693 results about "Mode-locking" patented technology

In one aspect the invention relates to a frequency varying wave generator. The generator includes a gain element adapted to amplify a wave having a wavelength; a time varying tunable wavelength selective filter element in communication with the gain element, the tunable filter element adapted to selectively filter waves during a period T; and a feedback element in communication with the tunable filter element and the gain element, wherein the tunable wavelength selective filter element, the gain element and the feedback element define a circuit such that the roundtrip time for the wave to propagate through the circuit is substantially equal to a non-zero integer multiple of the period T.

Integrated wired and wireless wavelength division multiplexing passive optical network (WDM PON) apparatus using a light source mode-locked to fed incoherent light includes: a fed light generator for providing fed light for up/downstream signals via a broadband light source emitting an incoherent optical signal; a central office (CO) for receiving, mode-locking, and downstream-optical-transmitting the incoherent optical signal generated by the fed light generator and receiving and optical-detecting an upstream optical signal transmitted from a subscriber unit; and the subscriber unit for receiving, mode-locking, and upstream-optical-transmitting the incoherent optical signal generated by the fed light generator and receiving and optical-detecting a downstream optical signal transmitted from the CO, wherein a wired optical transmitter for transmitting a baseband wired signal and a wireless optical transmitter for transmitting a high frequency radio frequency (RF) signal are comprised for up/downstream optical transmission of the CO and the subscriber unit.

A laser utilizes a cavity design which allows the stable generation of high peak power pulses from mode-locked multi-mode fiber lasers, greatly extending the peak power limits of conventional mode-locked single-mode fiber lasers. Mode-locking may be induced by insertion of a saturable absorber into the cavity and by inserting one or more mode-filters to ensure the oscillation of the fundamental mode in the multi-mode fiber. The probability of damage of the absorber may be minimized by the insertion of an additional semiconductor optical power limiter into the cavity. To amplify and compress optical pulses in a multi-mode (MM) optical fiber, a single-mode is launched into the MM fiber by matching the modal profile of the fundamental mode of the MM fiber with a diffraction-limited optical mode at the launch end, The fundamental mode is preserved in the MM fiber by minimizing mode-coupling by using relatively short lengths of step-index MM fibers with a few hundred modes and by minimizing fiber perturbations. Doping is confined to the center of the fiber core to preferentially amplify the fundamental mode, to reduce amplified spontaneous emission and to allow gain-guiding of the fundamental mode. Gain-guiding allows for the design of systems with length-dependent and power-dependent diameters of the fundamental mode. To allow pumping with high-power laser diodes, a double-clad amplifier structure is employed. For applications in nonlinear pulse-compression, self phase modulation and dispersion in the optical fibers can be exploited. High-power optical pulses may be linearly compressed using bulk optics dispersive delay lines or by chirped fiber Bragg gratings written directly into the SM or MM optical fiber. High-power cw lasers operating in a single near-diffraction-limited mode may be constructed from MM fibers by incorporating effective mode-filters into the laser cavity. Regenerative fiber amplifiers may be constructed from MM fibers by careful control of the recirculating mode. Higher-power Q-switched fiber lasers may be constructed by exploiting the large energy stored in MM fiber amplifiers.

The present invention provides pulsed lasers which employ carbon nanotubes, particularly layers of carbon nanotubes, as saturable absorbers, mode lockers or for Q-switching elements. The present invention also provides methods and materials for mode-locking and Q-switching of lasers in which carbon nanotubes are employed as non-linear optical materials and/or saturable absorbers which facilitate mode-locking and/or Q-switching. The invention further provides mode locker and Q-switching elements or devices which comprise one or more layers containing carbon nanotubes which layer or layers function for mode locking and/or Q-switching.

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.

A high-power coherent array of Vertical Cavity Surface Emitter Lasers is described in which a plurality of Vertical Cavity Surface Emitting Lasers (VCSELs) are provided along with a structure which optically couples each of the VCSELs the plurality of VCSELs to one another by a predetermined amount to cause a coherent mode locking condition to occur. The coupling structure can be a beam cube, a plurality of smaller bean cubes, or a waveguide/grating system, for example. A reference source, or controlled coupling among the VCSELs, is used to phase lock the VCSELs to one another.

A mode-locked laser that has an optical cavity containing multiple optical amplifiers, each dedicated to a respective spectral portion of an optical signal generated by the laser, wherein the dispersion effects are managed by utilizing a separate intra-cavity phase tuner for each such spectral portion and/or by having appropriately configured waveguides corresponding to different spectral portions. Advantageously, a relatively wide combined gain spectrum provided by the optical amplifiers and the intra-cavity dispersion compensation provided by the phase tuners and/or waveguides enable this laser to realize a mode-locking regime that results in the emission of an optical pulse train having a relatively wide frequency spectrum. In one embodiment, the optical cavity of the mode-locked laser has a perfectly spectrally sampled arrayed waveguide grating (AWG) that is configured to divide the optical signal into the spectral portions and apply these portions to the respective waveguides, optical amplifiers, and phase tuners.

A laser resonator includes an OPS gain-structure that is pumped with optical pulses repeatedly delivered at a pulse-repetition frequency corresponding to a resonant frequency of the laser resonator. The laser resonator additionally includes a passive mode-locking arrangement such that the resonator delivers mode-locked optical pulses. In one example the laser resonator further includes a CW optically pumped OPS gain-structure for increasing the power of the mode-locked pulses delivered from the resonator.

A CS optical pulse train generation method, which is able to change the half width of an optical pulse constituting a CS optical pulse train, and which is compact and has low power consumption. A distributed Bragg reflector semiconductor laser utilized in this method is one which is constituted comprising an optical modulation region, a gain region, a phase control region, and a distributed Bragg reflector region. Current is injected into the gain region by way of a p-side electrode and a n-side common electrode by a constant current source, forming the population inversion required for laser oscillation. Optical modulation required to manifest mode locking is carried out in the optical modulation region. A diffraction grating is formed in the distributed Bragg reflector region. A CS optical pulse train with a repetitive frequency of f_rep is generated by adjusting the effective indices of both the phase control region and the distributed Bragg reflector region such that, of the longitudinal modes of the mode-locked semiconductor laser diode, the two longitudinal modes close to the frequency f₀, which is the Bragg wavelength of the distributed Bragg reflector region converted to a frequency, become f₀+(f_rep/2) and f₀−(f_rep/2).

The invention relates to a two-dimensional stratified material based practical saturable absorber and a production method thereof, and belongs to the field of saturable absorbers of lasers. The two-dimensional stratified material based practical saturable absorber comprises a substrate, a high-reflection layer, a saturable absorption layer and a functional layer. One end face of the functional layer is connected with the saturable absorption layer, one end face of the saturable absorption layer is connected with the high-reflection layer, and one end face of the high-reflection layer is connected with the substrate. By the two-dimensional stratified material based practical saturable absorber and the production method thereof, application of the lasers, such as Q-switching, mode locking and optical signal processing, is realized. By the high-reflection layer formed by composite materials, absorption loss is reduced and reflection rate is increased, and optimal material combinations can be found in terms of different wave lengths.

The invention discloses an optical frequency domain reflection-distributed vibration frequency sensing and locating device and a demodulation method. A technical method of optical frequency domain reflection beat frequency interference of a self-injective mode locking laser of a linear turning ultra-narrow linewidth whispering gallery mode is adopted in the optical frequency domain reflection-distributed vibration frequency sensing and locating device. The optical frequency domain reflection-distributed vibration frequency sensing and locating device comprises a main interferometer which is used to obtain a sensing signal and an auxiliary interferometer of a clock trigger signal. The demodulation method comprises that wavelength domain information is obtained by the main interferometer, fast Fourier transform is used to transform the wavelength domain information, and then distance domain information is obtained. A group of static reference signals and a group of vibration signals are collected. The distance domain information, namely local distance domain information, is selected in sequence by moving windows. Complex number cross correlation is used on the static signals and the vibration signals of the local distance domain information on each position. According to a noise coefficient of the complex number cross correlation, a position of a vibration point is obtained. A subsidiary summit position of the complex number cross correlation of the local distance domain information on the position of the vibration is picked up, and the subsidiary summit position is vibration frequency information.

A semiconductor surface emitting optical amplifier chip utilizes a zigzag optical path within an optical amplifier chip. The zigzag optical path couples two or more gain elements. Each individual gain element has a circular aperture and includes a gain region and at least one distributed Bragg reflector. In one implementation the optical amplifier chip includes at least two gain elements that are spaced apart and have a fill factor no greater than 0.5. As a result the total optical gain may be increased. The optical amplifier chip may be operated as a superluminescent LED. Alternately, the optical amplifier chip may be used with external optical elements to form an extended cavity laser. Individual gain elements may be operated in a reverse biased mode to support gain-switching or mode-locking.

The invention relates to a practical saturable absorption device based on black phosphorus and belongs to the field of saturable absorption devices of laser devices. The practical saturable absorption device based on the black phosphorus is formed by combining four layers of materials or mutual combining three layers of the four layers of materials or combining the four layers of materials combined mutually and functional insertion layers added on the upper portion and the lower portion of the four layers of materials at will or combining the saturable absorption layers and any one layer of materials or combining the saturable absorption layers, and each saturable absorption layer comprises at least one of a black phosphorus film, black phosphorus nano lamella particles, black phosphorus ramifications and functionalization black phosphorus. According to the practical saturable absorption device based on the black phosphorus, the application of Q regulation and mode locking of the laser device, optical signal processing and the like is achieved, and more importantly, the effect that the modulation depth can be flexibly regulated by giving play to the property of the black phosphorus is achieved.

The invention relates to a passive mode-locking ultrashort pulse all-fiber laser with a waveband of 2.0 microns and belongs to the field of a laser technology and nonlinear optics. The passive mode-locking ultrashort pulse all-fiber laser with the waveband of 2.0 microns mainly comprises a laser pumping source, a pumping combiner, thulium-doped or thulium-holmium-codoped rear earth doped fibers, a circulator, a saturable absorber, a laser beam splitter, an isolator, a fiber bragg grating, a polarization controller and the like. The thulium-doped or thulium-holmium-codoped rear earth doped fibers are used as a gain medium; the saturable absorber is used as a passive mode-locking device; and the output of an ultrashort laser pulse which is in the waveband of 2.0 microns and has high pulse energy is realized. Due to the adoption of the all-fiber structure design, the passive mode-locking ultrashort pulse all-fiber laser with the waveband of 2.0 microns has the advantages of simple structure, high environment stability and the like, and the industrialization application is easy to realize.

The invention relates to an erbium doped fiber laser with multi-wavelength and mode locking functions and convertible working state and a realization method thereof, in particular to a laser which can realize switching conversion between multi-wavelength and mode locking, has adjustable output wavelength position of multi-wavelength, and can stably work at room temperature and a realization method thereof. The laser comprises: a gain amplification unit, a polarization control unit, an output coupling unit, a comb filtering unit, an optical isolation unit and a nonlinear fiber loop mirror. The realization method of the laser includes the following steps: incident polarization state and double refraction are adjusted to lead the nonlinear fiber loop mirror inserted in the cavity of the laser to be in different working states, and the multi-wavelength and mode locking functions of the laser are respectively realized according to the different working conditions of the nonlinear fiber loop mirror. The invention has the advantages of convenient toning, low cost, being capable of realizing the two functions of stable multi-wavelength continuous output and mode locking pulse output, and the like, and can satisfy the demand for multifunctional laser light sources of optical time division multiplex/wavelength division multiplex communication technology.

A laser device (100), configured for generating laser pulses, has a laser resonator (10) with a gain disk medium (11) and a Kerr medium (12). The laser resonator (10) includes a first mode shaping section (13) which is adapted for shaping a circulating electric field coupled into the gain disk medium (11), and a second mode shaping section (14), which is adapted for shaping the circulating electric field coupled into the Kerr medium (12) independently of the electric field shaping in the first mode shaping section (13). Furthermore, a method of generating laser pulses (1) using a laser resonator (10) with a gain disk medium (11) and a Kerr medium (12) is described.

The invention discloses a 2-micrometer high-pulse energy thulium-doped optical fiber laser of a hybrid pump. The 2-micrometer high-pulse energy thulium-doped optical fiber laser comprises a first fiber grating, a first fiber beam combiner, a second fiber beam combiner, a gain fiber and a second fiber grating, which are connected in sequence, wherein a first pumping source is connected with a second input end of the first fiber beam combiner through a first optical isolator, a second pumping source is connected with a second input end of the second fiber beam combiner through a second optical isolator, the first fiber gating and the second fiber gating form a laser resonance cavity, the first pumping source is a continuous laser diode, the second pumping source is a pulsed laser, and the gain fiber is a thulium-doped fiber. The 2-micrometer high-pulse energy thulium-doped optical fiber laser is reduced in the threshold valve energy of a pumping pulsed light in a gain switch technology, is capable of obtaining pulse with higher energy compared with other laser pulse producing technologies such as regulating Q and mode locking, has the characteristics of full-fiber connection, simple structure and the like, and brings convenience for application and popularization.

The invention discloses a double-coating large-mode-area photon crystal flysecond laser directly obtaining micro joule-level single pulse energy, belonging to the field of laser technique and nonlinear optics, where the laser main body is based on double-coating large-mode-area photon crystal optical fiber of polarization-protection structure and adopts high-power LD laser to directly pump; the laser uses grating pair to compensate dispersion, starts mode locking with the help of semiconductor saturable absorber mirror (SESAM), and controls polarization by wave plate and polarization beam splitter and implements tunable output; laser resonant cavity keeps net positive dispersion inside and runs in self-similar mode locking mode and outside-cavity dispersion compensation is made on the output pulse and the pulse is 100-200fs wide. And the advantages: the laser has good stability, and the output pulse has high energy and high repeating frequency. And the invention can effectively avoid split of pulse running at high energy.

The invention provides a resonant cavity for outputting mode-locking picosecond laser and a mode-locking picosecond laser device. The mode-locking picosecond laser device comprises a pumping source, a focusing lens and the resonant cavity for outputting the mode-locking picosecond laser, and the pumping source, the focusing lens and the resonant cavity are sequentially arranged along a light path. The resonant cavity is characterized that a laser crystal, a focusing device, a Fabry-Perot etalon and a semiconductor saturable absorber mirror are arranged in the resonant cavity, and the energy density of light beams acting on the semiconductor saturable absorber mirror can be sufficient to realize continuous mode-locking owing to the focusing device. Peak power of the picosecond laser device can be accurately controlled, so that different application requirements can be effectively met advantageously. Besides, pulse width of the picosecond laser device can be controlled, so that different application requirements can be effectively met advantageously. In addition, picosecond pulse width can be tuned, operation is easy, and mode-locking stability is unaffected. A pulse width tunable device is small in size and is beneficial to saving space.

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.

The invention discloses an all-fiber pulsed laser, and belongs to the field of laser technology and nonlinear optics. The all-fiber pulsed laser includes a pump source (1), an optical combiner (2), a first gain fiber (3), a second gain fiber (4), a first reflective fiber Bragg grating (5), a second reflective fiber Bragg grating (6), an optical isolator (7), a full reflection mirror (8) and a circulator (9), and adopts a structure of linear cavity or annular cavity. By use of the rare earth-doped gain fibers as a laser modulator, with no additional external modulation source and an all-fiber structure, ultrashort pulse laser output of high stability, high power, high energy and high efficiency is achieved. Compared with a semiconductor saturable absorption mirror (SESAM) and graphene (Graphene) modulation Q, mode-locking technology, the all-fiber pulsed laser employs gain fiber for direct pulse modulation, has the advantages of simple design, compact structure and high stability, and is easier to industrialize.