compensation is provided by an optical phase mask disposed within the optical pulse compressor.

The invention provides an interference velocity measurement system and method, and belongs to the technical field of laser interference velocity measurement. The interference velocity measurement system comprises a chirped pulse generation device, a first optical fiber dispersion element, a detection device and a data processing device, and is characterized in that a part of chirped pulses with preset pulse width, which are generated by the chirped pulse generation device, is transmitted to the first optical fiber dispersion element so as to form reference light, and another part of the chirped pulses is incident on a target to be measured; chirped pulses reflected by the target to be measured are transmitted to the first optical fiber dispersion element so as to form signal light, frequency domain interference signals, which are formed by interference generated by the reference light and the signal light, are subjected to pulse broadening processing of the first optical fiber dispersion element and get into the detection device, and the detection device converts the frequency domain interference signals into electric signals and sends the electric signals to the data processing device. The interference velocity measurement system provided by the embodiment of the invention effectively reduces bandwidth requirements for the detection device used for recording the interference signals, and a time resolution and velocity measurement upper limit of the system is improved.

The invention relates to a flexible DC power distribution network monopolar grounding fault identification and fault protection method. Positive and negative DC bus voltage to the ground is acquired, and the interpolar voltage change rate of positive and negative DC buses is acquired; and when the absolute value of the interpolar voltage change rate of the positive and negative DC buses is greater than a first comparison limit, pulse broadens t1 millisecond and the absolute value of the sum of the positive DC bus voltage to the ground and the negative DC bus voltage to the ground is greater than a second comparison limit and the time of duration exceeds a time limit, the judgment result indicates a monopolar grounding fault. According to the method, the monopolar grounding fault bus can be rapidly identified, and rapid isolation of the fault bus can be realized by tripping the DC circuit breaker of the grounding fault DC bus so as to enhance the power supply reliability of a DC power distribution network.