273 results about "Chirp pulse" patented technology

By compensating polarization mode-dispersion as well chromatic dispersion in photonic crystal fiber pulse compressors, high pulse energies can be obtained from all-fiber chirped pulse amplification systems. By inducing third-order dispersion in fiber amplifiers via self-phase modulation, the third-order chromatic dispersion from bulk grating pulse compressors can be compensated and the pulse quality of hybrid fiber/bulk chirped pulse amplification systems can be improved. Finally, by amplifying positively chirped pulses in negative dispersion fiber amplifiers, low noise wavelength tunable seed source via anti-Stokes frequency shifting can be obtained.

Methods, devices and systems for generating ultrashort optical linear chirped pulses with very high power by amplifying the pulses so that their temporal duration is longer than the storage time of the amplifying medium. The additional gain factor is related to the ratio of the storage time to the stretched pulse. A preferred embodiment connects a mode locked laser source that generates optical pulses whose duration is stretched with a chirped fiber Bragg grating. Embodiments include methods, devices and systems causing an extreme chirped pulse amplifier (XCPA) effect in an oscillator.

Terahertz spectroscopy methods that are fast and have excellent spectral resolution and that do not require background correction of the instrument response without sample are disclosed. In one instance, the methods include phase coherent chirp pulse generation and phase coherent detection.

A modelocked fiber laser is designed to have strong pulse-shaping based on spectral filtering of a highly-chirped pulse in the laser cavity. The laser generates femtosecond pulses without a dispersive delay line or anomalous dispersion in the cavity.

A self-similarity mode locking optical fiber femtosecond laser device based on spectrum compression and amplification is composed of an optical fiber coupling output laser diode, a wavelength division multiplexing coupler, a ytterbium-mixed monomode optical fiber, an optical fiber frequency spectrum filter, a monomode optical fiber, an optical fiber collimator, a quarter-wave plate, a half-wave plate, a polarization splitting prism, a 45-degree reflector, a grating and an optical fiber isolator. Spectrum is compressed by using the self-phase modulation generated when negative chirp pulses are amplified in the ytterbium-mixed monomode optical fiber, narrow-band chirp-free picosecond pulses are formed, the optical fiber frequency spectrum filter is used for eliminating residual side lobes in nonlinear spectrum compression, self-similarity evolution is completed in the monomode optical fiber, broadband linear chirp parabola pulses are output directly, and Fourier transformation extremity femtosecond lasers are output after chirps are eliminated. The self-similarity mode locking optical fiber femtosecond laser device is high in efficiency, large in self-similarity evolution spectrum widening amount, capable of obtaining Fourier transformation extremity femtosecond laser pulses high in energy and narrow in pulse width, compact in structure and easy to operate.

A Quadrature Error Corrected Digital Waveform Synthesizer (QECDWS) employs frequency dependent phase error corrections to, in effect, pre-distort the phase characteristic of the chirp to compensate for the frequency dependent phase nonlinearity of the RF and microwave subsystem. In addition, the QECDWS can employ frequency dependent correction vectors to the quadrature amplitude and phase of the synthesized output. The quadrature corrections cancel the radars' quadrature upconverter (mixer) errors to null the unwanted spectral image. A result is the direct generation of an RF waveform, which has a theoretical chirp bandwidth equal to the QECDWS clock frequency (1 to 1.2 GHz) with the high Spurious Free Dynamic Range (SFDR) necessary for high dynamic range radar systems such as SAR. To correct for the problematic upconverter local oscillator (LO) leakage, precision DC offsets can be applied over the chirped pulse using a pseudo-random noise dither. The present dither technique can effectively produce a quadrature DC bias which has the precision required to adequately suppress the LO leakage. A calibration technique can be employed to calculate both the quadrature correction vectors and the LO-nulling DC offsets using the radar built-in test capability.

This invention relates to a super-short optical pulse measurement device based on the SPIDER technology, which applies a pulse dispersimeter with adjustable dispersion composed of two isosceles right-angle prisms of same size to generate chirp pulses, so that, this invention can test photo-pulses from several femtoseconds to several hundreds of femtoseconds, and the pulse dispersimeter is polarized and no light to incident photo-pulses and its dimension is not limited by the spectrum width of photo-pulses.

The present invention relates to a chirp pulse amplifying spectrum shaping dielectric film structure reflector, which comprises a transparent substrate, a high reflectance film system, an anaglyph structure and an external protective layer. Wherein, the high reflectance film system is composed of a plurality of staggered dielectric films. A high reflectance film layer and a lower reflectance film layer of the high reflectance film closely contact the anaglyph structure. The anaglyph structure can take a plurality of shapes, such as a micro-lens high transparency film system structure, an air dielectric structure, a glass anaglyph structure or other transparent dielectric structures, including semiconductor structures. As a high-power laser chirp pulse with a plane wave structure vertically casts onto the reflector, the laser passes through the high reflectance film system and the anaglyph structure and all residual lasers are reflected to back of the reflector through the transparent substrate. Reflex intensity distribution is modulated to a needed spectrum distribution structure. The reflector of the present invention can be inserted into any place of an amplifier link and improve capacity to distinguish shaping spectrum chromatic dispersion to a certain level. Scope modulation exceeds 60% without changing phase position, thus adapting to PW devices.

Disclosed is a technique for compensating for optical passband shift of an optical component (for example an optical demultiplexer). A broadband source coupled to a dispersive element generates a chirped pulsed optical signal. Data is modulated onto particular wavelengths of the chirped pulsed optical signal by appropriately synchronizing a data modulator. The modulated signal is transmitted to the downstream optical demultiplexer, which may be subject to passband shift due to, for example, changes in environmental conditions. A feedback signal from an output port of the demultiplexer is provided to the transmitter and is used to phase shift the modulator. The phase shift results in effectively adjusting the wavelength onto which the data is modulated to substantially correspond to the passband centers of the demultiplexer.

A pulse train comprising chirped pulses of electromagnetic energy can be used to excite a sample, such as for spectroscopic analysis. The respective chirped pulses can include a frequency sweep across a first specified bandwidth during a respective chirped pulse duration, the respective chirped pulse duration establishing a first frequency-domain comb peak separation. A width of a frequency-domain comb peak can be established at least in part by a total duration of the pulse train, and a bandwidth of the first frequency-domain comb can be determined at least in part by the first specified bandwidth of the frequency sweep of the respective chirped pulses.

The invention relates to a method and device to measure hertzhz pulse sequence by using chatter pulse-frequency spectrum. It includes ultrashort pulse light, first beam splitting sheet and grating pair. The ultrashort pulse light is a linear clatter pulse-frequency light. The polarizer and the second beam splitting sheet are on the reflecting direction of the first beam splitting sheet. A tested high speed light pulse frequency transmitting from the other direction of the second beam splitting sheet and the front direction is the second beam splitting sheet, non-linear crystal, the third beam-splitting sheet, analyzer and the first CCD spectroscope, the reflecting direction of the third beam splitting sheet would enter into the second CCD spectroscope. The invention is simple structure and is convenience to adjust.

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.

The invention discloses an optical fiber chirped pulse amplifier for ultra-short laser pulse output, which has the advantages of high pulse repetition rate, high power and ultra-short laser pulse output and belongs to the technical field of optical information. The optical fiber chirped pulse amplifier adopts an optical fiber type concave attenuating long-period fiber grating as a seed laser pulse of a high-power chirped femtosecond laser pulse amplifier or a spectral shaping component of a laser pulse amplified by a preamplifier, thereby eliminating the gain spectrum narrowing effect caused during amplification of the high-power chirped femtosecond laser pulse optical-fiber amplifier, increasing the spectral bandwidth of the amplified laser pulse. The laser pulse with smaller pulse width and higher peak power can be obtained through compression. The high-power chirped femtosecond laser pulse amplifier which has the advantages of high repetition rate, high power, simple structure and high efficiency and can be fully made of optical fiber is applicable to such industrial fields as precision machining, precision lithography, laser fusion and the like of semiconductor devices and metal materials and the basic scientific research such as biomedical imaging.

The invention relates to a spectral shaping device and a method of a chirp widening laser pulse. The spectral shaping device comprises a mode-locked laser, a raster stretcher, a lens, a pulse sample, an optical fiber splitter, an optical amplifier, a synchronous photoelectric converter, a shaping electrical pulse generator and an integrated guided-wave electro-optical modulator. The invention can perform the spectral pre-shaping of the chirp widening laser pulse before amplification, thus greatly decreasing gain narrowing effect in a chirp pulse amplification system. The spectral shaping device does not need complex light paths and machinery and spectral shape is easy to be changed. In addition, the spectral shaping device has flexible operation and high efficiency and is easy to be embedded into the multi-stage amplification system of the chirp pulse.

The invention discloses a chirp pulse compression method and a relative device, based on plasma, wherein the method comprises that (1), providing a section of plasma, (2), providing a first chirp pulse incident into the plasma, (3), providing a second chirp pulse incident into the plasma, (4), emitting the object chirp laser pulse along the direction same as the first chirp pulse into the plasma. And the device comprises a laser for emitting a laser chirp pulse, a light splitter for splitting the laser chirp pulse into two beams, while one beam via a split delay device is divided into a first chirp pulse an a third chirp pulse, and another beam via a pulse compressor forms a second non-chirp pulse, the first and the second chirp pulses are emitted to a plasma generated by a plasma generator, the second non-chirp pulse is reversed emitted into the plasma. The invention has high pulse compression efficiency and high light intensity damage threshold value.

The invention discloses a chirped pulse velocity interferometer. In the chirped pulse velocity interferometer, broadband laser pulses output by a broadband pulse laser light source are changed into linear polarization linear chirped pulses after passing through a polarizer and a pulse stretcher; polarization light S and polarization light P which are perpendicular in polarization direction are produced after the linear chirped pulses pass through a polarization splitting prism, and then the polarization light S and the polarization light P are successively emitted into the surface of a tested sample; the beat-wave interferometry is conducted on reflected light at a certain included angle, and produced beat-wave interferometric fringes are recorded through an imaging type spectrometer. A certain delay time difference exists before the polarization light S and the polarization light P are emitted into the surface of the sample, and synchronous transmission is achieved through optical path compensation after the polarization light S and the polarization light P are reflected by the surface of the sample. The oscillation penetrating direction of the polarizer is perpendicular to that of an analyzer. By means of the chirped pulse velocity interferometer, the time distinguishing of sub-picosecond scale can be achieved, the imaging type spectrometer serves as the corresponding recording system, an expensive streak camera recording system is avoided, and therefore the cost of a test system is effectively controlled.

The invention discloses a COTDR measurement method based on sub-chirped pulse extraction and relates to the technical field of optical fiber sensing measurement. The method comprises the steps of injecting a chirped pulse signal into a to-be-measured optical fiber and obtaining a coherent Rayleigh scattering signal of the chirped pulse signal; on the basis of the coherent Rayleigh scattering signal, obtaining coherent Rayleigh scattering responses of sub-chirped pulse signals through adoption of a sub-chirped pulse extraction algorithm; on the basis of the coherent Rayleigh scattering responses of the sub-chirped pulse signals, obtaining coherent Rayleigh scattering response patterns when the optical fiber is disturbed and when the optical fiber is not disturbed; and on the basis of the coherent Rayleigh scattering response patterns when the optical fiber is disturbed and when the optical fiber is not disturbed, obtaining optical fiber disturbance information through utilization of a suitable delay estimation algorithm. The invention also discloses a COTDR measurement system based on the sub-chirped pulse extraction. According to the method, a frequency sweeping process is replacedby a sub-chirped pulse extraction process and the Rayleigh scattering signal is obtained, so measurement speed and a measurement dynamic range of an optical fiber sensing system can be improved.

This invention discloses an optical signal modulation method, light transmitting method and its system in WDM light transmission system. The method is that multiroute chirp pulse light signals to be transmitted are combined, then to be transmitted by transmission fiber to be treated by dispersion compensation and optical amplification, further to be processed by splitting, and then to be received. This invention can allocate the radio relay transmission distance of tightly spaced WDM system of 10 Gbit/s and 100G intervals with the same link to increase the distances from original 400km to over 3000km and increase the transmission distances of 40Gbit/s and 100G intervals from 200km to above 1600 km.