260 results about "Mode locked fiber laser" patented technology

Frequency standards based on mode-locked fiber lasers, fiber amplifiers and fiber-based ultra-broad bandwidth light sources, and applications of the same.

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.

Femtosecond pump / probe experiments using short X-Ray and optical pulses require precise synchronization between 100 meter-10 km separated lasers in a various experiments. For stabilization in the hundred femtosecond range a CW laser is amplitude modulated at 1-10 GHz, the signal retroreflected from the far end, and the relative phase used to correct the transit time with various implementations. For the sub-10 fsec range the laser frequency itself is upshifted 55 MHz with an acousto-optical modulator, retroreflected, upshifted again and phase compared at the sending end to a 110 MHz reference. Initial experiments indicate less than 1 fsec timing jitter. To lock lasers in the sub-10 fs range two single-frequency lasers separated by several teraHertz will be lock to a master modelocked fiber laser, transmit the two frequencies over fiber, and lock two comb lines of a slave laser to these frequencies, thus synchronizing the two modelocked laser envelopes.

An improved method and apparatus for mode-locking a fiber laser at a pre-selected frequency wherein a doped fiber segment contains a narrowband FBG and an electro-optically tuned FBG, thereby making obsolete the need for an EOM to modulate the laser's wavelength. The present invention also provides a method and apparatus for mode-locking a fiber laser at a variable frequencies wherein a doped fiber segment contains two electro-optically tuned FBG's. The electro-optically tuned FBG may be fabricated by a thermal poling process.

An apparatus and method applicable for generating ultraviolet laser light having a wavelength in the 200-nm range and / or 250-nm range; in some embodiments, using a single fiber laser pump source (in some embodiments, a pulsed source). In some embodiments, the invention provides methods of generating 250-nm or 200-nm photons using a mode-locked 1000-nm fiber laser and efficient 4th / 5th harmonic frequency up-conversion. In other embodiments, the invention uses continuous wave (cw) single-frequency fiber lasers and external resonant frequency conversion. In still other embodiments, the invention uses cw single-frequency optically-pumped semiconductor lasers (OPSLs) and electrically driven vertical-cavity surface-emitting lasers (VCSELs) and externally resonant frequency conversion. All of these produce both of the ultraviolet wavelengths of interest.

A mode-locked fiber laser comprising a multicomponent glass fiber doped with a trivalent rare-earth ion of thulium and / or holmium and including a fiber-optic based passive saturable absorber that contains an adhesive material mixed with a saturable absorbing components and is disposed along the length of an optical fiber such as to assure that a mode propagating within the fiber spatially overlaps with the volume occupied by the saturable absorbing components.

A ring-cavity, passively mode locked fiber laser capable of producing short-pulse-width optical pulses at a relatively low repetition rate. The fiber laser uses a one-way ring-cavity geometry with a chirped fiber Bragg grating (CFBG) at its reflecting member. The CFBG is part of a dispersion compensator that includes an optical circulator that defines a one-way optical path through the ring cavity. A doped optical fiber section is arranged in the optical path and serves as the gain medium. A pump light source provides the pump light to excite the dopants and cause the gain medium to lase. A saturable absorber is operable to effectuate passive mode-locking of the multiple modes supported by the ring cavity. The ring cavity geometry allows to achieve mode locking with single pulse operation in a longer cavity length than conventional linear cavities. Furthermore, the longer cavity length reduces the constraints on the chirp rate of the CFBG. This, in turn, allows the CFBG to have a relatively high reflectivity, which provides the necessary dispersion compensation and cavity loss for generating short optical pulses at a low repetition rate.

Feedback loops can be used to shift and stabilize the carrier-envelope phase of a frequency comb from a mode-locked fibers laser or other optical source. Compared to other frequency shifting and stabilization techniques, feedback-based techniques provide a wideband closed-loop servo bandwidth without optical filtering, beam pointing errors, or group velocity dispersion. It also enables phase locking to a stable reference, such as a Ti:Sapphire laser, continuous-wave microwave or optical source, or self-referencing interferometer, e.g., to within 200 mrad rms from DC to 5 MHz. In addition, stabilized frequency combs can be coherently combined with other stable signals, including other stabilized frequency combs, to synthesize optical pulse trains with pulse durations of as little as a single optical cycle. Such a coherent combination can be achieved via orthogonal control, using balanced optical cross-correlation for timing stabilization and balanced homodyne detection for phase stabilization.

The present invention discloses a polarization relevant output multi-wavelength and passive mode-locking optical fiber laser which belongs to laser and light communication field. A ring laser cavity includes Er-doped fiber that is taken as gain medium; a 980nm / 1550nm wavelength-division multiplexer is used to couple pumping laser of 980nm into the Er-doped fiber; a polarization relevant isolator with tail optical fiber on two ends guaranties the laser work in one way, meanwhile plays the role of a polarizer; two polarization controllers respectively on two side of the polarization relevant isolator are used to control polarization state, a 10dB coupler with 10% of the terminal port used to output optical signal and 90% of the optical signal stays in the cavity for cycle. A segment of long single mode fiber is inserted in the laser cavity and used to increase nonlinear effect inside the laser cavity; a piece of polarization maintaining optical fiber and a polarization relevant isolator constitute a birefraction optical fiber periodicity filter; the optical fiber laser is provided with two different output modes, namely mode locking pulse output and multi- wavelength continuous wave output, and can adjust polarization and switch between the two output modes.

The invention relates to an ultra high-speed optical analog-to-digital conversion device. The ultra high-speed optical analog-to-digital conversion device comprises a high-speed pulse laser, a frequency spectrum broadening module, a repetition frequency multiplication module, an ultra wide band signal sampling module, a wavelength multi-channelizing module, parallel photoelectric conversion modules, parallel electric quantization modules and parallel data processing modules, wherein the high-speed pulse laser, the frequency spectrum broadening module, the repetition frequency multiplication module, the ultra wide band signal sampling module, the wavelength multi-channelizing module, the parallel photoelectric conversion modules, the parallel electric quantization modules and the parallel data tprocessing modules are sequentially connected. According to the ultra high-speed optical analog-to-digital conversion device, the high-speed pulse laser and the wavelength-division multiplexing technology are combined, while the advantages that the wavelength-division multiplexing technology is simple and practicable are kept, the defect that the output frequency spectrum of an active mode-locking fiber laser is narrow is overcome through the frequency spectrum broadening technology, high-speed photoelectric sampling is carried out through a broadband 1*2 electro-optical modulator, and by increasing the number of wavelength-division multiplexing channels or the number of parallel channels of the system, the bandwidth of a photoelectric detector and the sampling rate of an electric analog-to-digital converter are not increased while the sampling rate of the system is improved.

An apparatus for producing coherent pulsed light with a fiber-based master oscillator / fiber amplifier architecture includes a fiber-coupled mode-locked laser source. The fiber-coupled mode-locked laser source is configured to provide pulses having a pulse duration of less than 1 ns. The apparatus also includes a fiber-coupled amplitude modulator optically coupled to the fiber-coupled mode-locked laser source. The fiber-coupled amplitude modulator is capable of gate durations greater than 1 ns. The apparatus further includes a saturated fiber power amplifier optically coupled to the fiber-coupled amplitude modulator.

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 discloses a passive mode-locking fiber laser with a double-wavelength short pulse output. The invention has the characteristics of high stability, high efficiency, high power, high pulse repetition rate, synchronous passive laser impulse, single-line polarization, tunability, double wavelength and ultrashort pulse output. The ultrashort pulse fiber laser of the invention uses two polarization-preserving rare-earth doped (Er3+ / doped Yb3+) fibers as laser grain media, adopts a broadband polarization beam splitter spectrum and a broadband chirp polarization-preserving fiber grating and the like as cavity surface reflecting elements and chromatic dispersion compensation elements and utilizes a semiconductor saturable absorber as mode-locked elements and the like to achieve double-wavelength passive synchronous ultrashort pulse mode-locked fiber laser output. The passive mode-locking fiber laser with the double-wavelength short pulse output is a fiber laser with a novel structure of double-wavelength mode-locked ultrashort pulse output, which can achieve full-fiber.

The invention relates to a saturable absorber based on a plasmon axial vibration mode and belongs to the technical field of pulse laser. The invention particularly relates to a novel saturable absorber which consists of gold nanorods and film forming agent and can be used for mode-locked fiber lasers. The saturable absorber based on the gold nanorods can be prepared by adopting the method which comprises the steps of mixing the gold nanorod water dispersion and film forming agent water solution according to a molar ratio of (8-133):1, and performing ultrasonic dispersion for 2-5hours; and finally spin-coating the mixed solution on surfaces of flat silicon wafers and naturally drying the silicon wafers in a vacuum closed container till films are formed. The output of pulse laser at a near-infrared band is realized by using the unique longitudinal surface plasma resonance absorption characteristic of the gold nanorods. The saturable absorber based on the plasmon axial vibration mode enables the types of saturable absorbers to be expanded and can be widely used for mode locking of lasers at a visible-near infrared band.

The invention provides a sophisticated and constant temperature control experiment box and belongs to the technological field of electronic equipment. The invention consists of an incubator (10) and a constant temperature controller. The incubator (10) comprises an insulation component and a thermal transfer component; the constant temperature controller consists of a temperature setting circuit (1), a temperature measurement circuit (2), a subtraction circuit (3), a PI control circuit (4), a limiting protection circuit (5), a TEC drives circuit (VCCS) (6) and a display circuit (7). The invention has the stable performance and the reliable work; the temperature control accuracy is 0.1 DEG C; the short-term stability is plus or minus 2.6*10<-3> DEG C; the long-term stability is plus or minus 0.024 DEG C; the temperature range at the normal temperature is 10 DEG C to 40 DEG C. The invention can not only be used for providing a constant-temperature environment for active lock-mold fiber laser experiment, but also can be used for measurement and testing on small occasions and for detection of gradually changed weak signals.

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 mode locked fiber laser system is arranged to have a lasing bandwidth and having a linear cavity, the cavity including a gain medium, a saturable absorber having a saturation power, and a filter having a spectral response, wherein the mode locked fiber laser system is arranged so that substantial CW mode locked operation is obtainable with less than 3 times the saturation fluence impinging on the saturable absorber.

A fiber laser cavity that includes a laser gain medium for receiving an optical input projection from a laser pump. The mode-locked fiber laser further includes an all fiber based laser cavity including a dispersion management fiber segment for generating a negative (anomalous) to match a positive normal dispersion. The dispersion management fiber segment further coordinates with a polarization-controlling device for generating a polarization maintenance (PM) output laser pulse with a narrow pulse width.

The invention discloses a tapered fiber-based tunable dual-wavelength mode-locked fiber laser, which comprises a (2+1)*1 beam combiner, a thulium-doped fiber, a coupler, a polarization controller, a polarization independent isolator, a tapered fiber and a single-walled carbon nanotube which are sequentially connected end to end, wherein the (2+1)*1 beam combiner is also connected with a pump light source; the coupling ratio of the coupler is 10 to 90; the coupler comprises a 10% output port and a 90% output port in all; the 10% output port is connected to an output fiber; the 90% output port is connected to the polarization controller; the modulation period of the tapered fiber is 6.8-7.2nm; and the taper twist of the tapered fiber is 7.0-7.5microns. Through the tapered fiber with specific modulation period and modulation depth, the problem of laser mode competition is successfully solved by the tapered fiber; and output of tapered fiber-based tunable dual-wavelength mode-locked fiber laser light with a 2micron waveband is achieved.

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 invention belongs to the technical field of a laser, and provides a heterojunction saturable absorption mirror. The heterojunction saturable absorption mirror comprise a substrate, a heterojunction thin film for covering the substrate, and a protection film layer positioned on the heterojunction thin film, wherein the heterojunction thin film comprises at least two saturable absorption layers, and the materials of the saturable absorption layers are different. The invention also provides a preparation method for the heterojunction saturable absorption mirror, comprising the following steps of preparing the substrate and polishing the substrate; putting the substrate in a reaction chamber, and plating the at least two saturable absorption layers on a gold film layer in sequence by adopting a CVD method to form the heterojunction thin film; and plating the protection film layer on the surface of the heterojunction thin film. The heterojunction saturable absorption mirror provided by the invention is high in damage threshold value, simple in structure, low in cost, high in reliability, simple in preparation method and suitable for mass production.

The present invention describes a method to achieve stabilization of the repetition rate in a passive harmonic mode-locked fiber laser employing semiconductor saturable absorbers. The pulse organization is accomplished by electrically modulating the amplifier pump source that in turn optically modulates the saturable loss of semiconductor absorber. Moreover owing on an efficient modulation mechanism of the cavity loss, the method can be used to generate an actively mode-lock pulse train. The invention offers the advantages of an actively modulated mode-locked laser while maintaining the simplicity and the cost effectiveness of a passive mode-locked system. We expect that this approach combined with the use of regenerative modulation technique and polarization-maintaining fiber components will permit the generation of the dropout-free pulse trains at gigahertz repetition rates with good long-term stability and minimal cost.

The invention relates to a high repetition frequency harmonic wave mode locking fiber laser based on external continuous light injection, comprising a laser pumping source, a wavelength division multiplexing device, an optical isolator, a continuous light source, an optical coupler, a saturable absorber and a gain fiber, wherein the laser pumping source is connected to the pumping input terminal of the wavelength division multiplexing device, and the wavelength division multiplexing device is in connection with the optical isolator, and is then connected to the optical coupler together with the continuous light source; the optical coupler comprises a laser signal output terminal and a signal connection output terminal, wherein the signal connection output terminal is successively in connection with the saturable absorber and the gain fiber; the gain fiber is then in connection with the wavelength division multiplexing device; glowing ions are doped in the fiber core of the gain fiber. The high repetition frequency harmonic wave mode locking fiber laser has the characteristics of simple structure and low cost; through the combination between the continuous light source and a passive mode locking fiber laser, high repetition frequency harmonic wave mode locking is realized; in addition, outputted optical pulses possess the advantages of high repetition rate and narrow pulse width.

The invention relates to a passive mode-locked fiber laser device which includes a laser pumping source and a unidirectional annular resonant cavity. The unidirectional annular resonant cavity includes a wavelength division multiplexer, an Er doped fiber, a first optical-fiber collimator, a second optical-fiber collimator, a first 1 / 4 glass slide, a second 1 / 4 glass slide, a photoisolator, a bandpass filter, a polarization beam splitter and a 1 / 2 glass slide. The passive mode-locked fiber laser adopts nonlinear polarization rotation mode locking and utilizes the highly doped optical fiber as a gain medium so that the length of a laser cavity is reduced and the repeating frequency of the laser device is increased. Through introduction of the bandpass filter into the laser cavity, stray components and noises in the cavity are filtered so that clock jitter resulted from quantum noises is reduced. Through management of chromatic dispersion of the laser cavity, narrower pulses can be generated and wider frequency spectrum can also be obtained and intensity noises of the laser device are also reduced so that the passive mode-locked laser device is widely applicable to the field of optical-analog-digital system (OAD).

Compact laser systems are disclosed which include ultrafast laser sources in combination with nonlinear crystals or waveguides. In some implementations fiber based mid-IR sources producing very short pulses and / or mid-IR sources based on a mode locked fiber lasers are utilized. A difference frequency generator receives outputs from the ultrafast sources, and generates an output including a difference frequency. The output power from the difference frequency generator can further be enhanced via the implementation of large core dispersion shifted fibers. Exemplary applications of the compact, high brightness mid-IR light sources include medical applications, spectroscopy, ranging, sensing and metrology.

The invention belongs to the technical field of laser devices, and provides a high-power and tunable pulse fiber laser device and a super-continuum spectrum light source pumped through the high-power and tunable pulse fiber laser device. The high-power and tunable pulse fiber laser device sequentially comprises a tunable passive mode-locking fiber laser device based on the fiber nonlinear effect, a broadband fiber coupler, a power pre-amplification stage and a power main amplification stage in the light path direction. The output end of the high-power and tunable pulse fiber laser device is connected with photonic crystal fibers or high nonlinear fibers or other super-continuum spectrum generating fibers with zero-dispersion wavelength located in the pumping laser gain area, precise matching of the pumping laser and the zero-dispersion wavelength of the super-continuum spectrum generating fibers can be achieved, and accordingly, a broadband and high flatness super-continuum spectrum light source can be obtained. The device has the advantages that the structure is simple, the tuning of the pumping laser wavelength is convenient, cost is low, and full fiber is achieved, and the device can be applied to the fields such as biomedicine, remote sensing, environment monitoring, multi-channel fiber communication and spectroscopy.

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.

The invention discloses a tunable mode locking fiber laser based on a fiber grating and a grapheme. Tunable output of a linearity chamber fiber laser is realized based on a principle that a central wavelength of the fiber Bragg grating drifts along with strain linearity, and mode locking output of a linearity chamber fiber laser is realized based on a saturation absorption function of the grapheme with wide saturation absorption wave bands. The tunable mode locking fiber laser has advantages of full fiber structure, compact structure, stable performance, tunable broadband, wide application in the fields of fiber communication, fiber sensing, and the like and extensive applicability.

The invention discloses a method and a structure for precisely measuring the length of optical fibers, and belongs to the field of precision measuring instruments. The method is to measure the length of the optical fibers by utilizing the relation that the period of stable mode-locking pulse sequences generated by a passive mode-locking optical fiber laser is directly proportional to the length of a cavity of the laser. The structure consists of an erbium-doped optical fiber, a 980 / 1,550 nm wavelength division multiplexer, 980 nm pumping laser, a polarization dependent isolator, two polarization controllers and a 10 dB coupler. The optical fiber to be measured is connected with the laser through an optical fiber access port; the polarization controllers are adjusted to acquire stable fundamental-frequency mode-locking pulses; and the length of the optical fiber to be measured can be directly calculated by reading out the pulse period on an oscilloscope. The measurement precision of the method and the structure can reach centimeter order, and the method and the structure can be used for measuring the length of hundreds of kilometers of optical fibers.