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- 摘要
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- 实验方案
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Fe <sub/>3</sub> O <sub/>4</sub> nanoparticles as the saturable absorber for a mode-locked fiber laser at 1558 nm
摘要： We demonstrated a mode-locked erbium doped fiber laser (EDFL) operating at 1558 nm by exploiting ferroferric-oxide nanoparticles (FONPs) as the saturable absorber (SA) material. FONPs, with an average diameter of ~20 nm, were prepared by a thermal decomposition method, then mixed with sodium carboxymethylcelluose to form an FONP film. The FONP SA was fabricated through a sandwiched FONP film between two fiber connectors. By inserting the FONPs SA into an EDFL cavity pumped by a 980 nm laser diode, stable passive mode-locking was achieved with a threshold pump power of ~120 mW. The obtained mode-locked laser had a central wavelength of ~1558 nm, a spectral bandwidth of ~0.8 nm, a pulse width of ~4.35 ns, and a repetition rate of ~37.32 MHz. Furthermore, a maximum average power of ~17 mW was obtained for a pump power of 340 mW. To the best of our knowledge, this is the first time that it has been demonstrated that FONPs can be used for constructing mode-locked fiber lasers.
关键词： mode-locked,fibre laser,Fe3O4 nanoparticles,saturable absorber (SA)
更新于2025-11-28 14:23:57
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Passively Q-switched erbium-doped fiber laser using quantum dots CdSe embedded in polymer film as saturable absorber
摘要： We demonstrate a passively Q-switched erbium doped fiber laser (EDFL) based on quantum dots (QD) CdSe as a saturable absorber (SA). The synthesized CdSe powder was embedded into a poly(methyl methacrylate) (PMMA) using emulsion polymerization process. The film is sandwiched between two fiber connector via an adapter to form a fiber-compatible SA device. By integrating the SA device into the EDFL ring cavity, the stable Q-switched operation is achieved at 1559.35 nm as the pump power is varied within 30–118 mW. The laser has a pump threshold of 20.4 mW. The pulse repetition rate shows an increasing trend from 33.2 to 68.45 kHz, whereas the pulse width exhibits a decreasing trend from 10.04 to 4.30 μs as the pump power is increased from 30 to 118 mW. The highest pulse energy of 11.83 nJ is obtained at a pump power of 118 mW. These results indicate that QD CdSe is a promising SA for Q-switching laser operation.
关键词： Q-switching,Quantum dots CdSe,Saturable absorber
更新于2025-11-28 14:23:57
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Molybdenum tungsten disulphide (MoWS <sub/>2</sub> ) as a saturable absorber for a passively Q-switched thulium/holmium-codoped fibre laser
摘要： In this work, a passively Q-switched Thulium/Holmium-doped fibre laser (THDFL) using a molybdenum tungsten disulphide (MoWS2) saturable absorber (SA) is proposed and demonstrated. The MoWS2 nanosheets are prepared by hydrothermal exfoliation and then suspended in a polyvinyl alcohol (PVA) thin film host. Q-switching of the THDFL at a maximum 1550 nm pump power of 445.2 mW gives a maximum repetition rate and minimum pulse width of 36.3 kHz and 2.8 μs with a corresponding pulse energy of 86.4 nJ and peak power of 31.1 mW. The MoWS2 based Q-switched THDFL’s output has a very high signal-to-noise value of ～ 62.2 dB which strongly indicates that the laser is working in a stable operation. To the best of our knowledge, this is the first demonstration of MoWS2 as a passive SA in a THDFL for operation in the 2.0 μm region. The proposed laser would have significant medical and sensing applications, particularly at the biologically active 2.0–2.1 μm regions.
关键词： thulium/holmium-doped fibre,transition metal dichalcogenides,Saturable absorber,Q-switching
更新于2025-11-28 14:23:57
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Newly developed chromium-doped fiber as a saturable absorber at 1.55- and 2.0-μm regions for Q-switching pulses generation
摘要： We demonstrate a Q-switching operation laser at 1.55- and 2-μm region using a homemade 10 cm long of Chromium-doped ?ber (CrDF) as a passive saturable absorber (SA). Erbium-doped ?ber (EDF) and Thulium-doped ?ber (TDF) as a gain medium cooperate in the all-?ber ring cavity con?guration. CrDF was fabricated by Modi?ed Chemical Vapour Deposition (MCVD) technique in conjunction with conventional solution doping (SD) method. The CrDF has a saturable absorption of 9% at 1.55-μm region with a saturation intensity of 22 MW/cm2. Therefore, a stable pulse train obtainable within 75–173 mW, with a repetition rate increases from 68.12 kHz to 115.9 kHz. At the maximum pump level, a shorter pulse width, maximum output power, and maximum pulse energy are 3.85 μs, 10.86 mW, and 94.1 nJ, respectively. In TDF laser cavity, the laser pulsing generates from 363 mW to 528 mW, where the repetition rate increases from 13.02 kHz to 27.62 kHz. At maximum pump power, a shorter pulse width, maximum output power, and pulse energy are obtained with 4.48 μs, 6.36 mW, and 230.27 nJ, respectively. Both pulse trains at 1.55- and 2-μm region are stable with a signal-to-noise ratio (SNR) of 71 dB and 44 dB, respectively. These ?ndings are important to the discovery of robust passive saturable absorber development in a form of ?ber which has a similar melting point to the rest of the silica ?ber in the proposed cavities. Thus, it will be a kick-started to alternative form of passive SAs in developing a future high-power ?ber lasers.
关键词： Pulse laser,Ring cavity,Chromium-doped ?ber saturable absorber,Fiber laser
更新于2025-09-23 15:22:29
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Tm-doped all-fiber structured femtosecond laser mode-locked by a novel Chem-Te saturable absorber
摘要： We succeed in developing a chemically synthesized tellurium nanocrystals (Chem-Te) thin film by liquid phase peeling technique, and demonstrate this material is an effective saturable absorber (SA) for realization of stable mode-locking in an all-fiber structured thulium-doped laser cavity. By integrating this SA into an all-fiber structured ring laser cavity, we obtained the mode-locked pulses at the repetition rate of 11.17 MHz, the achieved pulses spectral bandwidth FWHM (full width at half maximum) of 5.26 nm and the pulses duration of 890 fs with 620 mW pump power at 1560 nm, the fundamental mode-locked laser output power as high as 5.35 mW. In addition, by further increasing the pump power, the second-order and third-order harmonic mode-locked pulses train of this fiber laser were also observed. To the best of our knowledge, this is the first report on the novel Chem-Te material saturable absorption property realization in 2 μm-band fiber laser system.
关键词： Femtosecond laser,Saturable absorber,Chem-Te,Mode-locked
更新于2025-09-23 15:21:01
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Conventional solitons and bound-state solitons in an erbium-doped fiber laser mode-locked by TiSe2-based saturable absorber
摘要： Conventional solitons (CSs) as well as bound-state solitons in a passively mode-locked erbium-doped fiber (EDF) laser based on 1T-phase titanium diselenide (1T-TiSe2) saturable absorber (SA) have been systematically demonstrated for the first time. The mode locker is assembled by sandwiching the 1T-TiSe2 film between two fiber ferrules to improve compatibility with the all-fiber-integrated ring cavity configuration. The modulation depth, saturation intensity and nonsaturable loss of the prepared 1T-TiSe2 SA are 14.36 %, 1.33 MW/cm2 and 9.44 %, respectively. The system, by means of carefully adjusting the orientations of the polarization controller (PC), is switchable between two states: CS and bound-state CS. In the CS mode-locked regime, the oscillating wavelength is centered at 1558.294 nm with a pulse duration of 1.74 ps, a pulse repetition rate of 3.23 MHz and a maximum average output power of 2.904 mW, respectively. In the bound-state CS regime, two identical solitons form the bound-state pulses with a temporal separation of 6.1 ps, and the bound-state pulses are equally distributed at a repetition rate of 3.23 MHz, corresponding to the fundamental cavity repetition rate. The experimental results further indicate that 1T-TiSe2 SA is competitive to the existing SAs explored so far and will promote the applications of 1T-TiSe2-based SAs in the field of ultrafast lasers.
关键词： bound-state pulses,erbium-doped fiber (EDF) laser,mode-locked fiber laser,1T-phase titanium diselenide (1T-TiSe2),soliton pulses,saturable absorber (SA)
更新于2025-09-23 15:21:01
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Nonlinear Optics || Nonlinear Optics in the Two-Level Approximation
摘要： Our treatment of nonlinear optics in the previous chapters has for the most part made use of power series expansions to relate the response of a material system to the strength of the applied optical field. In simple cases, this relation can be taken to be of the form ?P (t) = (cid:2)0χ (1) ?E(t) + (cid:2)0χ (2) ?E(t)2 + (cid:2)0χ (3) ?E(t)3 + · · · . However, there are circumstances under which such a power series expansion does not converge, and under such circumstances different methods must be employed to describe nonlinear optical effects. One example is that of a saturable absorber, where the absorption coefficient α is related to the intensity I = 2n(cid:2)0c|E|2 of the applied optical field by the relation α = α0 / (1 + I /Is), where α0 is the weak-field absorption coefficient and Is is an optical constant called the saturation intensity. We can expand this equation in a power series to obtain α = α0 [1 ? (I /Is) + (I /Is)2 ? (I /Is)3 + · · · ]. However, this series converges only for I < Is, and thus only in this limit can saturable absorption be described by means of a power series of the sort given by Eq. (6.1.1).
关键词： Rabi oscillations,two-level approximation,saturable absorber,optical Stark shifts,nonlinear optics
更新于2025-09-23 15:21:01
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TiOxNy Thin Film Sputtered on a Fiber Ball Lens as Saturable Absorber for Passive Q-Switched Generation of a Single-Tunable/Dual-Wavelength Er-Yb Double Clad Fiber Laser
摘要： The use of titanium oxynitride (TiOxNy) thin ?lms as a saturable absorber (SA) element for generation of passive Q-switched (PQS) laser pulses, from a linear cavity Er-Yb double-clad ?ber (EYDCF) laser, is demonstrated. Additionally, the deposition of the material as a thin ?lm covering a ?ber micro-ball lens (MBL) structure is reported for the ?rst time. The TiOxNy coating is deposited by a direct current (DC) magnetron-sputtering technique. The MBL is inserted within the laser cavity in a re?ection con?guration, alongside a re?ecting mirror. As a result, the coated ?ber MBL simultaneously acts as a SA element for PQS laser pulses generation and as an interference ?lter for wavelength selection and tuning of the generated laser line. Tunable single-laser emission in a wavelength range limited by dual-wavelength laser generation at 1541.96 and 1547.04 nm is obtained. PQS laser pulses with a repetition rate from 18.67 to 124.04 kHz, minimum pulse duration of 3.57 μs, maximum peak power of 0.359 W, and pulse energy of 1.28 μJ were obtained in a pump power range from 1 to 1.712 W.
关键词： Q-switched ?ber lasers,titanium oxynitride,DC magnetron sputtering,?ber micro-ball lens,saturable absorber materials
更新于2025-09-23 15:21:01
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Observation the Multi-Soliton Patterns From the Er-Doped Mode-Locked Fiber Laser Modulated by PtSe2
摘要： The passively mode-locked ?ber laser modulated by low-dimensional materials can provide an ideal platform to investigate the soliton dynamics. Here, we experimentally explored the soliton formation and evolution from an erbium-doped ?ber laser mode-locked by mechanically exfoliated PtSe2 saturable absorber via evanescent ?eld interaction. With the increasing pump power, different soliton patterns, such as single soliton, two solitons, and bound soliton, can be observed experimentally. The experimental results can identify the non-linear optical response of the PtSe2 and may make avenue toward unveiling the nature of the soliton dynamics in the ?ber laser system.
关键词： non-linear optics,soliton dynamics,?ber laser,mode-locking,saturable absorber
更新于2025-09-23 15:21:01
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Cuprous Sulfide for Different Laser Pulse Generation: Q-Switching and Mode-Locking
摘要： As a new type of copper-based chalcogenide two-dimensional nanomaterial, cuprous sulfide (Cu2S) has attracted much attention due to its unique band structure and optical properties. In this paper, all-fiber ring laser at the 1.53 μm regime with two kinds of Cu2S saturable absorber devices is demonstrated. The self-started Q-switched pulse with a central wavelength of 1530 nm was obtained for the first time by using Cu2S deposited on the fiber jumper as SA. When the tapered fibers deposited with Cu2S are used to replace the jumpers in the cavity, it can be found that the loss is significantly reduced and a mode-locked pulse with a pulse width of 896 fs has been achieved via evanescent field interaction. This experiment further enriches the application of Cu2S nanosheets in pulsed lasers and promotes the development and application of metal sulfides in nonlinear optics and ultrafast photonics.
关键词： saturable absorber,cuprous sulfide,mode-locking,Q-switching,ultrafast photonics,Cu2S,nonlinear optics
更新于2025-09-23 15:19:57