Er-doped Fiber Laser Research Articles

Similariton-like Pulse Evolution in an Er-Doped Fiber Laser with Hybrid Mode Locking

An Er-doped all-fiber ultrashort pulse laser with positive total net-cavity group-velocity dispersion is demonstrated based on a hybrid mode-locking mechanism ensured by single-walled carbon–boron–nitrogen nanotubes with coaction of the nonlinear polarization evolution effect. The generation regime with a similariton-like spectrum is obtained. The spectrum width is ~31.5 nm, and the minimal pulse duration is ~294 fs at full width at half maximum. The average output power is ~3.2 mW, corresponding to 0.376 nJ pulse energy and 1.25 kW peak power. The fundamental pulse repetition rate is ~8.5 MHz, with a signal-to-noise ratio of 60 dB. The standard deviation of average output optical power stability, measured for 12 h, is about ~1% RMS, and the maximum level of relative intensity noise (RIN) does not exceed <−120 dBc/Hz in the 30 Hz–1 MHz frequency range. To prove the similariton-like regime generation, we also studied numerically and experimentally the pulse evolution during propagation through a laser resonator and output single-mode fiber with anomalous dispersion.

Passively mode-locked fiber laser based on ethylene glycol

A passively mode-locked Er-doped fiber laser employing ethylene glycol as a saturable absorber (SA) has been proposed and experimentally validated. The ethylene glycol-SA is fabricated by filling the space between the end facets of two optical patch cords inserted into a cannula with ethylene glycol. Utilizing such an SA with a modulation depth of 9.6 %, stable mode-locking operation are manifested in the laser cavity, including the production of bright pulse and bright-dark pulse pair. The generated bright pulse has a center wavelength at 1562.28 nm, a 3 dB bandwidth of 0.21 nm, a repetition frequency of 20.24 MHz, and a signal-to-noise ratio (SNR) of 57 dB. Through precisely manipulating the polarization state and the pump power in the laser cavity, the bright-dark pulse pairs can be successfully attained at the same repetition frequency. This is the first demonstration of a passively mode-locked fiber laser utilizing ethylene glycol as the saturable absorber. Due to their superior optical absorption characteristics, low cost, simplicity in fabrication and non-volatile nature, ethylene glycol-SAs have enormous potential in the field of nonlinear optics and ultrafast photonics.

Passively Q-switched Er-doped fiber laser based on carbon-doped silver nanoparticles saturable absorber prepared using laser ablation method

In this work, we investigate the effect of carbon-doped silver nanoparticles on the Q-switched performance of erbium-doped fiber laser (EDFL). The carbon-doped silver nanoparticles were synthesized using a laser ablation method. The prepared nanoparticles were inserted between fiber ferrules using the adhesion process of the index-matched gel. Incorporating a saturable absorber inside the laser cavity initiates a stable Q-switched mechanism at 11.2 mW of threshold power. The measured results demonstrate that as the pump power of EDFL increases from 11.2 to 267 mW, the pulse repetition, and pulse width tuned from 21.33 to 95.2 kHz and 13.3–3.18 µs, respectively. At 267 mW of pump, the maximum average output power, pulse energy, and peak power were further measured to be 2.36 mW, 24.68 nJ, and 7.76 mW, respectively. Besides, the stability and threshold characteristics of EDFL based on carbon-doped silver nanoparticles were further explored. This study shows that the synthesis of metal nanoparticles using the laser ablation technique and their implementation as saturable absorber represents a promising avenue for advancing ultrafast laser technologies with improved stablility, efficiency, and tunability.

Modeling the 3-Micron Class Er-Doped Fluoride Fiber Laser With a Cubic Energy Transfer Rate Dependence

Modeling the 3-Micron Class Er-Doped Fluoride Fiber Laser With a Cubic Energy Transfer Rate Dependence

L-band of ∼ 1.6 μm tunable multi-wavelength mode-locked Er-doped fiber laser with an MMF- FMF based structure

1.6 μm tunable mode-locked fiber laser are mainly used in the biomedical field, laser processing, and other aspects, have excellent application prospects. We propose a novel MMF-FMF-based device, which acts both as a saturable absorber and a wavelength selection filter. The reduction of insertion loss caused by FMF affects the laser gain competition process, leading to changes in gain allocation and bandwidth allocation. The laser generated stable mode-locked pulses with a repetition frequency of 23.23 MHz at pump powers exceeding 51 mW. By adjusting the angle of the fiber optic squeezer with the PC, successfully achieved switchable single-, dual-, and triple-wavelength lasing outputs, as well as tunable single- and dual-wavelength lasing outputs. The wavelength-tuning ranges for the single- and dual-wavelength lasing outputs were 31 nm (1570 nm-1601 nm) and 24 nm, respectively. The accurately adjustable L-band novel mode-locked fiber laser exhibits enormous potential for application.

Metallic layered VSe2 saturable absorber based single- and dual-wavelength ultrafast fiber laser

Vanadium selenide (VSe2) is a special two-dimensional (2D) transition metal dichalcogenide (TMD) material with metallic properties similar to graphene, which has been proved to have saturable absorption properties and used in mode-locked fiber lasers. As an excellent saturable absorber (SA) material, VSe2 has advantage of ultrafast carrier recovery time and broadband optical response range. However, the potential application of VSe2 in the field of ultrafast photonics has not been fully developed so far. In this work, the as-prepared VSe2 nanosheets were deposited on tapered fiber by optical deposition to obtain VSe2 SA. By inserting VSe2 SA into an Er-doped fiber laser, the mode-locked pulses with a central wavelength of 1574.4 nm can be obtained. The pulse width of the laser is measured to be ∼680 fs which is narrowest in the reported VSe2 SA-based lasers. In addition, the unique dual-wavelength mode-locked pulse is also obtained by further adjusting intracavity dispersion and polarization. This kind of dual-wavelength pulse is valuable in high order harmonic generation enhancement, terahertz wave generation, dense wavelength division multiplexing, dual-frequency comb and other applications. Our results show that metallic VSe2 is of great potential value in ultrafast fiber laser.

Generation of high energy 780 nm femtosecond pulses by frequency doubling of an all-polarization-maintaining Er-doped fiber laser

We demonstrate a high-energy 780 nm wavelength band femtosecond laser by utilizing single-pass frequency doubling all-PM Er-doped fiber amplifier (EDFA) in a periodically-poled lithium niobate (PPLN) crystal. The high power 1560 nm laser is realized based on chirped pulse amplification (CPA) technology, which has obtained the average power of 3.02 W, repetition frequency of 1.03 MHz, and pulse width of 640 fs. Subsequently, by using a PPLN crystal as frequency doubling element, a maximum output power of 0.46 W with 620 fs pulse width at 780.29 nm is generated, the corresponding pulse energy is 0.44 μJ and the peak power is 0.71 MW. To the best of our knowledge, the 0.44 μJ laser output in 780 nm wavelength band is the highest pulse energy generated from a frequency doubling femtosecond Er-doped PM fiber laser.

Generation of stable femtosecond pulses using MoS2−xSex as the saturable absorber in Er-doped fiber laser

A new transition-metal dichalcogenide (Janus TMDs), molybdenum selenide sulfide (MoS[Formula: see text]Se[Formula: see text]), has attracted wide attention due to its unique and highly stable alloy structure, high carrier mobility and the ability to modulate the band gap based on composition. In this work, MoS[Formula: see text]Se[Formula: see text] nanosheets were prepared through liquid phase exfoliation and further prepared as a saturable absorber (SA). The nonlinear optical response was investigated by the homemade balanced twin-detector measurement system, revealing the potential of MoS[Formula: see text]Se[Formula: see text]-SA in ultrafast photonics. The SA devices exhibited good saturation absorption characteristics. By applying it to the Er-doped fiber laser, a stable mode-locked fiber laser based on MoS[Formula: see text]Se[Formula: see text]-SA was successfully achieved. The pulse width was measured to be 509 fs, with a spectral width of 6.33 nm and a maximum output power of 7.44 mW in the mode-locked state. This is the first reported instance of achieving mode-locking operation in the Er-doped fiber laser using MoS[Formula: see text]Se[Formula: see text]-SA, indicating its great potential for applications in ultrafast photonics.

Germanene: demonstration of the conversion from mode-locked to Q-switched mode-locked in Er-doped fiber laser

Some two-dimensional layered mono-elemental materials have been reported as saturable absorbers (SAs) for the generation of various soliton phenomena, and many excellent results have been achieved. In our experiment, we made thin films of germanene-polyvinyl alcohol (Ge-PVA) and applied them as SA in Er-doped fiber lasers, investigated Ge’s characteristics, and demonstrated the conversion from mode-locked to Q-switched mode-locked (QML). The conventional mode-locked operation with a repetition rate of 9.63 MHz and a central wavelength of 1559.7 nm was stably triggered when the pump power exceeded the threshold of 40 mW. QML pulse with a central wavelength of 1530.26 nm and the maximum pulse energy of 86 nJ can be obtained by changing the pump power and polarization state of the light in the cavity. This work reveals the excellent optical properties of Ge SA in ultrafast fiber lasers and provide a new approach for the generation of QML pulses.

Implementation of Er-doped random fiber laser self-mixing sensor with ultra-limit sensitivity

This study first demonstrates that the random distributed feedback fiber laser (RDFL) can be implemented for sensing detection by using the self-mixing effect as a sensing mechanism. By constructing a compact self-mixing velocimeter based on Er-doped RDFL with the integration of a laser, sensing element, and transmission platform, we successfully measured the minimum detectable feedback intensity of 38.65 fW for the velocity signal, corresponding to 0.55 photons per Doppler cycle, exhibiting ultra-high sensitivity dynamics characteristics. In addition, the velocity measurement of a non-cooperative target at a single-channel distance of 100 km is accomplished because of the natural feature of long-distance transmission for the random distributed feedback fiber lasers, which greatly improves the ultra-long detection range in the field of self-mixing sensing. The proposed sensing scheme not only unveils a fresh perspective on the exploration of random fiber laser sensing but also showcases its diverse and wide-ranging applications within the realm of remote sensing measurements.

The generation of noise-like pulses and various solitons with CuO nanorods as a broadband saturable absorber

Copper oxide (CuO) nanorods exhibit unique photoelectric properties due to their high surface area, excellent volume effect, and quantum confinement effect, which have also attracted wide attention in the application of ultrafast photonics. In the present work, CuO nanorods were successfully prepared by a simple synthesis strategy and characterized in detail. The density of electron states (DOS) and the band structure of CuO were predicted by the first principles simulation method. The nonlinear optical response parameters of CuO nanorods were determined by a twin-balanced detector system. Based on the excellent nonlinear optical response, CuO nanorods were exploited as saturable absorbers (SAs) to achieve the noise-like pulse (NLP) mode-locking operation in the erbium (Er)-doped fiber laser (EDFL) at 1552 nm and ytterbium (Yb)-doped fiber laser (YDFL) at 1038.5 nm. Additionally, by shortening the cavity length of EDFL and finely optimizing the intracavity polarization, various solitons, and dual-wavelength solitons were also observed. Moreover, the dynamic evolution of spectra and pulses in YDFL was simulated using scalar nonlinear Ginzburg-Laudau equation (GLE). Our work well demonstrated the broadband and high-efficiency saturable absorption in CuO nanorods, paving the path for investigating multi-soliton dynamics and broadband ultrafast photonics.

Passively mode-locked fiber lasers with broadband FeOOH saturable absorber

In this contribution, we synthesized iron oxide hydroxide (FeOOH) nanomaterials and successfully demonstrated the application of FeOOH-based saturable absorbers in ultrafast photonics at 1 μm and 1.5 μm. Various characterizations were conducted to analyze the morphological and structural features of FeOOH nanomaterials. Subsequently, a tapered fiber coated with FeOOH was integrated into the resonator as a saturable absorber, exhibiting the significant saturable absorption effect with modulation depths of 1.26 % at 1 μm and 2.61 % at 1.5 μm, respectively. In an Yb-doped fiber laser, stable noise-like mode-locking pulses were achieved with a pulse duration of 519 fs at the operating wavelength of 1037.2 nm with a full-width at half-maximum (FWHM) spectral bandwidth of 4.7 nm, yielding a maximum single pulse energy of 1.23 nJ with a high signal-to-noise ratio (SNR) of 47.8 dB. Meanwhile, the conventional soliton pulses were produced in the passively mode-locked Er-doped fiber laser, featuring a pulse duration of 1.02 ps, and an SNR of 42.5 dB at a peak wavelength of 1559.25 nm with a FWHM bandwidth of 2.8 nm. This work demonstrates the considerable nonlinear optical properties of FeOOH nanomaterials in the near-infrared range, proposing a promising saturable absorber for ultrafast photonics applications.

Wavelength-tunable quasi-unidirectional spatiotemporal mode-locked solitons in an isolator-free Er-doped fiber laser

In this letter, we have demonstrated the realization of the wavelength-tunable spatiotemporal mode-locked (STML) operation in an Er-doped partial multimode fiber laser without the intracavity isolator. The laser adopts an all-fiber structure and the saturable absorption effect is attributed to nonlinear multimode interference (NL-MMI) from the single mode fiber-graded index multimode fiber-single mode fiber (SMF-GIMF-SMF) design. The STML laser can operate in the quasi-unidirectional regime with an emission strength difference of larger than 30 dB for the two counter-propagating lasers. And the switching between the dominating operating directions in the clockwise (CW) or counter-clockwise (CCW) directions can be easily achieved by adjusting the MM polarization controller (PC). Both STML conventional solitons (CSs) and the STML soliton molecules are obtained with a similar tunable wavelength from ∼1.56 μm to ∼1.58 μm for the opposite operating directions. Furthermore, the spatial dynamics of the STML soliton are also investigated in detail. The experimental results are of great help for us to explore nonlinear spatiotemporal dynamics and provide potential applications in fields of all-optical signal processing, fiber sensing and information coding.

Passively Q-Switched Er-Doped Fiber Laser Based on Bentonite Clay (Al2H2O6Si) Saturable Absorber.

This paper presents the investigations toward the direct use of bentonite clay (Al2H2O6Si) nanoparticles to act like a saturable absorber (SA) for the Q-switched pulse operation of an erbium-doped fiber laser (EDFL). The measured results reveal that with the incorporation of bentonite clay nanopowder as a SA, an EDFL is realized with a Q-switching mechanism starting at a pump power of 30.8 mW, and a Q-switched emission wavelength was noticed at 1562.94 nm at 142 mW pump power. With an increased pump from 30.8 mW to 278.96 mW, the temporal pulse parameters including minimum pulse duration and maximum pulse repetition rates were reported as 2.6 µs and 103.6 kHz, respectively. The highest peak power, signal-to-noise ratio, output power and pulse energy were noticed to be 16.56 mW, 51 dB, 4.6 mW, and 47 nJ, respectively, at a highest pump power of 278.96 mW. This study highlights the significance of bentonite clay (Al2H2O6Si) nanoparticles as a potential candidate for a saturable absorber for achieving nonlinear photonics applications.

Passively mode-locked Er-doped fiber laser with single and double wavelength pulses based on germanene saturable absorber

In this paper, we focus on the single crystal material germanium (Ge), which is fabricated into saturable absorbers (SAs) employing liquid phase exfoliation, and validate it with an erbium-doped fiber laser (EDFL). The Ge SA was obtained with a modulation depth of 9.8% and a saturation intensity of 11.02 MW cm−2. The single-wavelength mode-locked pulse with a minimum pulse width of 847 fs was obtained at a cavity length of 10.5 m. In addition, at a cavity length of 106 m, a dual-wavelength mode-locked phenomenon was obtained in which the central wavelengths were located at 1559.20 nm and 1561.31 nm. The experimental results show that Ge nanosheets in an EDFL provide a strong basis for the development of nonlinear optics and have a wide range of applications in the field of pulsed fiber lasers.

Generation of vector soliton mode-locked Er-doped fiber laser using ZrTe2 as saturable absorber

We demonstrate a passively mode-locked fiber laser employing zirconium telluride (ZrTe2) as saturable absorber and illustrate its application for vector soliton generation in erbium-doped fiber lasers. By tuning the pump power and polarization controller, stable mode-locked operations in different operations are obtained with different cavity lengths. In addition, we also further research on characteristics of the vector solitons formed in fiber laser. The vector features of the obtained solitons are experimentally explored, and these solitons are proved to be group velocity locked vector solitons. Our research results indicate that ZrTe2 nanosheets could be available saturable absorber for ultrashort pulse fiber lasers, especially for generating vector soliton pulses in fiber lasers.

Organic frame metal structure materials UIO-66 for picosecond ultrafast pulsed fiber lasers

The UIO-66 studied in this paper exhibits unprecedented thermal stability with a very high surface area and mechanical strength. This unique combination of properties opens up a wide range of promising applications. Here, we investigate the saturable absorption effects and ultrafast photonic applications of UIO-66. It shows that UIO-66 could emerge as a novel nonlinear material for ultrafast optics. By fabricating a real saturable absorber and incorporating it into a passively mode-locked Er-doped fiber laser, traditional solitons with a pulse duration of 0.96 ps at a repetition rate of 4.12 MHz have been obtained. The mode-locked spectrum centered at 1562.4 nm features a full width at half maximum of 3.5 nm. Our results may trigger follow-up investigations on the optical properties of UIO-66 and pave potential avenues for photonic and optoelectronic applications.

Copper phthalocyanines as a mode-locker in an Er-doped fiber laser.

We demonstrate a mode-locked erbium-doped fiber laser (EDFL) utilizing copper phthalocyanines (CuPc) as a saturable absorber (SA) for the first time, to the best of our knowledge. The investigated SA was prepared using a simple, low-cost and straightforward technique, whereby the CuPc powder was embedded into polyvinyl alcohol (PVA) to form a thin film. The thin film acted as a mode-locker when it was incorporated into the EDFL cavity to produce output pulses at a repetition rate of 1.8MHz with a pulse duration of 1.98ps. The frequency spectrum showed a signal-to-noise ratio as high as 55dB, which indicates the stability of the mode-locking operation. To the best of our knowledge, this is the first work to report using CuPc as a mode-locker.

Transient breathing dynamics during extinction of dissipative solitons in mode-locked fiber lasers

The utilization of the dispersive Fourier transformation approach has enabled comprehensive observation of the birth process of dissipative solitons in fiber lasers. However, there is still a dearth of deep understanding regarding the extinction process of dissipative solitons. In this study, we have utilized a combination of experimental and numerical techniques to thoroughly examine the breathing dynamics of dissipative solitons during the extinction process in an Er-doped mode-locked fiber laser. The results demonstrate that the transient breathing dynamics have a substantial impact on the extinction stage of both steady-state and breathing-state dissipative solitons. The duration of transient breathing exhibits a high degree of sensitivity to variations in pump power. Numerical simulations are utilized to produce analogous breathing dynamics within the framework of a model that integrates equations characterizing the population inversion in a mode-locked laser. These results corroborate the role of Q-switching instability in the onset of breathing oscillations. Furthermore, these findings offer new possibilities for the advancement of various operational frameworks for ultrafast lasers.Graphical abstract

Q-switched Er-doped fiber laser using an aqueous solution of gold nanorods and polyvinyl alcohol

Authors reported the generation of Q - Switched pulses in an erbium-ytterbium co-doped fiber laser using an aqueous solution of colloidal gold nanorods (GNRs) and Polyvinyl Alcohol (PVA) as a saturable absorber (SA). The effect of the GNRs and PVA concentrations on the pulses has been explored. Passive Q-Switching is achieved at 1.1 W (1.8 A). Pulses with a minimum width of 9.6 µs having a repetition rate of 21.5 kHz and a maximum energy of 0.15 µJ at 1.56 μm are obtained for a pump current of 2.195 W (3.12 A).