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Low threshold, dual-wavelength, mid-infrared optical parametric oscillator
摘要： In this letter, we demonstrated a dual-wavelength (DW) mid-infrared optical parametric oscillator (OPO) that was pumped by two independent fiber lasers fixed at 1018 nm and 1080 nm, and realized phase-matched signal beam coupling by tuning grating period of PPLN. Based on signal beam coupling, two interesting phenomena were observed for the first time. One is that the OPO threshold for 1018 nm and 1080 nm pump beams could be drastically lowered from 15.4 W to 266 mW and from 13.5 W to 1.38 W separately. The other is that the total idler power obtained when the OPO was simultaneously pumped by two fiber lasers was higher than sum of idler power obtained when the OPO was independently pumped by two fiber lasers, revealing obvious parametric gain enhancement. It also indicated that the two independent OPO processes became coherent when two signal beams were coupled. The results exhibit great potential in practical applications such as frequency down-conversion of some special near-infrared laser sources such as pulsed single-frequency sources, spectrum high-speed swept sources, and ultra-short pulse sources with low duty cycle.
关键词： fiber lasers,Infrared lasers,nonlinear,nonlinear crystals
更新于2025-09-23 15:22:29
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Advances in Mid-Infrared Spectroscopy-Based Sensing Techniques for Exhaled Breath Diagnostics
摘要： Human exhaled breath consists of more than 3000 volatile organic compounds, many of which are relevant biomarkers for various diseases. Although gas chromatography has been the gold standard for volatile organic compound (VOC) detection in exhaled breath, recent developments in mid-infrared (MIR) laser spectroscopy have led to the promise of compact point-of-care (POC) optical instruments enabling even single breath diagnostics. In this review, we discuss the evolution of MIR sensing technologies with a special focus on photoacoustic spectroscopy, and its application in exhaled breath biomarker detection. While mid-infrared point-of-care instrumentation promises high sensitivity and inherent molecular selectivity, the lack of standardization of the various techniques has to be overcome for translating these techniques into more widespread real-time clinical use.
关键词： point-of-care (POC),infrared lasers,MIR,photoacoustic spectroscopy,biomarkers,exhaled breath analysis,non-invasive diagnostics,QCL,quantum cascade lasers,mid-infrared
更新于2025-09-23 15:21:01
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Enhanced 2???μm Mida??Infrared Laser Output from Tm <sup>3+</sup> a??Activated Glass Ceramic Microcavities
摘要： Transparent glass ceramics (GCs) consisting of an homogeneous glass phase and a well-dispersed crystal phase are considered as ideal optical gain materials potentially applied in optoelectronic devices due to the combination of facile processability of glass and the intense crystal ?eld of nanocrystals. Here, a heat-induced nanocrystal-in-glass method is employed to integrate the active ions Tm3+ into Bi2Te4O11 nanocrystals with an intense crystal ?eld to realize an enhanced microlaser output. This strategy endows the e?cient tellurate GC microcavity laser operating at ≈2 μm. Compared with the laser properties of as-prepared glass microcavities, the pump threshold (260 μW) is as low as less than a quarter and the slope e?ciency (0.0296%) is 5.5 times higher. Furthermore, by carefully engineering the heat treatment temperature and duration, the crystal size and distribution can be precisely controlled. Thus, the Rayleigh scattering loss that is detrimental to quality (Q) factor is e?ectively suppressed and the GC microcavities with high Q factors up to 105 are successfully obtained. This work provides useful insight on the development of optical functional materials and expands the practical applications of GC microcavities in various optoelectronic ?elds.
关键词： mid-infrared lasers,glass-ceramic microspheres,microcavities,whispering gallery mode
更新于2025-09-23 15:21:01
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Promotion impact of thermal oxidation etching to saturable absorption performance of g-C3N4
摘要： A facile thermal modification method based on thermal oxidation etching was successfully developed as an effective way of improving the photoelectric properties of graphite carbon nitride (g-C3N4), and the as-prepared modified g-C3N4 was employed as the saturable absorber (SA) for a passively Q-switched Nd:LLF laser at 1.06 μm to improve the laser performance. Under the incident pump power of 7.68 W, a pulsed laser output with 110 ns pulse width at 95.5 kHz pulse repetition rate was achieved, which was the narrowest among the g-C3N4 materials used as SAs around 1 μm.
关键词： Q-switched laser,2D materials,g-C3N4 saturable absorber,Infrared lasers
更新于2025-09-19 17:15:36
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All-Fiber Bidirectional Mode-Locked Ultrafast Fiber Laser at 2? <i>μ</i> m
摘要： In this paper, we demonstrated an all-?ber bidirectional ultrafast thulium-doped ?ber laser at 2 μm with a single-wall carbon nanotube presented as saturable absorber. We successfully obtained bidirectional mode-locking operations with pulse repetition frequency adjustable from 35 to 122 MHz by shortening the cavity length. Meanwhile, with the reduction of the intracavity dispersion, the number of Kelly sidebands was signi?cantly decreased and the output energy was more concentrated on the soliton pulse. Besides, by manipulating the pump power and polarization controller, the two results of bidirectional mode-locked pulses with the same repetition frequency and differential repetition frequency were observed. We found that the repetition rate difference between the clockwise and counterclockwise pulse trains was adjustable by changing the pump power or controlling the intracavity polarization. When the pulse repetition frequency was 35 MHz and 122 MHz, the adjustment range of repetition rate difference was 764–922 Hz and 540–2000 Hz, respectively. It is believed that this novel laser source can support free-running dual optical comb spectroscopy to detect important air gases like H2O or CO2 in the future.
关键词： infrared and far-infrared lasers,thulium-doped ?ber,?ber optics and oscillators,Ultrafast lasers
更新于2025-09-16 10:30:52
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Bi-Activated Glasses and their Potential Covering Spectral Region as Active Media for Tunable near Infrared Lasers
摘要： To obtain the near infrared luminescence Bi-activated phosphate-aluminum-natrium glasses were synthesized and treated under reduction conditions. The reduction conditions were achieved by different methods: treatment in graphite atmosphere, hydrogen atmosphere, and X-ray irradiation. The spectral-luminescent properties of glass samples were measured and analyzed. Bi-activated phosphate-aluminum-natrium glasses after reduction treatment have shown wide near infrared luminescence with two peaks at the telecommunication windows region. The nature of the luminescent centers in Bi-activated phosphate-aluminum-natrium glasses are discussed. The spectral-luminescent properties of synthesized glasses were studied at the context of Bi-activated glass as the active media for tunable near infrared lasers operating in 1050-1500 nm region. The demonstrated properties of Bi-activated phosphate-aluminum-natrium glass are promising to fill the gap in near infrared lasers operating range.
关键词： Tunable infrared lasers,near infrared luminescence,Bi-doped glasses,spectral-luminescent properties of bismuth in glass matrix
更新于2025-09-16 10:30:52
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A passively Q-switching of diode-pumped 2.08-μm Ho:CaF2 laser
摘要： In this paper we demonstrate a continuous wave and passively Q-switched Ho:CaF2 laser pumped by a laser diode at 1.94 μm. In the continuous wave regime, the Ho:CaF2 laser produced 4.2 W output power at 2085.2 nm, corresponding to the slope efficiency of 48.4% with respect to the absorbed pump power. With Cr2+:ZnS saturable absorber, the maximum average output power of 3.6 W at 2084.1 nm, minimum pulse width of 92 ns and repletion rate of 5.88 kHz were achieved with a slope efficiency of 42.2%. Furthermore, the beam quality factors of passively Q-switched diode-pumped Ho:CaF2 laser were estimated to be about 1.3 in both vertical and horizontal directions.
关键词： Diode-pumped,Passive Q-switched,Ho:CaF2,Infrared lasers
更新于2025-09-12 10:27:22
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Infrared laser based contacting of bar-wound windings in the field of electric drives production
摘要： Driven by electric mobility innovative winding methods increasing the copper fill ratio and thus the power density of electrical drives gain in importance. Compared to conventional windings, bar-wound windings based on rectangular cross sections besides optimized copper fill ratios also offer advantages in terms of automated production. Because of the high number of joints necessary for the manufacturing of the winding, contacting efforts increase significantly wherefore the process of laser welding, due to its short process times and high reproducibility shows potentials to realize the process step. This paper examines the most important interactions within the process of laser welding of insulated copper wires with rectangular cross sections in the context of electric drives production. Besides workpiece specific factors, the focus is set on process parameters, beam guidance strategies and specific quality requirements. For this purpose, a parameter study based on design of experiments is executed in which suitable measuring technologies are used to quantify the properties of the samples.
关键词： hairpin windings,infrared lasers,electrical contacts,insulated copper conductors,laser beam welding
更新于2025-09-12 10:27:22
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Low-cost multimode diode-pumped Tm:YAG and Tm:LuAG lasers
摘要： We report a continuous-wave operation of Tm:YAG and Tm:LuAG lasers pumped with a low-cost, multimode AlGaAs laser diode. First, the lifetime and the absorbance behavior of 5 mm, 6% Tm 3+ -doped YAG and LuAG crystals were thoroughly investigated. A low-cost multimode 3W laser diode at 781 nm was then used as a pump source for the Tm 3+ -doped laser systems. Using three different output couplers, up to 636 mW of output power was obtained from Tm:YAG laser, with a slope efficiency of 29% at 2017 nm. The maximum output power was 637 mW in the Tm:LuAG laser, with a slope efficiency of 28% at 2023 nm. The lasing performances showed a decreasing slope efficiency with an increasing level of output coupling, which leads to a high upconversion. Furthermore, using a birefringent filter in the resonators, the laser outputs were tuned from 1942 to 2086 nm in the Tm:YAG resonator and from 1931 to 2107 nm in the Tm:LuAG case.
关键词： diode-pumped lasers,infrared lasers,Tm:LuAG laser,Tm:YAG laser,tunable lasers,solid-state lasers,Lasers
更新于2025-09-11 14:15:04
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Quasi-all-fiber structure CW mid-infrared laser emission from gas-filled hollow-core silica fibers
摘要： A quasi-all-?ber structure CW mid-infrared ?ber lasers based on gas-?lled hollow-core ?bers (HCFs) is ?rstly reported here. Through a thermally tapered single-mode ?ber, the CW tunable 1.5 μm ?ber pump light is coupled into an acetylene-?lled anti-resonance HCFs, and the coupling point is sealed with epoxy glue to ensure the stability and gas tightness, then the HCFs is ?lled with acetylene gas by a specially designed small gas cell, just like an end cap. When the pump is precisely tuned to the resonance with the absorption lines of acetylene, CW mid-infrared emission around 3.1–3.2 μm is generated at room temperature with maximum power of ~180 mW and slope e?ciency of ~14%. The laser threshold is also discussed as function of acetylene pressure. This work opens new opportunities for all-?ber mid-infrared lasers of new wavelengths those unavailable for traditional rare-earth-doped ?bers.
关键词： Molecular gas lasers,Infrared and far-infrared lasers,Fiber lasers,Photonic crystal ?bers
更新于2025-09-11 14:15:04