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[IEEE 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Paris (2018.7.8-2018.7.13)] 2018 Conference on Precision Electromagnetic Measurements (CPEM 2018) - Two-Branch Fiber Links for International Clock Networks
摘要： Comparisons of clocks through fiber links at the continental scale have become a reality in Europe, opening the way to the realization of a clock network. We will show that we can improve the reliability of the frequency comparison by combining several dissemination techniques. We will report on the implemention of a two-branch fiber link, as part of a wider concatenation of links between NMIs in Europe. This is a key step towards a new definition of the SI second based on optical frequency standards and opens novel opportunities for stringent tests of fundamental physics.
关键词： ultrastable lasers,optical frequency dissemination,phase-lock loop,fiber links
更新于2025-09-23 15:23:52
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single crystals
摘要： 3at.%Tm3+:Ca1?xGdxF2+x (x = 0, 0.005, 0.01, 0.02) single crystals were grown by the vertical Bridgman method, where Gd3+ ions play the role of manipulating ions for local structure to form a disordered lattice site. Spectral properties of these crystals were investigated. Compared to 3at.%Tm3+:CaF2, the spectral parameters of 3at.%Tm3+:Ca1?xGdxF2+x were drastically enhanced in a large scale. LD pumped lasers have been demonstrated in the crystals for the first time. For CW operation, the slope efficiency up to 49.7% was achieved with output power of 1.927 W at 1970 nm. With a birefringent quartz plate, wavelength-tunable laser operation with a tuning range of more than 176 nm was realized.
关键词： Spectral properties,Single crystals,Gd3+ ions,LD pumped lasers
更新于2025-09-23 15:23:52
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Near-Infrared Lasing at 1 μm from a Dilute-Nitride-Based Multishell Nanowire
摘要： A coherent photon source emitting at near-infrared (NIR) wavelengths is at the heart of a wide variety of applications ranging from telecommunications, optical gas sensing to biological imaging, and metrology. NIR-emitting semiconductor nanowires (NWs), acting both as a miniaturized optical resonator and as a photonic gain medium, are among the best-suited nanomaterials to achieve such goals. In this study, we demonstrate the NIR lasing at 1 μm from GaAs/GaNAs/GaAs core/shell/cap dilute nitride nanowires with only 2.5 % of nitrogen. The achieved lasing is characterized by an 'S'-shape pump-power dependence and narrowing of the emission line-width. Through examining the lasing performance from a set of different single NWs, a threshold gain, g_th, of 4100 – 4800 cm^{-1}, was derived, with a spontaneous emission coupling factor, β, up to 0.8, which demonstrate the great potential of such nanophotonic material. The lasing mode was found to arise from the fundamental HE11a mode of the Fabry-Perot cavity from a single NW, exhibiting optical polarization along the NW axis. Based on temperature dependence of the lasing emission, a high characteristic temperature, T_0, of 160(±10) K is estimated. Our results, therefore, demonstrate a promising alternative route to achieve room-temperature NIR NW lasers thanks to the excellent alloy tunability and superior optical performance of such dilute nitride materials.
关键词： dilute nitride,GaAs/GaNAs/GaAs,core/shell/cap structure,Nanowire lasers
更新于2025-09-23 15:23:52
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Optimization of a supercontinuum source based on tapered ordinary fibers
摘要： In this paper the generation of visible spectrum via optimized supercontinuum generation (SCG) in tapered ordinary fibers by ultrashort laser pulses is presented. The tunability of the visible part of the spectra is achieved by changing the pump pulse duration during operation. The optimization of the SCG is carried out by the investigation of the taper geometry with the emphasis on the downtapering section length. Its increase is found to be correlated to higher intensity in the visible part of the spectra. This is further supported by the results on spectra evolution before it enters the taper waist where an important transfer of the pump power to the shorter wavelengths is found.
关键词： fiber lasers,ytterbium-doped fiber amplifiers,supercontinuum generation
更新于2025-09-23 15:23:52
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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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High-gain optical injection locking amplifier in phase-coherent optical frequency transmission
摘要： Optical amplification, which is necessary for extending the distance of optical frequency transfer, has significant impact on the transmission performance. In this paper, we propose a high gain optical injection locking amplifier (OILA) with low phase noise based on optical injection phase-locked loop for the phase-coherent optical frequency transmission. The high gain OILA can provide more than 75 dB gain and ensure that the input carrier frequency fractional stability can reach 8.2 × 10-20 at an averaging time of over 100 s. We then transfer a commercial narrow-linewidth laser over 220 km fiber link with only one amplification step placed at the remote end. After eliminating the noise induced in fiber link, the fractional frequency instability of transferred frequency can reach 9.0 × 10?16 at 1 s and 7.1 × 10?20 at 20000 s.
关键词： Laser injection-locked,Optical standards and testing.,Metrology,Diode lasers
更新于2025-09-23 15:22:29
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2.01～ 2.42 μm all-fiber femtosecond Raman soliton generation in a heavily germanium doped fiber
摘要： We demonstrated that an all-fiber system generates high-performance mid-infrared Raman solitons in a heavily germanium doped fiber (HGDF). A 10 m-long HGDF with a 12 μm core diameter and 64 mol.% GeO2 dopant is designed and pumped by a home-made 1.96 μm femtosecond fiber laser in the strong anomalous dispersion region. Stable and single-color Raman solitons are therefore obtained with a continuous wavelength tunability from 2.01 to 2.42 μm. The pulse duration of the mid-infrared Raman solitons can be as short as ~220 fs. The efficiency of energy transfer to a Raman soliton is about 32.5%, while the maximum average power, peak power and pulse energy are up to 27 mW, 3.6 kW and ~1 nJ, respectively. Different from previous multi-color Raman or supercontinuum-like generation from HGDFs pumped in the near-zero or normal dispersion regime, such pure mid-infrared Raman solitons exhibit excellent stability with a radio-frequency signal-to-noise ratio of ~60 dB. This is, to the best of our knowledge, the first demonstration of >2.4 μm stable Raman solitons in an all-fiber system. This work may pave a path towards compact and high-performance mid-infrared femtosecond fiber laser sources.
关键词： soliton self-frequency shift,Ultrafast fiber lasers,heavily germanium doped fiber,mid-infrared
更新于2025-09-23 15:22:29
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WaterSpy: A High Sensitivity, Portable Photonic Device for Pervasive Water Quality Analysis
摘要： In this paper, we present WaterSpy, a project developing an innovative, compact, cost-effective photonic device for pervasive water quality sensing, operating in the mid-IR spectral range. The approach combines the use of advanced Quantum Cascade Lasers (QCLs) employing the Vernier effect, used as light source, with novel, fibre-coupled, fast and sensitive Higher Operation Temperature (HOT) photodetectors, used as sensors. These will be complemented by optimised laser driving and detector electronics, laser modulation and signal conditioning technologies. The paper presents the WaterSpy concept, the requirements elicited, the preliminary architecture design of the device, the use cases in which it will be validated, while highlighting the innovative technologies that contribute to the advancement of the current state of the art.
关键词： Quantum Cascade Lasers,photonics,water quality monitoring,photodetectors
更新于2025-09-23 15:22:29
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Monodisperse Six-Armed Starbursts based on Truxene-Cored Multibranched Oligofluorenes: Design, Synthesis, and Stabilized Lasing Characteristics
摘要： A series of monodisperse six-armed conjugated starbursts (Tr1F, Tr2F and Tr3F) containing a truxene core and multibranched oligofluorene bridges capped with diphenylamine (DPA) units has been designed, synthesized, and investigated as robust gain media for organic semiconductor lasers (OSLs). The influence of electron-rich DPA end-groups on their optoelectronic characteristics has been discussed at length. DPA cappers effectively raise HOMO levels of the starbursts, thus enhancing the hole injection and transport ability. Solution-processed electroluminescence devices based on the resulting six-armed starbursts exhibited efficient deep-blue electroluminescence with clear reduced turn-on voltages (3.2~3.5 V). Moreover, the resulting six-armed molecules showed stabilized electroluminescence and amplified spontaneous emission with low thresholds (27.4~63.9 nJ pulse-1), high net gain coefficients (80.1~101.3 cm-1), and small optical loss (2.6~4.4 cm-1). Distributed feedback OSLs made from Tr3F exhibited low lasing threshold of 0.31 kW/cm2 (at 465 nm). The results suggest that the construction of truxene-centered six-armed conjugated starbursts with the incorporation of DPA units can effectively enhance EL properties by precisely regulating the HOMO energy levels, and further optimizing their optical gain properties.
关键词： Organic gain media,Organic light-emitting diodes (OLEDs),Conjugated starburst molecules,Organic semiconductor lasers (OSLs),HOMO levels
更新于2025-09-23 15:22:29
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Highly Controllable Lasing Actions in Lead Halide Perovskite-Si <sub/>3</sub> N <sub/>4</sub> Hybrid Micro-Resonators
摘要： Lead halide perovskite (MAPbX3) nanosheets are promising materials for optoelectronic devices. However, as the as-grown perovskite nanosheets typically have random sizes, positions, and alignments, their device performances are hard to be controlled and repeated, significantly hindering the practical applications in nanophotonics. Herein, a novel approach to realize highly controllable lasing actions in MAPbX3 nanosheets is demonstrated. By hybridizing the perovskite with an Si3N4 wafer, it is shown that the cavity shape and the internal lasing actions are precisely controllable via the patterns in Si3N4 wafer, which is pre-defined with mature CMOS technique and will not spoil the exceptional gain of perovskite nanosheet. Consequently, whispering gallery mode (WGM) micro-lasers with well-controlled mode numbers, mode spacing, repeatability, directionalities, and even internal angular momentum are experimentally realized. In addition, by constructing coupled micro-structures, the proximity effects between WGM lasers are also explored. This research provides a substrate-control mechanism to precisely define and control MAPbX3 perovskite micro-lasers.
关键词： perovskite lasers,substrate control,micro-cavities
更新于2025-09-23 15:22:29