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Stable injection locking with slotted Fabry–Perot lasers at 2 <i>μ</i> m
摘要： Injection locking has many applications in telecommunications systems, such as narrowing linewidths, increasing bandwidth and improving filtering. Beyond telecommunications, injection locking is widely used in remote sensing. This is of particular interest for applications in the 2 μm region, where gases such as carbon dioxide, water vapour and methane have identifiable absorption features. In this paper, we demonstrate stable injection locking with slotted Fabry–Perot lasers in the 2 μm wavelength region. Injection locking was observed in both the optical domain and power spectrum; with key features recorded such as injection ‘pulling’, side-mode suppression and the characteristic quiet region in the electrical domain denoting single-frequency emission and stable locking. The effect of varying the injection ratio was investigated, with a decreased injection ratio corresponding to a reduction in the locking bandwidth. Finally, the lasers were shown to remain injection locked, with no thermal drift, for over 24 h, indicating their suitability for implementation in a real-world telecommunications system.
关键词： injection-locked lasers,semiconductor lasers,optical communications,optical sensing and sensors
更新于2025-11-28 14:23:57
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Large diameter coreless fiber as a saturable absorber for erbium doped fiber laser cavity based on multimode interference
摘要： We demonstrated a Q-switched erbium-doped fiber laser (EDFL) based on large diameter coreless fiber without intra-cavity tuning element for the first time. A single mode fiber –coreless fiber –single mode fiber (SNCFS) structure was employed as a passive Q-switcher relies on Kerr nonlinearity associated with multi-mode interference (MMI) effect. By splicing 10 cm of 125 μm in diameter coreless fiber (NCF) between two single mode fibers (SMFs), C-band Q-switched EDFL with 3-dB bandwidth of 0.138 nm was successfully obtained, making it a simple, compact and easily handling modulation device. A stable Q-switched pulses were achieved with a pump threshold of 188 mW. Pulse repetition rate ranges from 73.3 to 92.0 kHz, minimum pulse width of 3.5 μs and maximum energy of 50.9 nJ were recorded.
关键词： Q-switched,Fiber lasers,Multimode interference
更新于2025-11-28 14:23:57
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Fiber laser based on a fiber Bragg grating and its application in high-temperature sensing
摘要： A fiber laser based on an FBG fabricated by femtosecond laser and a Sagnac loop as cavity mirrors is demonstrated. The fiber laser can work stably as a temperature sensor at 1000 ℃ after the FBG was annealed at 1100 ℃. The wavelength of the fiber laser had a quadratic dependence on temperature from room temperature to 1000 ℃. The temperature–wavelength had a good linear relationship from 300 ℃ to 1000 ℃. Its sensing sensitivity was about 15.9 pm/℃.
关键词： Optical fiber lasers,Fiber Bragg gratings,High temperature sensors
更新于2025-11-28 14:23:57
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Construction of 879?nm direct intra-cavity pumped dual-wavelength laser operating at 912?nm and 1064?nm
摘要： A dual-wavelength continuous-wave laser with direct intra-cavity pumping using a 879 nm laser diode that utilizes Nd:GdVO4 and Nd:YVO4 crystals, is presented. To the best of our knowledge, this system completely eliminates the gain competition between the 912 nm and 1064 nm transitions for the first time. A theoretical model is introduced to describe this intra-cavity pumped dual-wavelength laser. The lasing threshold of the 912 nm Nd:GdVO4 laser is presented by considering the ground-state reabsorption loss effect. A total output power of 1.33 W at dual-wavelength operation with an absorbed pump power of 7.91 W is experimentally achieved. The individual output power for the 912 nm and 1064 nm emissions were 0.43 W and 0.9 W, respectively. Both wavelengths operate in TEM00 mode with a total slope efficiency > 20%.
关键词： Lasers,Neodymium,Dual-wavelength,Solid-state,Intra-cavity pumped
更新于2025-11-28 14:23:57
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Soliton mode-locking in thulium-doped fibre laser by evanescent field interaction with reduced graphene oxide-titanium dioxide saturable absorber
摘要： Soliton mode locking pulse generation in a thulium-doped fibre laser (TDFL) by evanescent wave interaction from a D-shaped fiber coated with rGO-TiO2 nanoparticles is proposed and demonstrated. The rGO-TiO2 nanoparticle coating serves as a saturable absorber (SA), and generates a mode locked pulse with a repetition rate, average output power and pulse width of 9.28 MHz, 11.17 nW and 1.49 ps respectively. The proposed laser has a central lasing wavelength of 1939.4 nm, which is the longest as of yet generated by evanescent wave interaction in a TDFL. An average signal-to-noise ratio of around 50 dB is obtained from the generation pulse, with minimal power and wavelength fluctuations indicating high stability. The proposed laser would have significant applications in various fields, particularly medicine for its operation in the eye-safe region of 2 μm.
关键词： soliton,fibre lasers,thulium doped fibre,mode-locking
更新于2025-11-28 14:23:57
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Bi2Te3 Topological Insulator for Domain-Wall Dark Pulse Generation from Thulium-Doped Fiber Laser
摘要： We have experimentally demonstrated domain-wall (DW) dark pulses from a thulium-doped fiber laser incorporating a topological insulator saturable absorber (SA). The bulk-structured Bi2Te3 was used as the SA, which was constructed on a fiber ferrule platform through the deposition of the Bi2Te3 mixed with distilled water. The DW dark pulses were generated from the thulium-doped fiber laser cavity with a dual wavelength at 1956 nm and 1958 nm. The dark pulse width and the repetition rate were measured as ~10.3 ns and ~20.7 MHz over the pump power of ~80 mW, respectively. To the best of our knowledge, this work is the first demonstrated generation of the DW dark pulse from a thulium-doped fiber laser using nanomaterial-based SA.
关键词： fiber lasers,Bi2Te3,topological insulator,domain-wall dark pulses
更新于2025-11-28 14:23:57
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Switchable transverse-mode operation of an actively mode-locked EDF laser based on low-modal-crosstalk mode MUX/DEMUX
摘要： In this paper, we report an all-?ber actively mode-locked erbium-doped ?ber laser based on the mode multiplexer/demultiplexer (MUX/DEMUX). Higher-order mode and mode-locked pulse outputs can be realized simultaneously. The mode-locking is achieved by using a LiNbO3 Mach–Zehnder intensity modulator. Multiple linearly polarized (LP) modes in the ring ?ber laser are generated by mode MUX/DEMUX. For different spatial modes (LP01, LP11, LP21, hybrid modes), 17.32 ns, 20.40 ns, 23.00 ns and 17.24 ns mode-locked pulse trains are successfully obtained, respectively. The output laser operates at the fundamental frequency of 8.064 MHz with center wavelengths of 1528.71 nm for LP01 mode, 1528.30 nm for LP11 mode, 1530.45 nm for LP21 mode and 1530.05 nm for hybrid mode. Moreover, we also measure the slope ef?ciency, spectrum and intensity distribution. The results show that the proposed ?ber laser has potential applications in mode-division-multiplexed systems, optical sensing and optical ?ber communication.
关键词： Mode switching,Mode MUX/DEMUX,Mode-locked ?ber lasers
更新于2025-11-28 14:23:57
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Effect of Er:YAG laser irradiation and chitosan biomodification on the stability of resin/demineralized bovine dentin bond
摘要： Objective: The purpose of this study was to evaluate the effect of Er:YAG laser for selective removal of carious lesion, followed by biomodification with chitosan on the microtensile bond strength (μTBS), adhesive interface, dry mass loss and hydroxyproline release (HYP). Methods: Artificial lesions were created in 104 bovine dentin blocks. Blocks were divided according to caries removal method: bur or Er:YAG laser. Seventy-six blocks were acid etched and subdivided according to dentin biomodification: no chitosan and 2.5% chitosan. Composite resin restorations were performed. Blocks were sectioned into beams and stored in water. After 24 h, 6 and 12 months, beams were submitted to μTBS test (n = 10) and analysis of adhesive interface by SEM (n = 3). The other 28 blocks were sectioned into beams and initial dry mass (DM) was determined (n = 7). Beams were stored and after 7 days, DM was redetermined. HYP release (n = 7) was evaluated by ELISA. Data were analyzed by ANOVA and Bonferroni's tests (α = 0.05). Results: After 24 h, the highest μTBS was found for bur (p < 0.001). After 6 months, methods were similar (p = 0.432). After 12 months, laser-irradiated dentin showed the highest μTBS values (p = 0.025). Chitosan promoted higher μTBS values after 6 (p = 0.011) and 12 months (p < 0.001) preserving adhesive interface. Dry mass loss and HYP release were not influenced (p > 0.05) by caries removal method or by dentin biomodification. Conclusion: The bond strength to demineralized dentin reduced over 50% in all groups after water storage. From 6 months of water storage, Er:YAG laser irradiation and biomodification with chitosan maintained the stability of the resin-dentin bonds, but did not influence dry mass loss and HYP release.
关键词： μTBS,Hydroxyproline,Lasers,Demineralized dentin,Collagen
更新于2025-11-21 11:18:25
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Imaging multiple Rydberg wave packets from shaper-generated two-color femtosecond pump-probe sequences
摘要： We combine a bichromatic white light polarization pulse shaping scheme with angle- and energy-resolved photoelectron spectroscopy to image the dynamics of atomic Rydberg wave packets. Background-free detection of the Rydberg dynamics is performed using shaper-generated bichromatic linearly and circularly polarized femtosecond pump-probe pulse sequences. Photoelectron momentum distributions from linearly polarized bichromatic fields feature pronounced time-, energy-, and angle-dependent dynamics, which result from the interference of s-, d-, and g-type photoelectron wave packets from the ionization of the Rydberg np and nf series. Detailed analysis of the highly differential data allows us to extract the dynamics of both Rydberg wave packets separately. The results are experimentally verified by additional pump-probe studies with bichromatic circularly polarized pulse sequences, which exclusively map the dynamics of the Rydberg nf series via g-type photoelectron wave packets.
关键词： Rydberg wave packets,pump-probe spectroscopy,photoelectron imaging,femtosecond lasers,polarization pulse shaping
更新于2025-09-23 15:23:52
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A Study of Two Dimensional Tomography Reconstruction of Temperature and Gas Concentration in a Combustion Field Using TDLAS
摘要： Based on tunable diode laser absorption spectroscopy (TDLAS), two-dimensional (2D) distribution reconstructions of gas concentration and temperature are realized using an algebraic reconstruction technique (ART). The influence of the beam distribution and grid size on combustion field reconstruction is investigated to attain optimal reconstruction results with a limited number of beams. Under limited optical-path numbers, it shows that a better spatial resolution is attainable only when the laser beam paths are vertical and parallel to the symmetry axis of the combustion field. Furthermore, experiments with 16 beam paths using one and two flat flame combustion fields are carried out in different fuel-air equivalence ratios under room temperature. The results are in agreement with the simulation results, and the time resolution is less than 1 s.
关键词： tomographic imaging,diode lasers,temperature,spectroscopy,combustion diagnostics,absorption
更新于2025-09-23 15:23:52