- 标题
- 摘要
- 关键词
- 实验方案
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Ultra-Thin Fiber Laser Hydrophone With Static Pressure Equalization and Improved Response
摘要： In this paper, we propose a new scheme that combines a capillary tube with an elastic cavity to develop a thin fiber laser hydrophone (FLH) with static pressure equalization, enhanced dynamic pressure sensitivity and broadband flat response. We demonstrate the improvement on the hydrophone response characteristics by introducing the compensation structure into a diaphragm-based FLH. A hydrophone prototype with a diameter of 7.2 mm was packaged and the hydrophone has a flat pressure sensitivity of 9×10-3 pm/Pa (120 dB re Hz/Pa) over a bandwidth from 40 Hz to 4 kHz. The static pressure sensitivity is ?11×10-6 pm/Pa in the measurement range of 0 to 3 MPa.
关键词： Sonar arrays,optical fiber lasers,hydrophones,optical fiber sensors,pressure equalization
更新于2025-09-11 14:15:04
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Stable multiwavelength Tm‐doped fiber laser with a microfiber knot resonator
摘要： We presented a compact and enduring multiwavelength Tm-doped fiber laser at 2 μm employing a microfiber knot resonator (MKR). The MKR, made by the flame-brushing technique, has a fiber diameter of 10 μm and a ring diameter of 150 μm. The MKR plays a role as both the comb filter and the power equalization device, which is critical for the stable multiwavelength Tm-doped fiber laser. By properly adjusting the pump power, three wavelength lasing channels (1956.2, 1964.4, and 1971.8 nm) were observed stable and their average power density was around ?8.76 dBm with 1 W pump power. In addition, the channel spacing is 5.8 nm with the 3-dB bandwidth of the channel smaller than 0.5 nm. The experiments demonstrated that the MKR can be utilized as a comb filter with the suitable transmission spectrum to reach a steady multiwavelength Tm-doped fiber laser.
关键词： fiber lasers,comb filters,multiwavelength,microfiber knot resonator
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) - Extreme Events Generation via Cascaded Stimulated Brillouin Scattering in Self-Pulsing Fiber Lasers
摘要： Extreme-amplitude events and rare instabilities are observed for more than a decade in various optical systems. Specifically in dissipative systems, such as Raman fiber lasers, laser diodes or mode-locked lasers, to name a few, long-tailed statistics and highly-localized temporal structures have been observed [1,2]. Recent studies showed that stimulated Brillouin scattering (SBS) can also trigger the generation of extreme events in various configurations, from self-pulsing fiber lasers [3,4] to Q-switched random fiber lasers [5]. It is indeed known that the stochastic nature of SBS can promote the emergence of randomly distributed giant pulses which can induce irreversible damages in fiber laser systems. In order to understand and open the possibility to harness such extreme events, numerical models have then to be developed and refined. In the context of self-pulsed fiber lasers, a few studies taking into account only one or two fundamental Stokes orders have already been reported [6]. Such models describe well the large pulse-to-pulse intensity fluctuations observed in Erbium-doped fiber lasers Q-switched through SBS but they however did not predict any extreme event [6]. We propose here an extension of the model proposed in Ref. [3] by generalizing it to higher Stokes orders to study their impact on extreme dynamics in a self-pulsing laser. Our model is based on the coupled amplitudes equations describing the spatiotemporal dynamics of both the laser and Brillouin waves with their corresponding acoustic fields, as well as the temporal variations of the gain for each wave. We also consider a matter equation to account for the saturable absorption effect which can occur in the un-pumped segment of the active fiber. We show that increasing the number of SBS orders interacting with the gain medium reveals new dynamics enabling the generation of extreme events which are not predicted by the single SBS order model. Pulses with amplitudes 27 times the so-called significant wave height are indeed predicted, which attest of the presence of extreme-amplitude events, as shown in Fig. 1. Such giant pulses could then reach the threshold of irreversible damage in optical fibers. We also provide a comprehensive study on the different parameters influencing the dynamics, including the number of Stokes orders that strongly affect the laser dynamical behavior and then allow to somehow control the highest intensity of the laser instabilities. The influence of other parameters, such as the input noise, on the system’s dynamics will be discussed and we will show that our simplified model can pave the way towards a better understanding of the complex stochastic dynamics under the influence of SBS.
关键词： stimulated Brillouin scattering,stochastic dynamics,Extreme events,optical systems,self-pulsing fiber lasers
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) - Optical Soliton Molecular Complexes in Ultrafast Fiber Lasers
摘要： Optical soliton molecules are under intense research focus, owing in particular to the interesting analogies between their self-assembly and internal dynamics, and those of matter molecules. Two interacting dissipative solitons can form a soliton-pair molecule, which can behave as a robust entity traveling around the cavity for an indefinite time [1]. The internal oscillatory dynamics of soliton molecules can be compared to molecular vibrations, though they are fundamentally different [2,3]. The recent experimental investigations in Refs. [2,3] have been enabled by the dispersive Fourier transform (DFT) technique, which allows recording spectral measurements at multi-MHz frame rates. They showed the existence of various oscillatory dynamics among soliton-pair and soliton-triplet basic molecules. Following the analogy between light and matter molecules, we now consider the experimental possibility of forming a “soliton molecular complex” (SMC), namely, a higher-order pattern obtained by the stable bonding of several soliton molecules, and investigating its complex internal dynamics. Such structure implies two different bond types, a strong one within each soliton molecule, and a weaker one to maintain the overall structure. We here report the first real-time recording and analysis of several internal dynamics of SMCs, which support this new structural concept. We shall describe our results concerning the dynamics of the fundamental SMC, made of two soliton-pair molecules, or (2+2)-SMC. The experimental configuration is based on an erbium-doped fiber ring laser, which is mode-locked by means of nonlinear polarization evolution (NPE), and its output spectrum analyzed in real-time through DFT [4]. The formation of various SMC is controlled by the laser output power and the tuning of NPE through the orientation of intracavity waveplates, in an experimental procedure which utilizes the hysteretic laser behavior in the multi-pulse regime. SMCs with sliding-phase and oscillating-phase dynamics have been characterized by real-time spectral interferometry measurements, thus revealing the dynamics of the major internal degrees of freedom of the complexes, namely the dynamics of the relative temporal and phase separations between the different soliton constituents. Numerical simulations confirm the experimental observations and offer an additional insight into the understanding of the complex dynamics of SMCs. By showing that soliton molecules can form various bonds according to the distance between soliton constituents, which we can manipulate, this work opens the way to the manipulation of large-scale optical- soliton complexes, which can be extended to other photonic platforms, such as microresonators.
关键词： soliton molecular complex,Optical soliton molecules,nonlinear polarization evolution,ultrafast fiber lasers,dispersive Fourier transform
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) - High Energy Dissipative Soliton Resonance in a Thulium-Doped Fiber Laser at 1750 nm
摘要： In recent years, the popular thulium-doped fiber lasers (TDFL) are expanding their operational wavelength coverage through accessing the 1.7-μm region, where they have previously been hindered by the quasi-three-level nature of TDF emission, which leads to strong re-absorption of short wavelength light. This was driven by a plenty of applications such as deep bio-imaging, spectroscopic analysis and material processing that takes advantages of the third near-infrared (NIR3) optical window (1600–1870 nm) for bioimaging and abundant molecular absorptions in this spectral region. At present, short wavelength TDFLs have been demonstrated to operate in the continues-wave (CW), soliton mode-locking and gain-switching regimes. Here we report a TDFL that demonstrates dissipative soliton resonance (DSR) at 1750 nm with a maximum single pulse energy of 321.2 nJ.
关键词： high energy,thulium-doped fiber lasers,1750 nm,1.7-μm region,dissipative soliton resonance
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) - Ghz-Bursts and Ultrafast External Modulation of Femtosecond Fiber Lasers with kW Average Power Levels
摘要： State-of-the-art ultrafast materials processing applications impose strong requirements on the driving laser systems. For novel ablation schemes GHz-bursts are necessary to operate ideally [1,2]. Additionally, fast modulation and control of these pulse trains is required allowing for both high-power operation (kW of average powers and mJ pulse energies) and, ideally, pulse-to-pulse amplitude control. Here we present novel solutions to address these demands based on fiber-laser technology and coherent beam combination. A standard approach to generate GHz-pulse bursts is to use a seed oscillator with a GHz repetition rate emitting a continuous pulse train and employ a pulse picker to generate the burst afterwards. Although this approach is easy to implement, it is relatively inflexible and imposes strong requirements on the pulse picker. The approach presented herein bases on a state-of-the-art MHz-level oscillator followed by a standard pulse picker. The pulse burst is generated using cascaded fiber-based delay lines (see Fig. 1). This method allows for intra-burst repetition rates >10GHz with variable pulse numbers at flexible repetition rates. Furthermore, the implementation of ultra-fast switches into high-power material processing devices is of high demand. Although there has been progress in recent years, switching and modulation of high-power laser systems is still an extreme technological challenge. Typical solutions for fast switching up to the GHz level force a trade-off between speed and high-power capability. The novel approach presented herein bases on the coherent combination of at least two parallelly working amplifier channels that are coherently combined prior the CPA compressor. Coherent combination technology has been used so far as a power-scaling concept [3] allowing to increase average power and output energy of a laser system linearly with the number of combined channels. However, it also enables fast switching of the output port by changing the phase between the two interferometrically combined amplifier channels. The advantage of this approach is that the switching element (such as an fiber-coupled electro-optical modulator) can be integrated at an early low-power stage of the system, while it actually performs as an external modulator placed at the system output. However, at the output position, only a power-scalable beam combining element has to be employed.
关键词： kW average power levels,GHz-bursts,ultrafast external modulation,femtosecond fiber lasers
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) - Saturable Absorption with CNT Coupled WGM and Fabrication of Er-Doped Microresonator for on-Chip Mode-Locked Laser
摘要： Mode-locked (ML) fiber lasers are becoming key components in industry, because they provide high performance while being relatively inexpensive. The generation of high-repetition rate pulses is gaining interest but it remains a challenge to achieve a GHz repetition rate with fiber lasers. On the other hand, whispering-gallery-mode (WGM) microresonators allow the strong confinement of light and miniaturizing an ML laser into a WGM microresonator will enable us to achieve a high pulse repetition rate, a small footprint and on-chip integrability. In this work, we explore the possibility of a passive ML laser with the system shown in Fig. 1(a). There are two key technologies involved; one is saturable absorption (SA) and the other is laser gain in a microresonator. First, we verified numerically that we could realize an ML laser with our proposed carbon nanotube (CNT) coupled erbium (Er) doped microresonator, and the result is shown in Fig. 1(b). We modelled our system with a nonlinear Schr?dinger equation, where we took gain and SA (also loss (Q), Kerr effect, and dispersion) into account [2]. The result shows that a self-starting ML is possible with microresonator parameters. Next, encouraged by the numerical result, we experimentally demonstrated SA in a microtoroid. We grew CNTs selectively on a silica microtoroid by chemical vapor deposition and investigated the SA behavior (Fig. 1(c)). By performing a pump-probe like experiment we successfully characterized the SA behavior in a microresonator system. This is the first demonstration of SA in a WGM microcavity system [1]. We then fabricated an Er-doped active microtoroid by using the sol-gel method. The sol-gel method is one way of forming silica from a metal alkoxide precursor. Although sol-gel has been widely used, it is still a challenge to fabricate high-quality defect-free film on a Si wafer that allows us to fabricate an ultrahigh-Q WGM microresonator. Figure 1(d)-(f) shows the fabricated films. We found optimum parameters and obtained a clean film as shown in Fig. 1(g). By using this film, we fabricated an Er-doped WGM microresonator, where the Q was 1.2×106 at 1480 nm (Fig. 1(h)). We obtained clear up-conversion luminescence when we pumped the cavity at 1480 nm, which constitutes the first step towards ML lasing in such a WGM microresonator. In summary, these results provide a promising approach for realizing an on-chip high repetition rate ML WGM microresonator.
关键词： saturable absorption,sol-gel method,carbon nanotube,whispering-gallery-mode microresonators,erbium-doped microresonator,Mode-locked fiber lasers
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) - Rare-Earth Doped Oxide Glasses and Fibers for Lasers Emitting in the 2÷3 μm Spectral Range
摘要： The aim of this investigation is the search of novel promising materials for solid-state and fiber lasers emitting in the spectral range 2÷3 microns, i.e. out of the range where the well-developed rare-earth doped silica fibers can successfully operate. We have stopped our choice on tellurite and calcium aluminate glasses. In contrast to silica glasses, both these glass types can contain high (>1021 cm-3) amounts of rare earth dopants. In contrast to ZBLAN glass that is widely used for mid-infrared fiber lasers, both tellurite and aluminate glasses can be quite stable to air moisture. Furthermore, calcium aluminate glasses are prominent for their extraordinary mechanical properties (better than those of fused silica). Our spectral investigations have shown that deeply dehydrated tellurite glasses (TG) are very suitable hosts for 2.3 μm Tm3+ lasers and can be also used as a host for 2.7 μm Er3+ lasers. As for calcium aluminate glasses (CAG), their phonon spectrum is not suitable for 2.7 for μm lasers. But the emission properties of Tm3+ ions in this host show some unusual feature. Two-micron Tm3+ emission band in CAG is anomalously widened and red shifted so that it overlaps well with the 2.3μm emission band. Thus continuous tuning of Tm doped CAG fiber laser from ~2μm up to ~2.4μm is conceivable. Figures 1 and 2 give some examples of bulk Tm-doped TG and CAG lasing properties. Fig. 1 shows the 2.3μm lasing parameters of 30 mm long TG sample when pumped by a pulsed ruby laser. CAG in similar conditions showed cascade lasing at 2.3μm and 2.1μm. Fig. 2 shows the lasing parameters of a quasi CW diode-pumped CAG chip laser, operating at the wavelength of 2.1 μm. Surely most practical applications of such laser glasses require fiber configuration. We have developed the laboratory technology of TG multimode and single-mode double-cladding fibers fabrication. In Tm doped TG fibers laser action at 1.9 μm and 2.3 μm was successfully demonstrated. Er doped fibers were also manufactured but 2.7 μm laser action in them requires highly reflective fiber Bragg gratings to be made in them. Fabrication of CAG fibers is a very complicated technological task due to high tendency of CAG to devitrification. Nevertheless, using “rod-in-tube” method we have prepared an optical fiber starting from Tm-doped CAG rod in a silica tube. Unfortunately, the core of this fiber contained too much SiO2 diffused from the cladding. The choice of a suitable lower-melting cladding glass should solve the problem. Thus, the properties of deeply dehydrated rare-earth doped tellurite and calcium-aluminate glasses are shown to be quite pertinent for lasers emitting in the 2÷3 μm spectral range.
关键词： rare-earth doped oxide glasses,mid-infrared spectral range,fiber lasers,tellurite glasses,calcium aluminate glasses
更新于2025-09-11 14:15:04
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Super Gaussian pulse generation in a passively mode-locked fiber laser
摘要： The generation of self-similar super Gaussian-like pulses from a passively mode-locked fiber laser is numerically demonstrated. The laser cavity utilizes a long period fiber grating as a pulse-shaping element. The model is based on the normalized complex Ginzburg-Landau equation and the nonlinear coupled mode equations of the grating. The numerical results show stable super Gaussian pulses with a linear frequency chirp, a 1.5 ps pulse duration and 2 nJ energy. The generated pulses are scalable and exhibits no bifurcation or instability as the gain is increased.
关键词： Mode-locked fiber lasers,Ginzburg-Landau equation,Kerr nonlinearity,Self-similar pulses,Numerical methods
更新于2025-09-11 14:15:04
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Enhanced Pump Absorption Efficiency in Coiled and Twisted Double-Clad Fibers for Fiber Lasers
摘要： High-power operation of fiber lasers was mainly enabled by the invention of cladding-pumping in a double-clad fiber structure. Pump absorption is enhanced by broken circular symmetry of inner cladding cross-sections and by mode-scrambling of the pump modes resulting from unconventional fiber coiling. However, theoretical studies were limited to the assumption of a straight fiber until recently, when the rigorous model accounting for double-clad fiber bending and twisting was described. It was found that squeezing of the effective area of the pump radiation due to fiber bending plays an important role in cladding-pump absorption enhancement. We review results of numerical modeling of pump absorption in various types of double-clad fibers, e.g., with cross-section shape of hexagon, stadium, and circle; two-fiber bundle (so-called GTWave fiber structure) a panda fibers are also analyzed. The presented results can have a practical application and potential impact in the construction of fiber lasers: with pump absorption efficiency optimized by our new model (the other models did not take into account fiber twist), the double-clad fiber of shorter length can be used in the fiber lasers and amplifiers. This dramatically minimizes the deleterious effect of background losses and nonlinear effects.
关键词： fiber lasers,thulium-doped fibers,rare-earth-doped fibers,optical pumping
更新于2025-09-11 14:15:04