Erbium-doped Fiber Laser Research Articles

Unleashing the nonlinear optical response of layered vanadium diselenide towards the deep mid-infrared regime

Broadband nonlinear optical materials towards the deep mid-infrared regime are highly required in medical diagnostics, environmental pollution monitoring, etc. Here, we report the ultra-broadband nonlinear optical absorption behavior of the layered vanadium diselenide (VSe2) towards deep mid-infrared regime experimentally. The layered VSe2 prepared by the liquid-phase exfoliation method exhibits broadband and wavelength-dependent nonlinear saturable absorption and a large modulation depth of over 8% in the 3-10 µm spectral range. By utilizing the layered VSe2 for optical modulation, stable nanosecond pulse with a low Q-switched threshold has been delivered successfully from an erbium-doped ZBLAN fiber laser. The experimental findings can deepen the understanding of the nonlinear optical response of the transition metal dichalcogenides towards the deep mid-infrared regime, and may make inroads for the advancement of mid-IR optoelectronic devices.

Generation of dark pulses in mode-locked erbium-doped fiber ring laser using Ti2SnC absorber

Abstract We report the experimental observation of domain-wall type dark solitons in an all-fiber ring cavity erbium-doped fiber laser (EDFL) mode-locked with a Titanium Tin Carbide (Ti2SnC) saturable absorber (SA). The SA, featuring a modulation depth of 8.2%, was created by incorporating Ti2SnC particles into a polyvinyl film. Dark pulse formation is attributed to cross-phase coupling resulting from cavity birefringence. The mode-locked laser operates at 1559 nm with pump power ranging from 30.9 mW to 90.0 mW, achieving a maximum pulse energy of 1.73 nJ, a repetition rate of 1.78 MHz, and a pulse width of 261.2 ns.

A Tunable and Switchable Multi-Wavelength Erbium-Doped Fiber Ring Laser Enabled by Adjusting the Spectral Fringe Visibility of a Mach-Zehnder Fiber Interferometer

This paper presents a tunable, switchable multi-wavelength emission from an erbium-doped fiber ring laser, enabled by adjusting the spectral fringe visibility of a fiber interferometer filter. The filter is formed with specially designed concatenated tapered fibers to configure a Mach-Zehnder fiber interferometer (MZFI). The laser emission is highly flexible and reconfigurable, allowing for tuning between single- and dual-wavelength operation. The laser can switch sequentially from one up to six wavelengths by fixing the curvature and adjusting the polarization state. The lasing emission is generated over a stable wavelength range between 1559.59 nm and 1563.54 nm, exhibiting an optical signal-to-noise ratio (OSNR) exceeding ~35 dB. The performance of amplitude and wavelength fluctuations were evaluated, indicating an appropriate stability of ~3 dB and a shift less than 0.1 nm within a 45 min period at room temperature. A detailed comparison with the literature is given.

Passively Mode-Locked Erbium-Doped Fiber Laser and Application in Laser Thrombolysis

Fiber lasers have been widely used in surgery with the development of fiber photonics. Since the human body is prone to myocardial infarction caused by blood clots, laser thrombolysis was proposed as a safe and efficient treatment. Mode-locked fiber lasers have high peak power and narrow pulse width. In order to observe the effect of laser thrombolysis with mode-locked fiber lasers, a 1.5 µm mode-locked fiber laser based on carbon nanotubes was built, showing a pulse width of 1.46 ps, a 3 dB bandwidth of 1.65 nm, and a repetition rate of 29.5 MHz. The output pulses were amplified by an erbium-doped fiber amplifier to the hundred-milliwatt level and were applied to the surface of a self-made thrombus. The influences of lasing power and time on the damage diameter of the thrombus surface were evaluated. A low threshold damage power of 45 mW was observed, which resulted from the high peak power of the mode-locked pulses. These results demonstrate that high ablation efficiency can be achieved by using mode-locked pulses with a narrow pulse width and high peak power.

Mode-locked soliton pulse generation using copper phthalocyanine absorber in long erbium-doped fibre laser cavity

We present the development of a mode-locked erbium-doped fibre laser (EDFL) utilizing Copper Phthalocyanine (CuPc) as a saturable absorber (SA). CuPc exhibits unique optical properties, including its high nonlinear optical response and rapid recovery time. To seamlessly integrate CuPc into the laser cavity, we employed a simple embedding technique within a polymer film. The SA demonstrates a modulation depth of 3.1% and a saturation intensity of 17 MW/cm2. Operating within a pump power range of 90.6 to 122.9 mW, the laser achieves mode-locked operation, producing a soliton pulse train with a fundamental frequency of 1.82 MHz and a pulse width of 6.4 ps at a wavelength of 1561.5 nm. It attains a maximum output power of 13.97 mW and a pulse energy of 7.67 nJ. These results underscore CuPc's potential as a promising material for generating mode-locked pulses, suggesting new avenues in ultrafast laser development for diverse applications.

On the Synthesis of Graphene Oxide/Titanium Dioxide (GO/TiO2) Nanorods and Their Application as Saturable Absorbers for Passive Q-Switched Fiber Lasers.

We report passively Q-switched pulse operation through an erbium-doped fiber laser (EDFL) utilizing graphene oxide/titania (GO/TiO2) nanorods as a saturable absorber. The GO/TiO2 nanorods were fabricated using a Sol-gel-assisted hydrothermal method. The optical and physical characterization of the GO/TiO2 was then characterized using a field-emission-scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDS), and diffuses reflectance spectroscopy (DRS). To investigate the performance of the Q-switched EDFL based on the GO/TiO2 SA, the prepared nanorods were mechanically deposited on the fiber ferrule employing adhesion effects of in-dex-matching gel. This integration of the nanorod SA resulted in a self-starting Q-switching opera-tion initiated at a pump power of 17.5 mW and sustained up to 306.9 mW. When the pump range was tuned from 17.5 to 306.9 mW, the emission wavelength varied from 1564.2 to 1562.9 nm, pulse repetition rates increased from 13.87 kHz to 83.33 kHz, and pulse width decreased from 30.27 µs to 3.75 µs. Moreover, at the maximum pump power of 306.9 mW, the laser exhibited an average output power of 0.74 mW, a peak power of 1.54 mW, and a pulse energy of 8.88 nJ. Furthermore, this study investigates the GO/TiO2 damage threshold and prolonged stability of the proposed EDFL system.

Erbium-Doped Tunable Fiber Laser Based on a Vernier Effect Filter

A novel vernier effect filter is designed utilizing two cascaded Mach–Zehnder interferometers (MZIs). Integrating the filter into an erbium-doped fiber laser (EDFL), the tunability of laser wavelength is achieved. Each MZI comprises two sequentially interconnected 3 dB optical couplers (OCs), where the incoming light is initially split into two arms at the first OC and subsequently recombined at the second OC. Interference occurs due to the optical path difference between these two beams. Notably, the two MZIs exhibit closely matched free spectral ranges (FSRs), leading to the formation of a broadened envelope in the superimposed spectrum. By delicately adjusting the optical path difference between the two arms of one MZI, a little drift of the interference spectrum is induced. This small amount of drift, in turn, triggers a significant movement of the envelope, giving rise to the so-called vernier effect. Integrating the vernier effect filter into an EDFL, the wavelength of the fiber laser can be tuned from 1542.56 nm to 1556.62 nm, with a tuning range of 14.06 nm. Furthermore, by employing a high-precision stepper motor, a remarkable tuning accuracy of 0.01 nm is attainable. The side mode suppression ratio of all wavelengths is above 55 dB. In comparison to reported tunable fiber lasers utilizing MZI filters, the proposed fiber laser in this study offers enhanced precision and a more user-friendly tuning process.

1.6 µm tunable and switchable single-frequency erbium-doped fiber laser

We present a tunable and switchable single-frequency (SF) erbium-doped fiber laser (EDFL) operating at 1.6 µm. For the first time, a multichannel Sagnac filter, a “θ” sub cavity, and a saturable absorber (SA) have been combined to achieve SF operation of single- and dual-wavelength tunability as well as single-dual-triple-wavelength switching. The laser exhibited excellent stability, with no mode-hopping over the 60-minute observation period. Furthermore, linewidths measured utilizing the short-delay self-heterodyne interferometry method are less than 300 Hz. The investigated narrow linewidth SF EDFL has the potential to extend the applications in optical communications and provide a new idea for L-band tunable lasers.

Experimental State Observer of the Population Inversion of a Multistable Erbium-Doped Fiber Laser

Experimental State Observer of the Population Inversion of a Multistable Erbium-Doped Fiber Laser

Passively mode-locking fiber laser based on Cr2Si2Te6 saturable absorber

This paper reports on the generation of third-order harmonic mode-locking, double-pulse phenomena, and conventional solitons in an erbium-doped fiber laser using Cr2Si2Te6 as a saturable absorber (SA). The double-balance probing method was employed to examine the nonlinear characteristics of Cr2Si2Te6-SA. Its modulation depth is 2.35 %, and its saturation intensity is 29.74 MW/cm2. We discovered conventional soliton functioning with a center wavelength of 1561.8 nm at a pump power of 34.76 mW. It has a repetition frequency of 6.76 MHz and a signal-to-noise ratio of 45 dB. As the pump power increased, the traditional soliton was able to maintain its existence in the range of 34.76 mW to 80.96 mW. The maximum output power reaches 1.1 mW when the pump power is 80.96 mW, and the maximum single-pulse energy of the conventional soliton is 0.16 nJ. Furthermore, we observed third-order harmonic mode-locking and double-pulse phenomena at pump outputs of 53.65 mW and 71.16 mW. The experimental findings demonstrate the excellent nonlinear effect of the SA based on Cr2Si2Te6. In ultrashort-pulse fiber lasers, Cr2Si2Te6 nanosheets can be employed as an efficient saturable absorption material.

Correlation between soliton state and power in erbium-doped fiber lasers based on PtS2 saturable absorbers

Over the past few years, there has been a significant amount of interest in transition metal dichalcogenides (TMDs) materials within the fiber laser area. PtS2 as a typical TMD family material, has a tunable and narrow bandgap, and the material is stable and easy to exfoliate. This material is an excellent option for a saturable absorber (SA) in fiber lasers. In this work, PtS2-SA was obtained by liquid phase exfoliation (LPE) and using tapered fibers. A multi-soliton erbium-doped fiber laser based on PtS2-SA is realized. Experiments were performed by improving the pump power to sequentially realize three soliton phenomena. They were conventional soliton (CS), 120th order harmonic mode-locking (HML) and dissipative soliton resonance (DSR). This work demonstrates that PtS2 has good saturable absorption properties. The potential of PtS2 in the field of fiber lasers is demonstrated. It is valuable for the study of soliton evolution.

All-polarization-maintaining Figure-9 Erbium-doped modelocked fiber laser based on bidirectionally pumped weak asymmetric NALM

All-polarization-maintaining Figure-9 Erbium-doped modelocked fiber laser based on bidirectionally pumped weak asymmetric NALM

Stable and Tunable Erbium Ring Laser by Rayleigh Backscattering Feedback and Saturable Absorber for Single-Mode Operation

This work demonstrates a high-quality erbium-doped fiber (EDF) ring laser in the L-band gain range by combining the Rayleigh backscattering (RB) feedback signal and unpumped EDF induced saturable absorber (SA) filter. The optical filter effect induced by the RB feedback injection and EDF SA could generate single-longitudinal-mode (SLM) behavior and shrink the linewidth to sub-kHz. The output linewidth, power, and optical-signal-to-noise ratio (OSNR) of the fiber ring laser were also shown within the 42 nm wavelength bandwidth of 1565.0 to 1607.0 nm. Also, the instabilities of output power and central wavelength of each lasing lightwave were analyzed with a measurement time of 45 min.

Tunable Narrow Linewidth Erbium-Doped Fiber Ring Laser Based on Saturable Absorber and Self-Injection Feedback

Tunable Narrow Linewidth Erbium-Doped Fiber Ring Laser Based on Saturable Absorber and Self-Injection Feedback

Study of step-like pulses from a mode-locked erbium-doped fiber laser in L-band

This paper presents a numerical simulation and an experiment on the generation of step-like pulse in an ultra-long cavity passively mode-locked erbium-doped fiber laser based on nonlinear optical loop mirror (NOLM). The gain competition phenomenon and the peak power clamping (PPC) effect of the step-like pulse are investigated with reasonable transmittance equation. To the best of our knowledge, this paper is the first interpretation and simulation of step-like pulse. And we believe that the findings contribute to the enrichment of nonlinear dynamics understanding and are anticipated to enhance laser performance optimization.

Self – assembled aligned single – walled carbon nanotubes as an anisotropic polarizer and saturable absorber in erbium-doped femtosecond fiber laser

We report the production of a saturable absorber (SA) based on aligned single-walled carbon nanotubes SWCNTs by the self-assembly method. The ultrafast saturation behavior of prepared aligned and random nanostructures shows an increase of modulation depth by 6% due to the alignment method. We also observed the dependence of aligned SWCNTs loss on the polarization direction of laser radiation. All-fiber Er-doped hybrid mode-locked fiber laser was demonstrated based on the aligned /random SWCNTs-based SAs. We achieved the generation of stable stretched pulses with a pulse duration of 490/569 fs and an average output power of 20.7/18.25 mW. We also investigated the advantages of using aligned SWCNTs compared to the typical structure with random tube distribution. We show that the use of aligned SWCNTs film increased the SNR by 24.5, decreased the mode-locking threshold power by 42 mW, and decreased the RIN level by (20-25) dB in the frequency range [∼ 0 Hz- 100 kHz] and ∼ 8 dB in the range [100 kHz – 1 MHz].

Nanostructured LNTO saturable absorber for generating multi-wavelength laser in Q-switched EDFL

In this paper, we propose a new and efficient ferroelectric nanostructure metal oxide lithium niobate [(Li1.075Nb0.625Ti0.45O3), (LNTO)] solid film as a saturable absorber (SA) for modulating passive Q-switched erbium-doped fiber laser (EDFL). The SA is fabricated as a nanocomposite solid film by the drop-casting process in which the LNTO is planted within polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] as host copolymer. The optical and physical characteristics of the solid film are experimentally established. The SA is incorporated within the cavity of EDFL to examine its capability for producing multi-wavelength laser. The experimental results proved that a multi-wavelength laser is produced, where stable four lines with central wavelengths at 1529.5, 1530.5, 1531.5, and 1532 nm are observed on the laser spectrum at 157 mW pumped power. Furthermore, at maximum available pumped power (157 mW), laser pulses are running with a rate of 178 kHz and pulse width of 2.64 μs. The output power of 3.7 mW is attained at pumped power of 157 mW. The result proved that the LNTO-SA could be a potential candidate for generating multi-wavelength passive Q-switched fiber laser pulses.

Dynamics of coupled erbium-doped fiber lasers: Modulation effects and synchronization patterns

Studying the dynamics of coupled Erbium-Doped Fiber Lasers helps in optimizing the performance of these systems in different applications. An important factor in these systems is the modulation signal which can affect the dynamics of systems, leading to complex behaviors including diverse periodic and chaotic dynamics. This paper investigates the dynamics of a ring network of Erbium-Doped Fiber Lasers and compares its behaviors in the presence and absence of the modulation. The results reveal that although complete synchronization is not reachable, certain synchronization patterns exist during the periodic oscillations. In the non-modulated network, two distinct clusters are formed which can achieve lag synchronization under specific coupling intensities. While in the coupled modulated systems, the chimera state may form. These findings represent the complex relationship among modulation, coupling intensity, and network dynamics in EDFL systems.

Eight-wavelength-switchable single-frequency fiber laser with scattering-enhanced fiber-based wavelength self-adaptive linewidth compression

We demonstrate an eight-wavelength-switchable single-frequency (SF) ultra-narrow linewidth erbium-doped fiber laser (EDFL). A switchable polarization-dependent eight-channel filter (S-PDECF), fabricated using femtosecond laser direct-writing technology, determines the eight wavelengths of the laser output, with four channels concentrated near 1530 nm and the other four near 1550 nm. A dual-coupler ring-based compound-cavity filter is utilized to achieve single-longitudinal-mode selection for the EDFL. The introduction of a femtosecond laser direct-written scattering-enhanced fiber (SEF) effectively narrows the laser linewidth, enabling ultra-narrow linewidth outputs lasing at all eight wavelengths, and the wavelength self-adaptive linewidth compression of the SEF is verified for the first time. Furthermore, the incorporation of SEF significantly enhances the overall performance of the EDFL. The eight switchable single-wavelength laser outputs all exhibit exceptional characteristics, including spectral wavelength fluctuations of ≤0.011 nm, spectral peak power fluctuations of ≤0.54 dB, optical signal-to-noise ratios of ≥71 dB, linewidths of ≤248 Hz, output power fluctuations of ≤0.252 dB over a 10-min measurement period, and relative intensity noise of ≤−150.17 dB/Hz @≥ 3 MHz.

Q-switched Erbium-doped Fiber Laser Utilising a Saturable Absorber Based on Brass Nanoparticles

A passively Q-switched erbium-doped fiber laser was successfully demonstrated using brass nanoparticles embedded in Polyvinyl alcohol film as a saturable absorber. The brass nanoparticles were produced by ablating brass target in polyvinyl alcohol solution using Nd:YAG laser. The saturable absorber was characterised in terms of its morphology, elemental contents and optical properties. It was incorporated into a ring cavity to function as a Q-switcher for generating pulses. As the pump power was varied from 21 mW to 67 mW, the repetition rate increased from 38.74 kHz to 73.75 kHz while the corresponding output pulse width and pulse energy varied from 5.11 μs to 2.473 μs and 69.6 nJ to 145.6 nJ respectively. The output power characterised by the slope efficiency of 17.72 % and 10.74 mW of output power recorded at 67 mW pump power.