Mode-locked Ytterbium Fiber Laser Research Articles

Rogue waves in a linear cavity Yb-fiber laser through spectral filtering induced pulse instability.

In this Letter, experimental observation of dissipative rogue waves (DRWs) due to spectral filtering induced pulse instabilities in a mode-locked ytterbium (Yb) fiber laser has been presented. A semiconductor saturable absorber mirror was used to mode-lock the linear cavity laser and a chirped fiber Bragg grating (CFBG) was used for dispersion management, which also acted as a spectral filter and output coupler. Under stable conditions, the cavity delivered dispersion managed dissipative solitons of 447fs duration and 0.69nJ pulse energy at 10.19MHz repetition rate with uniform intensity distribution over a long time span. As the spectral width increased with pump power, random intensity fluctuations were observed in the pulse train due to the filtering effect of the CFBG. Employing a dispersive Fourier transform by stretching the output pulse train in time allowed the existence of DRWs more than 4 times stronger than the significant wave height to be observed. Further increments of pump power led to a stable multi-pulsing state.

Passively Q-switched and mode-locked ytterbium fiber laser with Bi2S3 nanowire

In this paper, we report a passively Q-switched and mode-locked ytterbium fiber laser employing Bi2S3 nanowire as a saturable absorber (SA). The Q-switching and mode-locking can be achieved in the same cavity at the same pump power through carefully rotating the intra-cavity polarization controller. In the Q-switching experiment, the maximum output pulse energy is 157.2 nJ with a repetition rate of 22.26 kHz at pump power of 116.7 mW, while for passive mode-locking, the pulse train has a repetition rate of 3.94 MHz, pulse width of 782 ps and SNR ~49 dB. The laser wavelength of Q-switching and mode-locking are both centered at ~1038 nm, with 3 dB optical spectrum width of 0.3 nm and 0.2 nm, respectively. We show that Bi2S3 nanowire can be an efficient SA for an all-normal dispersion ultrafast ytterbium fiber laser.

Deep in vivo two-photon microscopy with a low cost custom built mode-locked 1060 nm fiber laser.

Here we demonstrate that a mode-locked ytterbium fiber laser for two-photon fluorescence microscopy can be built for $13,000. The laser emits at a wavelength of 1060 nm with a usable average power of 1 W at a repetition rate of 40 MHz and a compressed pulse width of 81 fs at the sample. The laser is used to obtain deep in vivo two-color images of layer-V pyramidal neurons expressing YFP and vasculature labelled with Texas Red at depths up to 900 µm. The sub-1 µm features of dendritic spines can be resolved at a 200 µm depth.

Tunable triple-wavelength mode-locked ytterbium fiber laser with birefringence filter

A mode-locked ytterbium fiber laser based on all normal dispersion (ANDi) technique and nonlinear polarization rotation (NPR) is investigated with birefringent plate as a spectral filter in this paper. Tunable triple-wavelength simultaneous operation is realized at central wavelengths of 1031.4, 1046.8 and 1066.5 nm, respectively. A maximum output power up to 161.4 mW is obtained at 1031.4 nm wavelength. By only changing the direction of the optical axis of the uniaxial birefringent filter, tunable range as wide as 19 nm is demonstrated. To the best of our knowledge, this is the widest tuning range and highest power reported so far for ANDi mode-locked ytterbium fiber lasers with triple-wavelength operation. Our analysis shows that the mechanism of the triple-wavelength mode-locked operation results mainly from the four-wave mixing in optical fibers; in addition, the wide gain bandwidth of Yb also plays a critical role for the stable oscillation of the third mode-locked wavelength. The energy conversion process governed by a set of four coupled equations is realized experimentally through the adjustment of the polarization controller, which is related to the phase matching.

Enhanced-locality fiber-optic two-photon-fluorescence live-brain interrogation

Two-photon excitation is shown to substantially enhance the locality of fiber-based optical interrogation of strongly scattering biotissues. In our experiments, a high-numerical-aperture, large-core-are fiber probe is used to deliver the 200-fs output of a 100-MHz mode-locked ytterbium fiber laser to samples of live mouse brain, induce two-photon fluorescence of nitrogen–vacancy centers in diamond markers in brain sample. Fiber probes with a high numerical aperture and a large core area are shown to enable locality enhancement in fiber-laser–fiber-probe two-photon brain excitation and interrogation without sacrificing the efficiency of fluorescence response collection.

High-power, fiber-pumped, picosecond green source based on BiB3O6

We report a stable, high-power, high-repetition-rate, picosecond green source at 532 nm in a compact and practical design based on single-pass second-harmonic generation (SHG) of a mode-locked ytterbium fiber laser in the nonlinear material BiB3O6. Using a 10-mm-long crystal, we have generated as much as 5.4 W of picosecond green radiation at 80 MHz for a fundamental average power of 14.2 W at a single-pass SHG conversion efficiency of 38%. The green output power exhibits excellent passive stability of 0.24% rms over 15 h, has a TEM00 spatial profile with M2 < 1.93, and a beam pointing stability <9 μrad over 1 h without active control.

Monolithic Fiber Mirror and Photonic Crystal Technology for High Repetition Rate All-Fiber Soliton Lasers

In this letter, we discuss the technology of a thin-film coating made with electron beam evaporation on a single-mode fiber end facet. A dichroic mirror made of ZrO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> and SiO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> was found to provide the necessary selectivity for 980-nm pump and 1040-nm signal wavelengths and enabled us to build a short-cavity mode-locked ytterbium fiber laser. Combined with a photonic crystal fiber dispersion compensator, it allows the realization of a 572-fs soliton all-fiber laser with a fundamental repetition rate of 571 MHz.

Sub-60-fs ytterbium-doped fiber laser with a fiber-based dispersion compensation

We present a mode-locked ytterbium fiber laser with a higher-order mode fiber compensating the group-velocity dispersion and partially the third-order dispersion of the single-mode fiber at a wavelength of 1 microm. The generated pulses had an energy of 0.5 nJ and could be dechirped externally to a pulse duration of less than 60 fs. The power spectrum shows a spectral full width at half-maximum of 57 nm.

On the possibility of observing bound soliton pairs in a wave-breaking-free mode-locked fiber laser

On the basis of numerical simulations, we explain the formation of the stable bound soliton pairs that were experimentally reported in a high-power mode-locked ytterbium fiber laser [Opt. Express 14, 6075 (2006)], in a regime where wave-breaking-free operation is expected. A fully vectorial model allows one to rigorously reproduce the nonmonotonic nature for the nonlinear polarization effect that generally limits the power scalability of a single-pulse self-similar regime. Simulations show that a self-similar regime is not fully obtained, although positive linear chirps and parabolic spectra are always reported. As a consequence, nonvanishing pulse tails allow distant stable binding of highly-chirped pulses.

Passively mode-locked ytterbium fiber laser utilizing chirped-fiber-Bragg-gratings for dispersion control

A robust, self-starting picosecond pulse source based on ytterbium (Yb3+) doped fiber laser is described. Utilizing a chirped-fiber-Bragg-grating (C-FBG) for dispersion control, solitary mode-locking is obtained without bulk dispersion compensation elements. A semiconductor saturable absorber (SESAM) is used for stable self-starting. 3.6ps pulses are produced, with 45MHz basic repetition-rate and mW scale average output power at 1060nm. Detailed numerical simulations based on the modified nonlinear Schrödinger equation agree well with the experimental results and are used as a design tool for the solitary mode-locked picosecond laser. The presented design can be simply employed in an all-fiber environmentally-stable system.

Fiber taper for dispersion management in a mode-locked ytterbium fiber laser

We exploit the large anomalous dispersion in the waist of a fiber taper to offset the intracavity normal chromatic dispersion of an Yb-doped fiber laser. The fiber taper provides sufficient anomalous dispersion to ensure soliton operation of the mode-locked laser. With the taper removed from the cavity, the laser operates in a net normal dispersion regime.

Semiconductor all-optical modulator for synchronization of independent fiber laser oscillators and active mode-locking

Using an optically driven nonlinear semiconductor mirror, we have synchronized a 1.56-/spl mu/m mode-locked erbium fiber laser to the pulse train from a mode-locked ytterbium fiber laser operating at 1.05 /spl mu/m. We demonstrate that a robust active or passive mode-locked picosecond pulse operation and tight control of the repetition rate can be obtained resulting in a large value of the locking tolerance for the slave laser cavity mismatch exceeding 250 /spl mu/m.

Environmentally-stable femtosecond ytterbium fiber laser with birefringent photonic bandgap fiber

We demonstrate an environmentally-stable mode-locked ytterbium fiber laser. The large birefringence of hollow-core photonic bandgap fiber allows it to control polarization in the laser while it provides the anomalous dispersion necessary for stretched-pulse operation. The laser generates 1-nJ pulses, which are dechirped to 70 fs.

Tunable, high-repetition-rate, harmonically mode-locked ytterbium fiber laser

We report a ytterbium fiber laser mode locked at its 281st harmonic, which corresponds to a repetition rate greater than 10 GHz. The laser produces linearly polarized, 2-ps pulses with up to 38-mW of average output power. The mode-locked pulses are tunable over a 58-nm window centered on 1053 nm.

1.05-�m mode-locked Ytterbium fiber laser stabilized with the pulse train from a 1.54-�m laser diode

Using cross-phase modulation in an optical fiber, we synchronized the pulse train from a mode-locked ytterbium fiber laser operating at 1.05 microm to an external optical master signal. The optical master source based on a 1.54 microm distributed feedback (DFB) diode laser was driven by the clock signal and was used as a seed source. The amplified seed pulses are launched into the fiber cavity and synchronize the mode-locked pulses through cross-phase modulation. The master clock signal is electronically generated, benefiting from inherent stability and repeatability. Due to its simplicity, this technique provides an attractive alternative to the traditional scheme that uses an independent mode-locked laser as source of seed signal. Since the approach is flexible and generally applicable, we expect this stabilization method to have a good potential for use in metrology and optical communications.

1.05-�m mode-locked Ytterbium fiber laser stabilized with the pulse train from a 1.54-�m laser diode: errata

Figures 2 and 4 have been altered during publication. Their correct version is presented herein.

Generation of 2-nJ pulses from a femtosecond ytterbium fiber laser.

We report a mode-locked ytterbium fiber laser that generates femtosecond pulses with energies as large as 2.2 nJ. This represents a 20-fold improvement in pulse energy compared with that of previously reported femtosecond Yb fiber lasers. The laser produces pulses as short as 52 fs, which are to our knowledge the shortest pulses to date from a Yb fiber laser. The laser is diode pumped by a wavelength-division multiplexing coupler, which leads to excellent stability.