Dissipative Soliton Resonance Pulses Research Articles

Efficient tunable cascaded Raman source with all-silica fibers based on 2-µm DSR pulse pumping.

We present an efficient tunable all-silica-fiber 2nd-order cascaded Raman pulse laser utilizing 2-µm dissipative-soliton-resonance (DSR) rectangular pulses for pumping and highly GeO2-doped silica fiber as Raman gain medium. When pumped at 1966.5 nm, the maximum 1st-order Raman optical conversion efficiency is up to 64.4% at 2153 nm, with 92.4% spectral purity and 0.39-W average power. The maximum 2nd-order Raman optical conversion efficiency is 19.3% at 2370 nm, with 39.2% spectral purity and 0.25-W average power. To our knowledge, these conversion efficiencies and spectral purities represent the highest levels achieved in a mid-infrared all-silica-fiber cascaded pulsed Raman laser. Additionally, by adjusting the central wavelength of the DSR seed pulse, the 2nd-order Raman light can be tuned within a range of 41 nm (2354∼2395 nm). Our system provides a simple and easy-to-implement solution for realizing efficient tunable cascaded pulsed Raman lasers in the 2.4-µm band.

Narrow-bandwidth picosecond dissipative soliton resonance in an all-anomalous-dispersion Er/Yb co-doped fiber laser

First, it is numerically demonstrated that narrow-bandwidth picosecond dissipative soliton resonance (DSR) pulses can be obtained in the all-anomalous-dispersion Er/Yb co-doped fiber (EYDF) laser, which is based on the nonlinear polarization rotation (NPR) mode-locking and narrow-band spectral filtering. The generated DSR pulses are characterized by a central peak on top of a rectangular pedestal temporally and two high-intensity spectral sidebands with less than 0.6-nm bandwidth. Second, the impacts of several key cavity parameters on characteristics of DSR pulses are investigated. Particularly, a new phenomenon of periodic evolution of the DSR pulse, featuring alternated high and low peak powers with the round-trips, is discovered by tuning filter bandwidth or net-cavity dispersion. Multi-pulse dissipative soliton (DS) and noise-like pulse (NLP) are also observed in the fiber laser. Finally, a 22.3-ps DSR pulse with 287.5-W peak power can be further compressed to 4.3 ps with 1126.5-W peak power by the dispersion compensation. This work further enriches the DSR pulse dynamics in the anomalous-dispersion region and paves a way to realize narrow-bandwidth picosecond DSR pulse fiber lasers.

Dissipative soliton resonance in a figure-eight multimode fiber laser.

We report, for the first time to the best of our knowledge, a spatiotemporal mode-locked (STML) multimode fiber laser based on nonlinear amplifying loop mirror (NALM), generating dissipative soliton resonance (DSR) pulses. Due to the complex filtering characteristics caused by the inherent multimode interference filtering structure and NALM in the cavity, the STML DSR pulse has wavelength tunable function. What's more, kinds of DSR pulses are also achieved, including multiple DSR pulses, and the period doubling bifurcations of single DSR pulse and multiple DSR pulses. These results contribute to further understand the nonlinear properties of STML lasers and may shed some light on improving the performance of the multimode fiber lasers.

Frequency-domain-resolved investigation of unitary h-shaped pulses.

We experimentally investigate the generation of h-shaped pulse in an all-polarization-maintaining (PM) and all-normal-dispersion (ANDi) mode-locked fiber laser. The generated pulse is demonstrated to be a unitary pulse, instead of a noise-like pulse (NLP). Furthermore, by employing an external filtering system, the obtained h-shaped pulse can be resolved into rectangular-shaped pulses, chair-like pulses, and Gaussian pulses. The authentic AC traces with a double-scale structure of unitary h-shaped pulses and chair-like pulses are observed on the autocorrelator. The chirp of h-shaped pulses is also proved similar to that of DSR pulses. To the best of our knowledge, this is the first time that the existence of unitary h-shaped pulse generation has been confirmed. Moreover, our experimental results reveal the close relationship of formation mechanisms of dissipative soliton resonance (DSR) pulses, h-shaped pulses, and chair-like pulses, which helps to unify the essences of such "DSR-like" pulses.

Multimode dissipative-soliton-resonance pulses in a Yb-doped fiber laser

Experimental observation of mode-locked dissipative-soliton-resonance (DSR) pulses, including single-mode DSR pulses and multimode DSR pulses, in a Yb-doped fiber laser is reported. DSR pulses in single-mode state and multi-mode state can exist at the same time and can be output stably. The multi-mode DSR pulses exhibit same linearly broadening characteristics and bell-shaped spectral shape as single-mode DSR pulses. The results would be beneficial for expanding the knowledge of nonlinear dynamics to multimode fiber lasers and provide new insights for DSR pulse output with a fully multimode structure to get larger pulse energy.

Efficient Raman pulse fiber laser pumped by a dissipative soliton resonance pulse near 2 µm.

A high-efficiency Raman conversion from 1.987 µm to 2.177 µm is demonstrated experimentally in 45 m GeO2-doped silica fiber, adopting a dissipative soliton resonance (DSR) rectangular pulse as the pump. Over the entire spectral distribution, the spectral purity of the first-order Raman pulse is up to 96.8%, suggesting a nearly complete pump depletion before the onset of cascaded Raman shifts. The corresponding pump-to-Raman conversion efficiency of 67.4% is the highest up to date in this spectral region. Meanwhile, a large Raman pulse energy of 1.03 µJ was obtained at the repetition rate near MHz level, corresponding to 0.893 W average power. In the total output, the Raman-dominated spike has a Full Width Half Maximum (FWHM) of 1.18 ns far narrower than DSR's pulse duration of 10.25 ns. The results indicate that DSR is a promising candidate for developing efficient Raman nanosecond pulse fiber laser in mid-infrared (MIR) region.

Nonlinear optical properties of carboxyl-functionalized graphene oxide for dissipative soliton resonance pulse generation

Here, we investigated the nonlinear optical (NLO) characteristics of carboxyl-functionalized graphene oxide (GO-COOH) in the near-infrared (NIR) region. The results revealed that GO-COOH samples exhibit strong saturable absorption at low pump levels and a gradual transition to reverse saturable absorption (RSA) with increasing pump power. Then the saturable absorber (SA) by depositing the GO-COOH on the side-polished fiber (SPF) was employed in Yb- and Er-doped fiber lasers. Stable ultrashort pulses operating in the dissipative soliton (DS) and conventional soliton (CS) regimes were obtained with pulse widths of 26.6 ps and 968 fs, respectively. Besides, the dissipative soliton resonance (DSR) phenomenon caused by the RSA of GO-COOH was also observed with increasing pump power. The high-stable DSR mode-locked pulses with the maximum pulse energy of 1.91 nJ and 0.74 nJ were obtained in YDFL and EDFL respectively. These results not only reveal the potentiality of GO-COOH in ultrafast photonics applications but also open a new avenue to explore high-pulse-energy laser sources based on two-dimensional materials.

Wavelength and repetition rate tunable high peak power dissipative soliton resonance in an all polarization maintaining Yb-doped fiber laser

High peak power dissipative soliton resonance (DSR) with tunable wavelength and flexible repetition rate is experimentally achieved based on an all polarization maintaining master oscillator power amplifier fiber laser. The figure-of-eight oscillator outputs DSR pulse at a fundamental repetition rate of 3.6 MHz with square-shaped temporal pulse duration of 600 ps. By adjusting the intracavity fiber filter, the center wavelength of the DSR pulse can be continuously changed from 1017 to 1042 nm. These wavelength and temporal duration tunable pulses are then coupled into an all-fiber pulse picker to gain another tuning freedom of repetition rate from 100 kHz to 3.6 MHz. Seeded by the flexible pulse, an two-stage all-fiber amplifier is used to boost the average power to 20 W with the polarization extinction ratio of 18.2 dB. After compression, a record pulse peak power of 1.91 MW is achieved at the repetition rate of 100 kHz with pulse duration of 55 ps.

Reverse saturable absorption in Ti3C2 MXene nanosheets for dissipative soliton resonance mode-locking operation in Er-doped fiber laser

In this paper, Ti3C2Tx MXene nanosheets were prepared using a low-power ultrasonic-assisted liquid phase exfoliation method. The Ti3C2Tx nanosheets based saturable absorber deposited on the tapered microfiber possessed the typical saturable absorption and reverse saturable absorption with the surface evanescent field. With a home-made femtosecond excitation source at 1550 nm, the modulation depth was determined as 4.8% with a saturation intensity of 18.7 MW/cm2. By inserting our as-prepared saturable absorber into an Erbium-doped fiber laser (EDFL), two types of mode-locked pulses operating in the stable conventional soliton (CS) and dissipative soliton resonance (DSR) regimes were realized at the fundamental repetition frequency of 7.39 MHz, respectively. The pulse width of the CS pulse was 1.185 ps with a central wavelength of 1560.6 nm. While the pulse width of the DSR pulses varied from 2.07 ns to a maximum of 8.13 ns with the increase of the pump power. Our work reveals the reverse saturable absorption effect of Ti3C2Tx could play a key role in the DSR pulse generation, which may benefit the application of the pulse modulation and optical communication with the two-dimensional materials.

Generation and vector features of pulsating dissipative-soliton-resonance pulses in a figure-of-eight fiber laser

Pulsation, as one of the most distinctive nonlinear phenomena, exists in versatile fields. Pulsating solitons in dissipative optical systems have received considerable research interest due to their wealthy nonlinear dynamics and potential applications. Here, we demonstrate the generation of pulsating vector dissipative-soliton-resonance (DSR) pulses in an ytterbium-doped fiber laser based on a nonlinear amplifying loop mirror, for the first time. By decreasing the pump power, the stationary DSR pulse in the cavity could evolve into the pulsating DSR one, which undergoes periodic variations in its width and energy. In contrast to the conventional pulsating behavior with pulse peak power modulation, the pulsating DSR pulse maintains its peak power unchanged due to the strong peak-power-clamping effect. By utilizing a high-speed oscilloscope, the single-shot polarization-resolved temporal evolution of pulsating vector DSR pulses is monitored. By appropriately adjusting the net cavity birefringence through the intra-cavity polarization controllers, two types of pulsating vector DSR pulses, including the pulsating group-velocity-locked DSR (GVL-DSR) and pulsating polarization-locked DSR (PL-DSR) states, are achieved in the laser cavity. It is found that the two orthogonally polarized components have synchronized pulsating behaviors, but their central wavelengths can be the same or different. Our results would shed new light on the dynamics of DSR pulses.

Dissipative soliton resonance and noise-like pulse in a self-pulsing fiber laser

In this paper, a self-pulsing Er-doped fiber laser operating in the dissipative soliton resonance (DSR) regime is firstly reported. By adjusting the pumping power and intracavity pulse polarization, the generated mode-locking pulse could evolve between soliton pulse, dissipative soliton resonance pulse and noise-like pulse (NLP). In the dissipative soliton resonance mode-locking regime, the generated rectangular-shaped pulses centered at 1570.5 nm with a maximum average output power of 20.6 mW and a pulse duration of 8.9 ns. Meanwhile, in the NLP regime, the maximum average output power is 49.9 mW, corresponding to a pulse energy of 2.5 nJ. The self-pulsing evolving dynamics can be analyzed using weak NPR effect by simultaneously considering the polarization dependent loss from the polarization controller and the reabsorption loss of the un-pumped gain fiber.

Improvement of peak power of dissipative soliton resonance pulse in a thulium-doped fiber laser

Single pulse energy and pulse width can be theoretically increased indefinitely without pulse-breaking in a dissipative soliton resonance pulse (DSR) generated from a mode-locked fiber laser when the peak power is keeping in a certain value. But in some applications, both high pulse energy and high peak power are needed in one single pulse. To improve the peak power of the DSR pulse, the characteristics of DSR pulses were investigated and found that the position of the gain fiber is a factor to influence the peak power and the pulse width. Here, we demonstrate a thulium-doped mode-locked fiber laser operating in the DSR regime with a nonlinear amplifying loop mirror (NALM). When changing the position of the gain fiber, the peak power of DSR pulse could be improved from 0.38 W to 1.42 W with the same pump power. This approach provides a method for increasing the pulse energy and efficiency in mode locked fiber lasers, which may meet some special application.

Harmonic Dissipative Soliton Resonance in an Er/Yb Co-Doped Fiber Laser Based On SESAM

Fundamental and harmonic mode-locking in the dissipative soliton resonance (DSR) regime is experimentally investigated in a net-normal-dispersion Er/Yb co-doped fiber laser based on the semiconductor saturable mirror (SESAM), where an equivalent narrow-band spectral filter is used for triggering multi-pulsing. By monotonically increasing the pump power with the fixed polarization controller (PC), the fundamental mode-locking operation of DSR pulses can be transformed into the harmonic mode-locking (HML) under the specific conditions. The main reason is the peak-power-clamping effect induced by the combined effects of the spectral filtering and saturable absorption of the SESAM at higher pump levels, which is applied to achieve the HML in the DSR regime for the first time. The DSR pulse broadens linearly with the pump power in a certain range, no matter whether it is in the fundamental mode-locking or HML state. By incorporating the dispersion compensation fiber (DCF) with different lengths, the pulse characteristics are discussed and compared in detail. The enhanced nonlinearity caused by increasing DCF length can lead to higher orders of HML pulses and even the generation of noise-like pulses (NLPs) with a long-enough DCF.

Dissipative-soliton-resonance and evolution in an all-normal dispersion Er-doped fiber laser

The generation of dissipative soliton resonance (DSR) in an all-normal dispersion erbium-doped fiber laser based on a real saturable absorber is amazing in both experiment and theory. However, it’s rarely to realize DSR in an all-normal Er-doped fiber laser in experiments to our knowledge. In this work, we analyze the principle of DSR generated in an all-normal dispersion erbium-doped fiber laser based on a real saturable absorber, and prove that the key reason is the reverse saturable absorption (RSA) effect of the real saturable absorber (SA). Then, we investigate the impacts of pump power, filter, and RSA coefficient in generating DSR pulse. In addition, when the saturable power of SA is above 25 W and the modulation depth of SA above 50%, a novel soliton explosion phenomenon based on RSA in DSR region is obtained for the first time to our knowledge. The work can be used for understanding the dissipative soliton resonance as well as the evolution in an all-normal dispersion Er-doped fiber laser. Furthermore, it also paves a way to realize high stable and high energy pulsed lasers in telecommunication region.

2.1 μm Band Dissipative Soliton Resonance Mode-Locked Ho-Doped Tunable Fiber Laser

We report a 2.1 μm band mode-locked holmium-doped fiber (HDF) laser with tunable wavelength and pulse width in dissipative soliton resonance (DSR) region for the first time to our knowledge. A piece of HDF is pumped by a home-made 1.9 μm band fiber source, and a nonlinear-amplifying-loop-mirror structure is used to realize mode-locking operation with net anomalous dispersion. The repetition rate of pulse is 8.97 MHz. The pulse duration can be adjusted from 1.16 to 3.93 ns with the increase of pump power, while maintains a constant peak power. At the maximum pump power of 2.1 W, the pulse energy is up to 2 nJ. Moreover, the central wavelength is in the tunable range from 2054.4 to 2076 nm by appropriately adjusting the polarization controllers. We also explore the nonlinear correlation characteristic of DSR pulse by changing the length of high nonlinear fiber.

Vector Staircase Noise-Like Pulses in an Er/Yb-Codoped Fiber Laser

We report on the experimental observation of vector staircase noise-like pulses (NLPs) produced by an Er/Yb-codoped fiber laser with a nonlinear optical loop mirror (NOLM) as the saturable absorber (SA). The staircase NLPs consist of two rectangular pulses with different energies and durations, such that the two pulse widths both increase linearly with increasing pump power with an almost constant slope while the pulse amplitude remains constant, similar to the case with Dissipative Soliton Resonance pulses. The polarization rotation state of the staircase NLPs has also been investigated along with multiple polarization dynamic patterns, including group velocity locked and polarization locked states. We have also observed harmonic mode-locked (HML) staircase NLPs by carefully adjusting the orientation of the intra-cavity polarization at fixed pump power. It was found that the HML staircase NLPs were identical to the fundamental staircase NLPs as regards the vector character and the changes in pulse duration. The experimental results are expected to enrich understanding of the vector nature of staircase NLPs and may lead to a new laser source for material processing.

Pulse Shape Estimation in a DSR Fiber Laser Using the Genetic Algorithm

Exploiting the computing power of the genetic algorithm, a numerical study of dissipative soliton resonance (DSR) in a ring laser mode-locked by a real saturable absorber (SA) is conducted. A section of photonic crystal fiber (PCF) is inserted into the laser cavity design to facilitate accurate control of both dispersion and nonlinearity. The influence of the cavity parameters on the evolution of the DSR pulses is systematically analyzed. The genetic algorithm demonstrates that the generation of DSR square pulses depends directly on the PCF dispersion, the PCF nonlinearity, the PCF length, and the modulation depth of the SA. Finally, the sensitivity of the DSR pulse width, peak power and energy to perturbations in a few key design parameters are highlighted.

High-power yellow DSR pulses generated from a mode-locked Dy:ZBLAN fiber laser.

Ultrafast yellow lasers are in high demand in recent biomedical and medical applications; however, direct emission of mode-locked pulses in yellow at the high-power level still presents a huge technical challenge to date. By integrating the nonlinear polarization rotation (NPR) scheme into a Dy:ZBLAN fiber laser, dissipative soliton resonance pulses at ∼575 nm are demonstrated for the first time, to the best of our knowledge. The average output power reaches ∼240 mW at maximum, which is an improvement of almost two orders of magnitude over those reported from the latest mode-locked visible fiber lasers. The laser scheme combines a piece of large-core Dy:ZBLAN gain fiber and free-space NPR components designated at the yellow bandwidth. The maximal pulse energy is 2.4 nJ at the repetition rate of ∼100 MHz and the minimal pulse duration is 83 ps. The achieved wavelength of 575 nm is the shortest ever reached from a fiber-based mode-locked laser to date.

Pulse shrinkage of dissipative-soliton-resonance pulses with or without period doubling

Dissipative soliton resonance (DSR) is a promising operation regime in fiber lasers where unlimited pulse energy boost is expected. However, several phenomena classified as anti-DSR performance were reported recently. Here pulse shrinkage of DSR pulses is investigated in a fiber laser. By setting a central-wavelength-drifting Gaussian filter, after DSR performance of pulse broadening with increasing gain, the pulse shrinkage occurs when the gain continues to increase. A central-wavelength-drifting bimodal filter can also achieve pulse shrinkage. In addition, pulse shrinkage together with period doubling can be observed by changing the initial settings.

Highly Efficient Multiple Watt Gain-Switched 1.7 μm All-Fiber Laser Pumped by 1.6 μm Harmonic Dissipative Soliton Resonance Pulses

Here, we firstly utilize a newly explored 1.6 μm harmonic dissipative soliton resonance (DSR) pulses as a pump source to realize a highly efficient gain-switched thulium fiber laser at 1719.52 nm. The 1.6 μm DSR pulses with a fundamental repetition rate of 360 kHz were produced from a nonlinear amplifying loop mirror (NALM) ring cavity, which directly output high power mode-locking pulses due to freedom of soliton-area limitation and pulse breaking. The harmonic mode-locking (HML) operation was achieved by properly adjusting the polarization controllers (PCs). The thulium fiber laser cavity constructed by a Fiber Bragg Grating (FBG) pair was resonantly (in-band) pumped by the 1.6 μm harmonic DSR pulses. Taking the merit of the strong absorption of Tm^3+ at 1.6 μm and the laser cavity having a low insert loss, the 1.7 μm gain-switched fiber laser with the maximum repetition rate of 2.16 MHz, corresponding to the average power of 2.826 W and the pulse energy of 1.33 μJ, was obtained at a high slope efficiency of about 71.9%. The maximum output power could exceed 3 W with a high slope efficiency of over 70%, which is the record in 1.7 μm all-fiber pulsed thulium lasers.