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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - All-Polarization-Maintaining Dual-Color/Dual-Comb Yb:Fiber Laser
摘要： Dual-comb spectroscopy systems based on two pulse trains emitted from a single laser cavity benefit from passive mutual coherence between the two pulse trains, which leads to common-mode noise cancellation in the down converted radio-frequency (RF)-comb [1]. Due to their robustness, single cavity dual-color/dual-comb fiber lasers are promising candidates for such spectroscopy systems [2,3]. Here, we present a novel method to generate two pulse trains out of a single fiber laser cavity based on mechanical spectral filtering, which offers two key features: dynamical adjustment of the spectral separation between the two pulse trains and tuning of the difference in repetition rates. After demonstrating the concept in a 23-MHz nonlinear polarization evolution (NPE) mode-locked ytterbium (Yb) laser [4], we have now for the first time implemented this concept in a nonlinear amplified loop mirror (NALM) mode-locked all-polarization maintaining (PM) Yb:fiber laser operating at a repetition rate of 77 MHz, thus improving both the stability as well as the non-aliasing dual-comb bandwidth. The laser contains a free-space arm with a transmission grating compressor, in which the spectral components of the intra-cavity light are spatially dispersed (Fig.1(a)). By introducing a small beam block into the grating compressor, we split the spectrum into two separate regions. We show that these two spectral regions can be independently mode-locked, thus creating two pulse trains with slightly different repetition rates (Fig.1(b-d)). Due to the spatial distribution of the spectral components, we can vary the width of the spectral cut between the two spectra by rotating the beam block (Fig. 1(b), blue curves). Furthermore, adjusting the grating spacing (and thus the amount of dispersion) allows us to tune the difference in the repetition rate ?frep from 1-6 kHz (Fig. 1(e)). After spectral separation at the cavity output, the pulse centered around 1030 nm is amplified and broadened in a nonlinear fiber to create a spectral overlap with the 1060 nm-pulse (Fig. 1(f)). The overlapping spectrum is bandpass-filtered around 1055 nm and sent onto a photodiode (PD). An oscilloscope trace of the PD output shows interferograms (Fig. 1(f), inset) occurring with a periodicity of 1/?frep, which correspond to the Fourier-transform of the down-converted RF comb that is generated by the beating of both optical combs.
关键词： repetition rate tuning,polarization maintaining,Yb:fiber laser,spectral filtering,Dual-comb spectroscopy
更新于2025-09-11 14:15:04
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A theoretical investigation of erbium‐doped fiber laser as a function of ion‐clustering, temperature, pumping wavelength, and configuration
摘要： The lasing performance of an erbium-doped fiber laser (EDFL) is affected by several factors such as doping concentrations, erbium-ion clustering, pumping wavelength, pumping configuration, and temperature. In this article, the performance of an EDFL has been investigated as a function of erbium-ion clustering, pumping wavelength, pumping configuration, and temperature. In our investigation, we have found that power degradation, which happens due to ion-clustering, at around 1530 nm is less affected for 980 nm pumping than for 1480 nm pumping. Moreover, a wider tuning range is achieved for 980 nm pumping than 1480 nm pumping. Our simulation results also show that the forward pumping configuration is suitable for a wider tuning range. To our best knowledge, pumping wavelength and configuration effects on an EDFL performance have not been investigated yet. We have also investigated the temperature effects on an EDFL performance and found little influence on lasing performance, at least within 30°C to 80°C.
关键词： doping concentration,pumping wavelength,temperature,pumping configuration,erbium-ion clustering,erbium-doped fiber laser (EDFL)
更新于2025-09-11 14:15:04
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Experimental investigation and modeling of heat affected zone and surface roughness in erbium-doped fiber laser cutting of CFRP composite
摘要： In the current era, two types of the composite, namely polymer-based composites and metal matrix composite materials are used in the industrial application, and the demand for an increase in its production is rapidly growing. But these composite materials are not so widely acceptable in the industries due to its non-machinability nature by conventional methods. Various reasons like the incorporation of defects, high strength, and hardness of the composite make the production of intricate shapes not easily achievable by traditional methods which lead to the development of new non-conventional machining methods. Laser machining method is one of the non-conventional methods which are becoming popular for cutting of composite materials due to its advantages of fast cutting speed and no contact with the workpiece. In this experimental work, an erbium-doped fiber laser is used to study the machinability of carbon fiber reinforced polymer composite and effect of various machining parameters are observed on the performance responses like heat affected zone and surface roughness. It was found that composite was easily machinable with some surface defects which were detected by SEM images. The decrease in power with an increase in scan speed and standoff distance reduces surface roughness and heat affected zone in the material.
关键词： Fiber Laser,CFRP composite,HAZ,RSM,Surface roughness
更新于2025-09-11 14:15:04
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Near-Infrared Soliton Mode-Locked Thulium Doped Fibre Laser Using WS <sub/>2</sub> -ZnO Composite Material as Saturable Absorber
摘要： The generation of a highly stable passive mode locking laser is realized in a thulium doped ?bre laser using a WS2-ZnO composite as a saturable absorber. Soliton mode locking pulses are generated with a central wavelength of 1936 nm and full-width half maximum (FWHM) of 3.06 nm. The ?rst order Kelly’s side band is located at around 5.65 nm from the central wavelength which gives the calculated pulse width value of 1.26 ps. This value corresponds well with the measured pulse width of 1.27 ps using the autocorrelator. The output power of the laser is around 0.44 mW with the peak power of 29.7 W and repetition rate of 9.96 MHz. This laser set-up is highly robust and realizes highly stable laser pulses in the mid-IR wavelength range for a multitude of applications.
关键词： Fiber Laser,2 micron,Thulium
更新于2025-09-11 14:15:04
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Soliton Molecules in Self-Mode-Locked Ring-Cavity Er/Yb Double-Clad Fiber Laser
摘要： In this paper, generation of soliton molecules by a self-mode-locked Er/Yb double clad fiber laser is experimentally demonstrated. The optical spectrum of the bound solitons exhibits eight well defined peaks at ~1563 nm with high modulation depth. The corresponding autocorrelation measurement shows a fundamental trace with several narrow peaks, suggesting the presence of bound solitons. The obtained results demonstrate the reliability of our simple laser configuration for the formation of more robust soliton molecules as the pump power is increased. The soliton molecules exhibit repetition rate of 19.54 MHz and average power of 1.2 W, achieved with a pump power of ~4.8 W.
关键词： mode-locked lasers,Fiber laser,pulse propagation and temporal solitons
更新于2025-09-11 14:15:04
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112-μJ 180-fs pulses at 1-kHz repetition rate from Yb-doped laser based on strictly all-fiber CPA structure
摘要： In this paper, we reported an Yb-doped, femtosecond, chirped pulse amplification laser based on strictly all-fiber structure. It operated at a low repetition rate of 1 kHz and adopted the synchronously pumping technology to suppress ASE and heat accumulation. A chirped fiber Bragg grating providing adjustable dispersion is used as the pulse stretcher. High order dispersion induced by fiber, grating pair in the system was compensated accurately. Laser pulse with duration of 180 fs and energy of 112 μJ has been obtained. In addition, it has a high long-term stability of energy and a good beam quality, corresponding to energy fluctuation of 0.62% in an hour and M2 factor of 1.15, respectively.
关键词： femtosecond fiber laser,high energy,Chirped pulse amplification,synchronously pumping technology
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Computational High-Resolution Dual-Comb Spectroscopy with a Free-Running All-Fiber Laser
摘要： Dual-comb spectroscopy (DCS) has experienced a remarkable growth propelled by recent advances in fiber and semiconductor technology. A key enabler for DCS is mutual stability between two repetition-rate-mismatched frequency combs, which conventionally relies on feedback loops employing additional optics and electronics to synchronize a pair of sources. This limitation can be overcome in several ways, of which one of the most promising is the generation of two frequency combs in a single free-running fiber laser cavity [1–3]. To date, however, the only configuration proven to be compatible with Doppler-limited spectroscopy was the dual-color laser presented in Ref. [2] requiring external spectral broadening, thus adding an extra layer of complexity. Here, we report on the realization of a drastically simplified all-fiber dual-comb laser (AFDCL) with an unprecedentedly low number of components and battery-operation-compatible electrical power consumption (0.35 W) with excellent suitability for spectroscopy of Doppler-limited transitions (Fig. 1). A key feature of our solution relying on polarization-multiplexing [3] is that the laser cavity has an easily adjustable repetition rate difference ranging from sub-kHz to dozens of kHz obtained by varying the intracavity polarization state using polarization controllers (PC) and/or the length of the polarization maintaining fiber in the cavity, which is not possible in the dual-color or bidirectional schemes. Furthermore, we achieve uninterrupted operation times of dozens of hours, and a record-high repetition rate for an AFDCL exceeding 140 MHz to maximize the optical power per comb tooth. High-resolution molecular dual-comb spectroscopy in free-running mode is made possible thanks to a novel real-time compatible phase correction algorithm that marks a radical departure from the cross-correlation or cross-ambiguity function paradigm, hence considerably lowering the complexity of such procedures. As a demonstration, we measure P18-P27 lines of the 2ν3 band of H13C14N at 10 Torr with FWHM Doppler line widths of ~450 MHz within 200 ms (Fig. 1b,c) with better than 1% of precision in a 1 THz bandwidth.
关键词： high-resolution,free-running,molecular spectroscopy,Dual-comb spectroscopy,all-fiber laser
更新于2025-09-11 14:15:04
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Single- and dual-wavelength switchable mode-locked dissipative soliton Yb-doped fiber laser based on graphene/WS <sub/>2</sub> nanocomposites modelocker and polarization controller
摘要： We report a single- and dual-wavelength switchable mode-locked dissipative soliton in an ytterbium-doped fiber laser based on graphene/WS2 nanocomposites saturable absorber. The graphene/WS2 nanocomposites film possesses efficient saturable absorption characteristics with large modulation depth (45.1%), which results in the stable single-wavelength mode-locking operation with pulse duration of 450 ps. By carefully rotating the polarization controller, the mode-locking operation can be switched to a dual-wavelength at both 1066.4 nm and 1069.2 nm due to the modulation of the intracavity birefringence. Our work extends the studies for 2D nanomaterials and supplies potential applications in the multi-wavelength fiber laser.
关键词： mode-locked fiber laser,saturable absorber,dual-wavelength,graphene/WS2 nanocomposites,dissipative soliton
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Multiple Switchable Generation between Noise-Like Pulse and Dissipative Soliton in an Er-Doped Fiber Laser Based on Nonlinear Polarization Rotation
摘要： In addition to some regular pulses such as conventional soliton (CS) and dissipative soliton (DS), passively mode-locked fiber lasers can also generate another type of distinctive pulse, i.e. the so-called noise-like pulse (NLP) [1]. Generally speaking, in NLP fiber lasers, NLP can be switched from CS or DS by increasing the pump power or adjusting the polarization controller (PC) [2]. However, as far as we know, multiple switchable generation between NLP and DS or CS have never been reported. We here show the multiple switchable phenomenon between NLP and DS from an Er-doped fiber laser (EDFL) based on nonlinear polarization rotation (NPR) for the first time. This kind of fiber laser not only facilitates the deep understanding of the properties and mechanisms of NLP but also paves a new way for the design of multi-functional light source.
关键词： noise-like pulse,dissipative soliton,nonlinear polarization rotation,Er-doped fiber laser,multiple switchable generation
更新于2025-09-11 14:15:04
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Comparison of Different Mode-Locking Methods in the Ho-Doped Fiber Laser
摘要： Ultrafast fiber sources operating in the spectral range of 2-3 μm have attracted attention due to a number of possible applications, e.g. for perspective communications, gas sensing, nonlinear frequency conversion, and medicine. Holmium-doped fibers (HDF) are commonly used as a gain medium for 2 μm lasers due to their broad gain spectrum, extending from 2 to 2.2 μm. Most of the presented works on Ho-doped ultrafast fiber lasers have concentrated on mode-locking regime initiated by saturable absorbers (SAs) such as carbon nanotubes (CNT) [1], graphene [2], black phosphorus [3], and semiconductor saturable absorber mirrors (SESAMs) [4]. The mode-locking regime in an all-fiber Holmium laser also has been obtained by nonlinear polarization evolution (NPE) [5]. In this work, we demonstrate a comparison of different methods of mode-locking obtaining in one Ho-doped fiber laser cavity under the same condition and analyze the parameters of the obtained pulsed radiation. We have compared such methods as NPE and two hybrid regimes: NPE+single walled CNTs [6, 7], NPE+graphene. The optical scheme of the experimental setup is shown in Fig. 1. Ho-doped fiber laser was pumped through a wavelength division multiplexer (WDM) by a custom-made 1125 nm Yb-doped fiber laser delivering up to 8 W of continuous wave power. The cavity of the laser was formed by active Ho-doped fiber (≈ 6 m) and single-mode fiber (≈ 8 m). A fiber polarizer and a pair of polarization controllers were added into the laser cavity to obtain NPE mode-locking. The SWCNTs or graphene SA were fixed between two optical FC/APC-connectors to realize hybrid mode-locking. The isolator (ISO) was used to obtain unidirectional lasing. The pulse signal was coupled out from the laser cavity using a 9/1 fiber coupler (90% coupler output was used as the output of the laser). The total intracavity dispersion was estimated as about –1.5 ps2. Stable pulsed lasing by NPE was obtained at a pump power of 3 W, whereas in the case of NPE+SWCNTs mode-locking lasing threshold increased up to 3.3 W of pump power. The average lasing power in the NPE and NPE+SWCNTs regimes was 6.4 and 4.7 mW, respectively. Fig. 2 shows the emission spectra of a pulsed Ho-doped fiber laser operating in different regimes. As can be seen, the spectra have different values of the central wavelength and full width at half maximum (FWHM). Fig. 3 shows the autocorrelation traces. The pulse width in both cases did not exceed 1.5 ps. The pulse energies in the NPE mode-locking and NPE+SWCNTs mode-locking regimes were 0.4 and 0.3 nJ, respectively. The pulse repetition frequency was 14.9 MHz. The signal-to-noise ratio in the case of NPE+SWCNTs mode-locking was 3 dB better than that implemented under conditions of NPE mode-locking.
关键词： saturable absorbers,mode-locking,hybrid regimes,Ho-doped fiber laser,nonlinear polarization evolution
更新于2025-09-11 14:15:04