Yb-doped Fiber Research Articles

Nonlinear optical properties of lead halide perovskite CsPbBr3 for ultrafast pulse generation

Halide perovskites have attracted much attention in the field of nonlinear optics due to their strong quantum constraint, obvious exciton effect, and structural diversity. In this paper, lead halide perovskite CsPbBr3 nanocrystals were synthesized with a size of 50–100 nm. The prepared CsPbBr3 nanocrystals were deposited on the conical microfibers so that the nonlinear optical absorption features can be obtained. Based on a balanced twin-detector system, the modulation depth of the prepared CsPbBr3 nanocrystals was determined as 9.2% and 7.2% at 1 µm and 1.5 µm, respectively. When the CsPbBr3 saturable absorber (SA) was inserted into the Yb-doped fiber laser (YDFL), a stable noise-like pulse (NLP) mode-locking operation was obtained at a central wavelength of 1034 nm with a pulse duration of 415 fs. In the negative dispersive Er-doped fiber laser (EDFL), both the bound-state mode-locking operation with a pulse width of 971 fs and the conventional soliton mode-locking with a pulse width of 799 fs can be achieved at 1531 nm for the first time. These findings not only pave the way for a deeper understanding of the nonlinear optical properties in CsPbBr3 nanocrystals but also provide a solid platform for further exploration of applications in ultrafast photonics.

Multi-state broadband spectrum and ultra-short pulse spatiotemporal mode-locked Yb-doped multimode fiber laser

In the multimode fiber laser, a phenomenon of multi-state broadband spectrum and ultra-short pulse spatiotemporal mode-locking (STML) is obtained. The dissipative soliton, multiple pulses, harmonic pulse and bound soliton can be observed by rotating the polarization controllers(PCs). The spectral bandwidth of dissipative soliton is 19.04 nm at the central wavelength of 1039.40 nm, and the pulse width is 3.58 ps, acquiring the widest spectrum and the shortest pulse in an all-fiber dissipative soliton STML laser. As the STML state changes from dissipative soliton to bound soliton, spectral bandwidth decreases slightly. The spectral width and modulation period of the loose bound soliton with central wavelength of 1038.24 nm are 18.03 nm and 0.76 nm, respectively. We realize the conversion between the multiple states, which provides a scheme for the study of nonlinear soliton dynamics.

45 W kHz-linewidth single-frequency fiber laser at 1120 nm

Single-frequency fiber lasers (SFFLs) at 1120 nm have been widely used in biochemical analysis applications by generating 560 nm lasers. Here, we investigate the capacity of large-mode-area Yb-doped fiber for 1120 nm single-frequency laser amplification. By optimizing the length of large-mode-area Yb-doped fiber to balance the amplified spontaneous emission and stimulated Brillouin scattering effect, the output power of the 1120 nm SFFL could be enhanced to 45 W with a slope efficiency of 59.9%. At the maximum power level, the optical signal-to-noise ratio, the linewidth, and the beam quality of the output laser are 45 dB, 7.03 kHz, and M x 2=1.52/M y 2=1.49, respectively. Our study proves that using large-mode-area fiber in cooperation with a gain coefficient and fiber length optimization is promising to improve the output power of 1120 nm SFFL. And the experimental results provide implications for the expansion of Yb-doped single-frequency lasers to the wavelength above 1100 nm.

Near-complete extraction of maximum stored energy from large-core fibers using coherent pulse stacking amplification of femtosecond pulses

High field science relies on ultrashort pulse lasers with multi-joule pulse energies for studying light–matter interactions under extreme conditions and for driving particle accelerators and secondary radiation sources of x rays, gamma rays, neutrons, positrons, muons, and protons. Next-generation laser drivers will require a 103−104 times increase in pulse repetition rates, producing multi-joule energies at multi-kilowatt average powers to enable practical applications in nuclear engineering, advanced materials, medicine, biology, homeland security, and high-energy physics. Spatially coherently combined femtosecond fiber lasers are recognized as a pathway to these next-generation drivers, with significant practical advantages including high efficiency and the possibility of compact integration. However, chirped pulse amplification in fibers is capable of extracting only a small fraction (usually ∼1%) of the maximum stored energy. Here we demonstrate near-complete maximum stored energy extraction with low accumulated nonlinearity from a large-core fiber amplifier using coherent pulse stacking amplification. We have amplified a 81-pulse stacking burst in a 85 µm core chirally coupled core Yb-doped fiber, extracting up to 9.5 mJ (∼90% of stored energy) with <4.5 radians of accumulated nonlinear phase, temporally combined this burst into a single pulse, and achieved 4.2 mJ pulses of 313 fs bandwidth-limited duration after compression. This represents, to our knowledge, the highest energy extracted and compressed into a femtosecond pulse from a single fiber amplifier, enabling approximately two orders of magnitude size reduction of future high-energy coherently spatially combined fiber laser arrays.

Low-noise 2-GHz figure-9 fiber laser based on passive harmonic mode-locking.

We have proposed and demonstrated the generation of a high-repetition-rate ultrashort pulse with long-term stability and low noise based on a harmonic mode-locked (HML) figure-9 fiber laser. Different HML orders from the 2nd to the 13th are generated by adjusting the pump power, net dispersion, and wave plate angles. A 2-GHz HML pulse is obtained with a 155-MHz fundamental repetition rate in a Yb-doped fiber laser, and the corresponding supermode suppression level is as high as 50 dB. The average power of the output pulse is nearly 200 mW, and the compressed pulse duration is 535 fs. To the best of our knowledge, 2 GHz and 196 mW represent, respectively, the highest repetition rate and output power in a figure-9 fiber laser. This work offers a potential pathway to achieve high-repetition-rate ultrashort pulses in the GHz range with high power and low noise levels.

Multipulse bunches in the Yb-doped mode-locked fiber laser based on NLMMI-NPR hybrid mode locked mechanism

In this study, we propose a novel Ytterbium-doped ultrafast fiber laser based on nonlinear multimode interference-nonlinear polarization rotation (NLMMI-NPR) hybrid mode-locked mechanism. Stable single-pulse mode-locked state is achieved in the linear cavity, with a repetition rate of 12.8 MHz. By adjusting the polarization state and pump power inside the cavity, various characteristic modes are obtained, including multipulse bunches, second- and third-harmonic mode-locked states, second- and third-harmonic multipulse bunches states, and a chaotic multipulse state. This is the first exploration of multipulse bunches in Ytterbium-doped ultrafast fiber lasers based on the NLMMI-NPR hybrid mode-locked mechanism. And multipulse mode-locked fiber lasers have unique advantages in numerous fields owing to their higher energy and wider pulse width.

Influence of core coupling on spectral characteristics of 7-core Yb-doped fiber laser with fs-inscribed FBGs

Influence of core coupling on spectral characteristics of 7-core Yb-doped fiber laser with fs-inscribed FBGs

Observation of widely separated soliton molecules in a mode-locked Yb-doped fiber laser operating with net anomalous dispersion

This paper investigates the generation and characterization of soliton molecules (SM) in a semiconductor saturable absorber mirror (SESAM) mode-locked Yb-doped fiber laser with a linear cavity. By adjusting the pump power, both single-pulsing (SP) and double-pulsing (DP) states can be achieved. The observed soliton molecules are highly stable, with minimal temporal jitter despite being separated by 1.56ns. While SM have been observed in many different cavities this is one of the few reports in a Fabry–Perot cavity rather than a ring cavity and again most previous observations of soliton molecules having been in the anomalous dispersion regime. This configuration thus provides detailed and valuable insights into the behavior of SM, shedding light on their formation, stability, and dynamics. This study contributes to understanding long range soliton interactions in fiber lasers, with potential implications for applications such as multi-bit transmission, bit storage, and pump–probe experiments to study the dynamics of chemical reactions.

41.6nm/44 fs Mamyshev Yb-doped fiber laser with bound-state solitons and multiple harmonics

A circular Mamyshev Yb-doped fiber laser was experimentally designed, and multiple pulse modes, including single-pulse, bound-state pulse, and harmonic mode-locked pulse, were observed by modulating the seed source and pump power. Single-pulse mode-locking with a single-pulse energy of 68.6 nJ was demonstrated at a repetition frequency of 12.1 MHz with a spectral half-height width of 41.6 nm and a compressed pulse duration of 44 fs. Results were also obtained for bound-state and harmonic mode-locked pulses, both with post-compression pulse durations of less than 100 fs. The experiments provide validation of the dynamics of a wide range of pulses in Mamyshev lasers. These findings have implications for the further exploration and understanding of pulse dynamics within the optical domain.

44-fs, 1-MHz, 70-µJ Yb-doped fiber laser system for high harmonic generation.

We report the development of a robust Yb-doped fiber laser system based on chirped-pulse amplification (CPA), generating 44-fs laser pulses with up to 70-µJ pulse energy at a 1-MHz repetition rate. It consists of a Yb-doped nonlinear polarization evolution (NPE) mode-locked fiber oscillator, a chirped fiber Bragg grating (CFBG) stretcher, a wave-shaper for manipulating the spectrum of the signal, cascaded fiber amplifiers, and two compression units. The output pulse duration of 44 fs for efficient high harmonic generation (HHG) was achieved by a multi-pass multi-plate Herriott-type non-linear compression unit.

Figure-8 mode-locked Yb-doped fibre oscillator with a nonlinear amplifying loop mirror and power amplification

Abstract We report an all-polarization-maintaining Yb-doped fibre (YDF) femtosecond (fs) laser source at ∼1 µm comprising a figure-8 mode-locked oscillator and two YDF amplifier stages. By employing a nonlinear amplifying loop mirror, we could achieve dissipative soliton mode-locking with an output of 24.6 mW at a repetition rate of 6.2 MHz. In our experiments, a Raman signal of 16% in the pulse energy helps to obtain stable mode-locked operation in the figure-8 oscillator. The dissipative soliton pulse from the oscillator is stretched by a chirped fibre Bragg grating and is amplified by a two-stage YDF amplifier. After compression, the YDF master-oscillator power-amplifier system yields fs pulses with a pulse energy of 2.3 µJ and a pulse duration of 274.6 fs at a repetition rate of 0.52 MHz. The output pulse energy is limited by the third-order nonlinearity of the fibre amplifier chain. Prospects for further pulse energy scaling are discussed.

Widely wavelength-tunable high-repetition-rate femtosecond pulse source with highest average power up to 28 W

We have proposed and demonstrated a high-repetition-rate ultrashort pulse fiber amplification system based on a wavelength-tunable oscillator. This fiber amplification system produces an average power exceeding 20 W in bursts of 200 pulses with a 578 MHz intra-burst pulse repetition rate and a 1 MHz burst repetition rate. The center wavelength of the amplified pulses can be tuned from 1030 to 1080 nm. By utilizing pre-chirp management nonlinear amplification technique, the achieved shortest pulse duration is 27 fs with an average power of 25 W at 1032 nm. For all the amplified pulses with different wavelengths, the pulse duration after optimal compression is below 60 fs. To the best of our knowledge, this is the first time that a widely wavelength-tunable high-power laser with a repetition rate exceeding 100 MHz and a pulse duration of several tens of femtoseconds has been realized. Additionally, using only common double-cladding Yb-doped fiber as the gain fiber, without any large-mode-area Yb-doped photonic crystal fiber or rod-type Yb-doped fiber, makes the system compact and reliable due to the simple fusion operation.

Cutting speed and behaviors of ice using Yb-doped fiber laser

The use of a laser to cut or drill ice has been proposed and demonstrated multiple times in previous decades as a novel, but never adopted, machining tool in glaciology and paleoclimate studies. However, with the rapid development of high power fiber-laser technology over the past few decades, it is timely to perform further studies using this new tool. An investigation is made herein on the cutting of ice using a Yb-doped fiber laser emitting at a wavelength of 1070 nm, the most extensively developed and highest power fiber laser technology, in pulsed and continuous-wave operation. Visible-light observations of clear tap water ice samples, moving at a constant velocity relative to a pulsed laser beam, demonstrate a linear relationship between the duration of a millisecond-range laser pulse and the depth of the meltwater-free cut formed in response. Thermal imaging of the irradiated face shows that peripheral heating trends linearly for pulse lengths greater than 5 ms. A comparison of pulse trains with a constant time-averaged power suggests that shorter pulses are advantageous in slot-cutting efficiency and in minimizing visible alterations in the surrounding ice. These results demonstrate the viability of powerful fiber-compatible lasers as a tool for ice sample retrieval and processing.

Development of an ultrafast laser system based on a Yb-doped fiber and a Yb:YAG thin-rod for the preclinical study of pigmented lesions treatment using a Hartley guinea pig.

In this research, we developed an ultrafast laser system based on a Yb-doped fiber oscillator and Yb:YAG thin-rod amplifier to investigate the efficacy of the laser for the treatment of pigmented lesions. The developed laser exhibited an output power of 22.7 W, center wavelength of 1030 nm, repetition rate of 495 kHz, pulse energy of 45.9 µJ, and pulse duration of 1.56 ps, respectively. For a compact and stable chirped pulse amplification system, a chirped fiber Bragg grating (CFBG) stretcher and a chirped volume Bragg grating (CVBG) compressor, both with fixed dispersion, were used. The dispersion of the total laser systems was precisely compensated by adjusting the length of the passive fiber and utilizing the self-phase modulation effect of the fiber amplifier. The developed ultrafast laser system was then applied in preclinical studies for the treatment of pigmented lesions in a guinea pig model. Three colored squares, each measuring approximately 15 × 15 mm, were treated by scanning a focused beam with varying laser fluences ranging from 0.5 to 2 J/cm2, using wavelengths of 515 nm and 1030 nm. The colorimeter measurements, which were performed 1-5 weeks after laser treatment, indicated that the laser was effective in reducing pigment, particularly black and blue pigments at higher fluences. This research represents the first trial of a preclinical study on pigmented lesions using an ultrafast laser system with a pulse duration below 10 ps, shorter than the stress relaxation time of 10 nm melanin granules. The results are meaningful as they offer valuable insights into the effectiveness of ultrafast laser therapy.

Less is more: surface-lattice-resonance-enhanced aluminum metasurface with giant saturable absorption for a wavelength-tunable Q-switched Yb-doped fiber laser

Resonant metasurfaces provide a promising solution to overcome the limitations of nonlinear materials in nature by enhancing the interaction between light and matter and amplifying optical nonlinearity. In this paper, we design an aluminum (Al) metasurface that supports surface lattice resonance (SLR) with less nanoparticle filling density but more prominent saturable absorption effects, in comparison to a counterpart that supports localized surface plasmon resonance (LSPR). In detail, the SLR metasurface exhibits a narrower resonance linewidth and a greater near-field enhancement, leading to a more significant modulation depth (9.6%) at a low incident fluence of 25 μJ/cm2. As an application example, we have further achieved wavelength-tunable Q-switched pulse generation from 1020 to 1048 nm by incorporating the SLR-based Al metasurface as a passive saturable absorber (SA) in a polarization-maintaining ytterbium-doped fiber laser. Typically, the Q-switched pulse with a repetition rate of 33.7 kHz, pulse width of 2.1 μs, pulse energy of 141.7 nJ, and signal-to-noise ratio (SNR) of greater than 40 dB at the fundamental frequency can be obtained. In addition, we have investigated the effects of pump power and central wavelength of the filter on the repetition rate and pulse width of output pulses, respectively. In spite of demonstration of only using the Al metasurface to achieve a passive Q-switched fiber laser, our work offers an alternative scheme to build planar, lightweight, and broadband SA devices that could find emerging applications from ultrafast optics to neuromorphic photonics, considering the fast dynamics, CMOS-compatible fabrication, and decent nonlinear optical response of Al-material-based nanoplasmonics.

Compact mid-infrared dual-wavelength optical parametric oscillator pumped by Yb-doped fiber lasers based on two PPMgLN crystals

A compact mid-infrared (MIR) dual-wavelength optical parametric oscillator (OPO) pumped by Yb-doped fiber lasers (YDFLs) based on dual-crystal with an L-shaped cavity structure is demonstrated. Two periodically poled MgO-doped lithium niobite (PPMgLN) crystals with polarization periods of 30.44 μm and 28.96 μm are pumped by two YDFLs, respectively. The dual-wavelength output at 3.45 μm and 4.00 μm is obtained synchronously by adjusting the double pump power. When the total power of double-end pumping is 28.98 W with a ratio of 2:3, the pulse width is 60.80 ns under the repetition frequency of 110 kHz, the output power is 1.483 W@3.45 μm and 1.703 W@4.00 μm, respectively. The total conversion efficiency is 10.99%. By utilizing this cavity structure, the gain and wavelength tuning of the two OPOs can be controlled separately. Meanwhile, the pulse width is 46.93 ns@3.45 μm and 39.38 ns@4.00 μm, respectively. The laser beam quality closely approaches the theoretical quality of the fundamental mode beam. Additionally, by independently adjusting the temperature of the two PPMgLN crystals from 20 °C to 150 °C, tunable mid-infrared laser outputs with wavelengths of 3.448–3.272 μm and 4.006–3.864 μm are achieved. The corresponding tuning bandwidths are 176 nm and 142 nm, respectively.

Nonlinear Absorption in 2D Ruddlesden-Popper Perovskites: Pathways to Ultrafast Optical Applications.

Owing to their distinctive photophysical properties resulting from their larger exciton binding energy and the influence of dielectric and quantum confinement effects, considerable research interest has been directed toward two-dimensional Ruddlesden-Popper halide perovskites (2D RP-HPs). Particularly, 2D RP-HPs exhibit exceptional multiphoton absorption (MPA) effects that reveal versatile applications. In this work, two-photon absorption (2PA) and three-photon absorption (3PA) in 2D RP-HPs, specifically (PEA)2PbBr4 and (BA)2PbBr4 platelets, have been demonstrated through their photoluminescence spectra under multiphoton excitation, revealing a power law relationship with excitation energy. On the other hand, polarization-dependent MPA measurements are also conducted to obtain their anisotropy properties. The excellent 2PA and 3PA effects of 2D RP-HPs have found applications in ultrafast optics to construct fringe-resolved autocorrelation traces, enabling the retrieval of pulse duration not only passively mode-locked Ti:sapphire at 800 nm but also Yb-doped fiber lasers at 1030 nm.

Self-starting mode-locking in an all-PM Yb-doped fiber laser oscillator enabled by a 3x3 nonlinear optical lossy loop mirror: erratum.

This erratum corrects an error in Fig. 4 of the original publication [Opt. Express31, 42136 (2023)10.1364/OE.505449] caused by incorrect values of the vertical axis in logarithmic scale. The correction does not influence the conclusions of the original article, nor does it impact any parameter of the laser oscillator.

Tunable multi-wavelength all polarization-maintaining hybrid mode-locked Yb-doped fiber laser

We demonstrate an all polarization-maintaining (all-PM) mode-locked ytterbium-doped fiber laser (YDFL) based on a semiconductor saturable absorber mirror and nonlinear polarization evolution. The laser can produce tunable dual-wavelength from 1019.75 nm to 1038.68 nm, and triple-wavelength from 1021.28 nm to 1038.35 nm. To our knowledge, this is the first report of tunable dual- and triple-wavelength mode-locked operation in all-PM mode-locked YDFL. Furthermore, numerical simulations have demonstrated the multi-wavelength genesis and dynamic evolution. Our research proposes an innovative approach to achieving tunable multi-wavelength in all-PM fiber laser and lays the groundwork for a new type of all-PM tunable stabilized laser source.

Orthogonally polarized dual-wavelength Pr:LiYF4 lasers in 1.3 μm region

We report a continuous-wave (CW) orthogonally polarized dual-wavelength Pr:LiYF4 laser in 1.3 μm region pumped by a Yb-doped fiber laser. The gain and loss of the wavelengths in the orthogonally polarized directions were balanced by an inclined etalon inserted into the cavity. At an absorbed pump power of 9.2 W, a dual-wavelength laser operating at 1310 nm in π-polarization and 1326 nm in σ-polarization with 2.26 W of total output power was achieved. Moreover, by continuing to adjust the tilt angle of the etalon, the three other pairs of dual-wavelengths (1289 and 1306 nm, 1289 and 1306 nm, and 1306 and 1310 nm) were also obtained. The output power ratio of each pair of dual wavelengths was nearly 1:1. To the best of our knowledge, this is the first work realizing the Pr:LiYF4 laser operating in 1.3 μm region.