- 标题
- 摘要
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- 实验方案
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Holmium oxide thin film as a saturable absorber for generating Q-switched and mode-locked erbium-doped fiber lasers
摘要： We demonstrated a new type of transition metal oxide (TMO) material, Holmium oxide (Ho2O3) polymer ?lm SA for compact passively Q-switched and mode-locked erbium-doped ?ber laser (EDFL) generations. The ?lm SA has a thickness of ~40 μm and modulation depth of ~45%. It was fabricated by embedding Ho2O3 nanoparticles into PVA polymer solution. The Q-switched laser operated stably at a center wavelength of 1563 nm within a pump power range of 45–97 mW. The maximum Q-switching pulse repetition rate and the narrowest attainable pulse width were 115.8 kHz and 0.64 μs, respectively; while, the maximum pulse energy was obtained as 129.36 nJ. On the other hand, the mode-locked EDFL emerged stably within a pump power range of 62–180 mW at a center wavelength of 1565.4 nm. The repetition rate was 17.1 MHz, while the pulse width was 650 fs. Additionally, the maximum output power was measured as 9.01 mW; while, the corresponding maximum pulse energy was obtained as 0.524 nJ. This Ho2O3 ?lm SA o?ers simplicity and reliability in the design of compact and portable ?ber pulsed laser generators particularly in the 1.55-μm regime.
关键词： Mode-locked,Saturable absorber,Q-switched,Ho2O3,ERBIUM-doped ?ber laser
更新于2025-09-16 10:30:52
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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) - Mode Re-Locking in an RF Detuned Actively Mode-Locked Fiber Ring Laser
摘要： RF detuning of the actively mode-locked ?ber ring laser (AMLL) causes deterioration in its performance due to lock-loss of higher cavity modes [1, 2]. The effects of detuning are typically mitigated by either modifying the cavity or using additional optical components [3]. We demonstrate an improvement in the performance of the detuned AMLL using multiple RF input signals without altering the cavity while achieving an extension of the injection range of the modes and increasing number of locked modes.
关键词： Lasers, injection-locked,Lasers, fiber,Laser theory,Mode-locked lasers
更新于2025-09-12 10:27:22
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Experimental exploration of mode-locking evolution mechanism in dual-ring fiber laser
摘要： We explored experimentally the mode-locking (ML) evolution mechanism of a dual-ring fiber laser. Increase of the total pump power up to 860 mW allowed the observation of the state changes from single-ring ML, dual-ring ML, to dual-ring self-starting ML. Moreover, a group of wave plates and a fixed polarization beam splitter were applied in each subring as precise attenuators. Rotation of each wave plate for an entire turn allowed the investigation of the ML evolution of the two subrings based on the intracavity power variation in each subring. The variation periodicity of the output power was analyzed for each subring and was found to be consistent with the theoretical results. Furthermore, the ML detachment threshold in each subring was estimated to explain the ML evolution. Our study provides a deeper understanding of the ML evolution in dual-ring fiber lasers and can aid their future optimal design for dual comb applications.
关键词： Fiber lasers,Mode-locking evolution,Cascaded nonlinear processes,Mode-locked lasers,Ultrafast mechanism
更新于2025-09-12 10:27:22
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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) - Self-Injected Optical Frequency Comb Quantum Dash Lasers
摘要： Self mode-locked (SML) quantum dash (QDh) lasers emitting at around 1550 nm are compact broadband optical frequency comb (OFC) sources for multi-wavelength communication applications [1,2]. Optical self-feedback (OFB) by auxiliary cavities with lengths in the meter-range is a well-established method for a precise and dynamical mode spacing control of passively mode-locked (PML) semiconductor lasers. Recent works focused on identifying maximum tuning ranges of quantum well PML lasers and suggested that external OFB length, interaction width of fed-back pulse with the pulse inside the laser cavity and the OFB strength appear predominant [3]. In this contribution, we experimentally investigate and explain by modeling the dependence of mode spacing of OFB of SML QDh lasers subject to different cavity lengths on the external optical delay. Here, we study the impact of different OFB strengths and external OFB cavity lengths onto the mode spacing of QDh SML lasers. The three lasers investigated are 1 mm and 2 mm long, corresponding to a mode spacing of 40 GHz and 20 GHz, base on 6 and 9 layers of InAs/InGaAsP Qdhs [1,4] and exhibit as-cleaved facets. In the developed experimental set-up, sketched in Fig. 1a), the laser light is coupled into a lensed single-mode fiber and a part of the light is directed to the hybrid fiber based and free-space OFB cavity.
关键词： mode spacing control,optical frequency comb,self mode-locked,optical self-feedback,quantum dash lasers
更新于2025-09-12 10:27:22
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Phase Noise Measurements and Performance of Lasers with Non-white FM Noise for Use in Digital Coherent Optical Systems
摘要： We measure the FM noise power spectral density of quantum-dot mode-locked lasers (QD-MLLs) and compare this to their measured linewidths as predictors of performance in a digital coherent system. We explain our observations in terms of the non-Lorentzian line shape of the source wherein linewidth is determined by the low frequency part of its FM noise. Investigation of system performance with simulations based on the measured phase sequences and back-to-back coherent transmission experiments, show that QD-MLLs with linewidths of several MHz can have comparable performance to that of a laser with only a few hundreds of kHz of Lorentzian linewidth, due to the non-white part of their FM noise. We show that spectral linewidths of lasers with similar spectral properties can underestimate their performance in coherent systems, regardless of the linewidth measurement technique used. We propose a “Lorentzian-equivalent linewidth” measure to characterize lasers with non-white FM noise and to estimate their impact in digital coherent optical systems. This measure is obtained from phase variations at frequencies higher than typical frequencies often used to characterize lasers with white FM noise, and comparable to the system baud. The proposed measure is shown to be a better predictor of system performance than the measured linewidth, for lasers with non-white FM noise. The impact of non-white FM noise on the optimization of carrier phase recovery and system performance is also discussed.
关键词： diode lasers,Coherent communication,optical fiber communication,mode-locked lasers
更新于2025-09-12 10:27:22
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Breathing dissipative solitons in mode-locked fiber lasers
摘要： Dissipative solitons are self-localized coherent structures arising from the balance between energy supply and dissipation. Besides stationary dissipative solitons, there are dynamical ones exhibiting oscillatory behavior, known as breathing dissipative solitons. Substantial interest in breathing dissipative solitons is driven by both their fundamental importance in nonlinear science and their practical applications, such as in spectroscopy. Yet, the observation of breathers has been mainly restricted to microresonator platforms. Here, we generate breathers in a mode-locked fiber laser. They exist in the laser cavity under the pump threshold of stationary mode locking. Using fast detection, we are able to observe the temporal and spectral evolutions of the breathers in real time. Breathing soliton molecules are also observed. Breathers introduce a new regime of mode locking into ultrafast lasers. Our findings may contribute to the design of advanced laser sources and open up new possibilities of generating breathers in various dissipative systems.
关键词： spectroscopy,breathing solitons,mode-locked fiber lasers,dissipative solitons,nonlinear science
更新于2025-09-12 10:27:22
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Acousto-optic mode-locked Tm:LuAG laser with nearly diffraction-limited beam
摘要： We reported an acousto-optic mode-locked Tm:LuAG laser pumped by a 786? nm laser diode and realized continuous-wave mode-locked operation. At the pump power of 8.2?W, the output average power was 335 mW with the wavelength of 2023.2?nm. The pulse width was 240?ps at the pulse repetition frequency of 81.60?MHz, and the beam quality factor M2 was 1.04. The output wavelength was tuned from 2022.6 to 2025.3?nm, corresponding to the output average power of 310 to 353 mW. In addition, the self-mode-locking phenomenon was found.
关键词： Solid-state lasers,Actively mode-locked,Thulium laser,Infrared laser
更新于2025-09-12 10:27:22
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Microfiber-Knot-Resonator-Induced Partial Elimination of Longitudinal Modes in fiber lasers for in-Tune-Switchable Nanosecond Pulse Generation
摘要： By incorporating a house-made microfiber knot resonator (MKR), mode-locking regime transformation in an erbium-doped fiber (EDF) laser was achieved. With typical nonlinear polarization rotation (NPR) as the mode-locker, ~890 fs soliton pulses could be directly produced from the EDF laser. However, once the MKR was further incorporated in it, the emitted pulse duration fell into the nanosecond regime, and meanwhile the spectral bandwidth dramatically narrowed down around 0.05 nm. This resulted from that the longitudinal laser modes were greatly eliminated by the MKR. The MKR exhibits tightly-packed, extremely narrow transmission teeth, acting as a comb-like, sharp-rolloff bandpass filter. The mode elimination factor could reach ~98.81%. Further manipulating the intra-cavity polarization state, the emission wavelength could be switchable from one of the transmission teeth of the MKR to another, due to the intrinsic polarization-sensitivity of the NPR. Our results demonstrated that MKR could be a useful device in fiber lasers to enable some artificially pre-defined spectral and temporal characteristics through pre-designing on the related parameters of the MKR. This could also provide a route to transform the temporal characteristics through tailoring the spectral profile, i.e., manipulating the permitted longitudinal laser modes, in fiber lasers.
关键词： Microfiber knot,mode-locked,Fiber lasers
更新于2025-09-12 10:27:22
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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) - 4.37 GHz L-Band Passively Harmonic Mode-Locked Fiber Laser Based on Nonlinear Polarization Rotation
摘要： L-band passively harmonic mode-locked (PHML) fiber lasers are important because various practical applications, such as high-speed optical sampling, dense wavelength division multiplexed (DWDM) systems and material processing, etc. Therefore, L-band PHML fiber lasers have been widely concerned in recent years. In 2012, J. Du et al experimentally achieved L-band PHML pulses by utilizing graphene as a saturable absorber (SA) [1]. Under a certain pumping power, 2nd to 4th harmonic orders can be tuned by adjusting polarization controllers (PCs). In 2014, Y. Meng et al obtained 5.88 GHz L-band PHML pulses with 19 dB super-mode suppression ratio (SMSR) in an Er-Yb co-doped double-clad fiber laser using a graphene SA [2]. In 2018, Q. Huang et al built up a 550 MHz L-band PHML fiber laser based on carbon nanotubes film for the first time [3]. It is worth noting that all of these results are focused on the generation of L-band PHML by utilizing a physical SA. However, the fabrication of physical SA can be complicated with high cost and its thermal damage threshold is not enough to support high pump power which have great impact on the repetition rate of harmonic pulses. Meanwhile, nonlinear polarization rotation as an effective SA have many advantages including high thermal damage threshold, low fabrication cost, high modulation depth and compactness. Therefore, it is desirable to build an L-band PHML fiber laser based on NPR.
关键词： fiber laser,nonlinear polarization rotation,passively harmonic mode-locked,L-band
更新于2025-09-12 10:27:22
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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) - Controllable Generation of Ultrashort Multi-Bound Solitons in a Mode-Locked Erbium-Doped Ring Laser with a Highly-Nonlinear Resonator
摘要： Mode-locked (ML) ultrashort pulse (USP) fiber lasers can be treated as an ideal platform to expand future applications due to a complex nonlinear dynamics with a presence of a high value of a group velocity dispersion and a third-order dispersion in the laser resonator. Up to now a series of novel ML regimes have been investigated e.g. self-similar pulses, noise-like pulses, multi-bound solitons, and a soliton rain generation. Multi-bound solitons (MBS) generation regime, also known as soliton molecules, is of considerable interest in various fields of applications. For example, the investigation of a MBS generation is very attractive for increasing the data transfer capacity in telecommunications due to coding alphabet extension. The coding concept of MBS suggests a data stream using more than two symbols (2?N symbols, where N is the number of generated solitons in a bound state) [1]. And also, recent research shows that using ultrafast bursts of pulses can improve the quality of laser ablation for medical applications [2]. Moreover, MBS generation can be also used in a coherent pulse staking amplification scheme increasing an amplification efficiency along with a formation of high-energy solitons at a high-repetition-rate [3]. Previously we have obtained a generation of stable low-noise ultrashort multi-bound solitons in a passive mode-locked all-fiber erbium-doped ring laser with a highly-nonlinear resonator [4]. Fig. 1 shows autocorrelation traces and spectrums of MBS generation obtained by pump power variation at a wavelength of 980 nm. The output spectrums are evidently showing high-contrast intensity fringes (up to ~20 dB) and autocorrelation traces having symmetrical form without additional intensity peaks that indicates a stable and strong coherent connection between ultrashort pulses and fixed coherent phase difference in the temporal domain between several identical pulses. It is known that the highest energy of a fundamental soliton in a laser resonator with duration τp is limited by the soliton area theorem Es ~ |β2|/(γ · τp), where γ is the net nonlinear coefficient and β2 is the total cavity dispersion [1]. Soliton energy quantization results in pulse splitting at operation powers higher than the fundamental limit. Here we experimentally demonstrate the formation multi-bound solitons with the controllable number of bound states 7 < N < 17 by pump power variation in the range from ~160 mW to ~377 mW obtained in a highly-nonlinear fiber ring cavity.
关键词： ultrashort pulse,laser ablation,fiber lasers,Mode-locked,coherent pulse staking amplification,soliton molecules,telecommunications,multi-bound solitons
更新于2025-09-12 10:27:22