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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) - Contaminant Free End-Capped Acetylene PMC for Sub-Doppler Spectroscopy
摘要： Gas-filled Hollow Core Photonic Cristal Fibres (HCPCF) or Photonic MicroCell (PMC) has proven to offer an outstanding gas-cell for laser metrology and spectroscopy applications. Sub-Doppler spectral features, generated via electromagnetically induced transparency (EIT) or saturated absorption (SA), have been generated in molecular gases despite the weak strength of their optical transitions, and an optical frequency reference with excellent accuracy has been demonstrated. Here, we report on fabrication and spectroscopic (EIT and SA spectroscopy) characterisation of contaminant free acetylene PMC where no He or glue is required. The assembly process of this PMC is based on end-capping both ends of a HCPCF by collapsing a sleeve capillary while the system is still connected to the vacuum preventing any air pollution. The end-cap is then polished and mounted onto FC/APC connectors for easy system integration.
关键词： saturated absorption,Hollow Core Photonic Cristal Fibres,Photonic MicroCell,electromagnetically induced transparency,sub-Doppler spectroscopy
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) - Soliton-Plasma Interactions and Dispersive-Wave Emission Beyond Two-Photon Resonances in Gas-Filled Hollow Capillary Fibres
摘要： Recently we have demonstrated soliton effects at high energy (0.3 mJ) in helium- and neon-filled hollow capillary fibres (HCF) [1]. We observed pulse self-compression to single-cycle durations and the generation of deep (DUV) and vacuum ultraviolet (VUV) radiation at record energy levels for a tunable source. Here, we demonstrate that soliton dynamics in capillary fibres can also be accessed with argon- and krypton-filled HCF, although ionisation effects then start to play a larger role. We also find that the DUV and VUV generation through resonant dispersive-wave (RDW) emission can be achieved at wavelengths considerably shorter than the two-photon resonances in each gas—something surprising, given previous work in gas-filled photonic crystal fibres HC-PCF [2], where soliton-related effects have been previously extensively explored at μJ pulse energy levels [3].
关键词： two-photon resonances,soliton-plasma interactions,dispersive-wave emission,gas-filled hollow capillary fibres
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) - Generation of Broad-Band Circularly Polarised Supercontinuum in Chiral Photonic Crystal Fibre
摘要： Supercontinuum (SC) generation in solid-core photonic crystal fibres (PCFs) is well established and has diverse applications in science and technology [1,2]. In a conventional SC, the polarization state is not maintained over the whole spectrum due to cross-phase modulation and may in addition vary with power. Recently, it has been reported that continuously twisted PCFs exhibit circular birefringence [3,4]. Here we report the first experimental demonstration of a twisted PCF that robustly maintains circular polarization state across the whole spectrum, independent of power.
关键词： Supercontinuum generation,chiral light-matter interactions,photonic crystal fibres,circular polarization
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) - Composite Material Antiresonant Fibre Optical Modulator with >3DB Depth
摘要： Anti-resonant fibres (ARFs) are of significant interest for state of the art photonic technologies. Mode guidance is largely confined to the air core, demonstrating very low optical losses [1]. Furthermore, their internal structure offers a large surface area and is thus ideal as a deposition template for the addition of novel functional materials which would be able to alter their waveguide properties. We have previously demonstrated that the deposition of thin silicon layers onto the inner regions of an ARF results in strong light-matter interaction [2]. In this work, we utilise this interaction to externally control the optical properties of the composite material ARF (CM-ARF). Here, 2D layers of MoS2 were deposited on the inner (cladding) regions of the ARF as shown in Fig. 1(a). MoS2 is a Transition Metal Dichalcogenide (TMDC) 2D material that exhibits many optoelectronic phenomena such as the electro-absorptive effect [3]. Although there are already a number of examples in which TMDCs are incorporated into optical fibre systems to exploit the third order optical nonlinearity of the material to create saturable absorbers [4], this requires large amounts of power to be absorbed by the film, which is usually placed on the end face of a fibre. In contrast, here we show clear modulation at very low power.
关键词： Electro-absorptive effect,MoS2,Composite material ARF,Anti-resonant fibres,Optical modulation
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) - Rare-Earth Doped Phosphate Optical Fibres and Rods for Compact Pulsed Optical Amplification
摘要： In the last decade high energy and high peak power pulsed laser sources have been in a great demand for a variety of applications such as remote sensing (LIDAR, DIAL), range findings, communications systems and material processing. Since the energy of the pulsed laser oscillator is generally much lower than the one required for the applications, a fibre amplifier is commonly used to boost the output power, realizing the so called MOPA (Master Oscillator Power Amplifier) laser architecture. The realization of a fibre amplifier requires an active medium with high optical gain in short length, in order to mitigate nonlinear optical effects. Multicomponent phosphate glasses are recognized to be an ideal host material for the realization of these fibres, as they can be doped with large amounts of rare earth (RE) ions (up to 1021 ions/cm3) without clustering, thus allowing the fabrication of extremely compact active devices with high optical gain (> 5 dB/cm) in short length [1,2]. Moreover, phosphate glasses possess good thermo-mechanical properties, high emission cross-sections, high optical damage threshold and are less susceptible than silica to photodarkening [3,4]. With the aim of realizing short-length amplifiers in the 1 μm and 1.5 μm wavelength range, highly Yb3+ and Yb3+-Er3+-doped custom phosphate glass compositions were designed and fabricated by melt-quenching technique. Suitable cladding compositions were explored. The manufactured glasses were thoroughly investigated. First of all, they were thermo-mechanically characterized, then the glasses underwent optical characterization such as refractive index measurement, FTIR spectroscopy and, for active glass, RE emission spectroscopy resolved in time and frequency. Phosphate fibers and rods were then manufactured by preform drawing using a custom induction heated optical fiber drawing tower, with the preform being obtained by rod-in-tube technique. Preliminary results of optical amplification are presented for a single stage MOPA, both in the 1 μm and 1.5 μm wavelength range.
关键词： compact pulsed optical amplification,Yb3+-Er3+-doped,MOPA,phosphate glass compositions,Yb3+,rare-earth doped phosphate optical fibres
更新于2025-09-11 14:15:04
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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) - Phase Dislocations in the Negative Curvature Hollow Core Fibres
摘要： The negative curvature hollow core fibres (NCHCFs) have attracted recently a great deal of attention because of their potential for many practical applications ranging from optical communications to high power lasers and power delivery. In the NCHCFs light is strongly localized in the air core due to the mode field interaction with the limited portions of the core-cladding boundary. In our work we observed that the light leakage from the hollow core in NCHCFs has features which indicate the formation of phase dislocations and optical vortices in the cladding elements. Here we demonstrate that there are lines in the cladding capillary walls along which the imaginary and real parts of the transverse components of the core mode electric field Ex and Ey are equal to zero and can cross each other (the zero – amplitude lines). The direction of the transverse component of the core mode electric field is uncertain in the vicinity of these lines. Such behaviour of the core mode fields and its polarization indicates the presence of optical vortices in the cladding capillary wall.
关键词： negative curvature hollow core fibres,cladding capillary walls,phase dislocations,optical vortices
更新于2025-09-11 14:15:04
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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) - Non-Invasive Real-Time Characterization of Hollow-Core Photonic Crystal Fibres using Whispering Gallery Mode Spectroscopy
摘要： Single-ring hollow-core photonic crystal fibre (SR-PCF), consisting of a ring of thin-walled glass capillaries surrounding a central hollow core, can offer remarkably low transmission loss [1], and is finding applications in, e.g., wavelength conversion and pulse compression in gases, high-power beam delivery and circular dichroism [2]. As with all microstructured fibres, it is highly desirable to continuously measure the internal structural parameters (e.g. the capillary diameter) during fibre drawing. This would improve the yield of useful fibre lengths, as well as offering better control of structural uniformity along the fibre. Successful tapering of hollow-core fibres also requires a non-destructive method of verifying structural integrity along the taper. We here report for the first time a non-invasive technique for monitoring the capillary diameter in SR-PCF during the draw. The technique relies on excitation of whispering gallery modes (WGMs) in the capillary walls. The frequency spacing between successive WGMs fulfils the well-known condition: (cid:16)(cid:81)(cid:81)1l(cid:14)l(cid:32)cLcap(cid:173)(cid:176)(cid:174)(cid:176)(cid:175)lnl(cid:14)1,m1(cid:14)((cid:81)l(cid:14)1,(cid:16))mnl,m(cid:81)l,m(cid:189)(cid:176)(cid:190)(cid:176)(cid:191)(cid:124)cLncapWGM(cid:81)(1) where c is the speed of light in vacuum, Lcap is the circumference (~2(cid:652)R, where R is the mean radius), l the azimuthal and m the radial mode order, and nl,m is the effective index of the mode. Both approximate analytical solutions to nl,m and full numerical simulations show that, for the SR-PCFs studied, the approximation in Eq.(1) is accurate to within ±0.9% if nWGM is set to 1.484. As illustrated in Fig. 1 (right), the fibre is illuminated transversally by a broadband light source, thereby exciting WGMs inside selected capillaries. By placing a light collection fibre (400 μm core diameter) at a suitable position ~1 cm from the SR-PCF, the WGM spectrum originating from one of the capillaries could be selectively measured. A fast Fourier transform could then be used, together with Eq. (1), to compute the effective capillary diameter 2R in real-time with sub-micron accuracy. The results shown in Fig. 1 (left) were made at a fibre drawing speed of 32.3 m/min and a spectrometer integration time of 70 ms, corresponding to an axial resolution of <4 cm. We also used the technique to measure the diameter of individual capillaries at points along a tapered hollow-core fibre (not shown here).
关键词： Non-invasive,Hollow-core,Real-time,Characterization,Whispering Gallery Mode Spectroscopy,Photonic Crystal Fibres
更新于2025-09-11 14:15:04
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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) - Soliton Self-Compression in Hollow Capillary Fibres
摘要： The creation of shorter and shorter optical pulses at higher and higher energies has been one of the primary aims of laser science and nonlinear optics. At high energies (few mJ), the dominant technique is currently the use of self-phase modulation (SPM) and self-steepening in a gas-filled hollow capillary fibre (HCF) to spectrally broaden pump pulses (typically ~30 fs), followed by chirped mirrors to compensate the phase variation across the spectrum and hence achieve pulse compression [1]. In this way high-energy single-cycle pulses are routinely generated. An alternative route to shorter pulses is soliton self-compression, where the dispersion of the fibre is tuned to be anomalous such that it continuously compensates the phase of the pulse as its spectrum expands. This technique is widely established at low power in solid-core optical fibres and at few-μJ energies in hollow-core photonic-crystal fibres (HC-PCF) [2]. Here we experimentally demonstrate soliton self-compression in conventional gas-filled HCF at much higher energy [3]. We will describe how our technique opens the door to generating 1 fs, 1 TW optical pulses.
关键词： optical pulses,nonlinear optics,hollow capillary fibres,soliton self-compression
更新于2025-09-11 14:15:04
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Polymer Optical Fibres || Fabrication techniques for polymer optical fibres
摘要： A lot of different manufacturing techniques for the production of polymer optical fibres (POF) were developed in the past. Each of these techniques has its own advantages and disadvantages. Thus the choice of a suitable production process depends on the products’ requirements. Some important aspects are: production costs, planned production volume, acceptable attenuation, step-index polymer optical fibres (SI-POF) or graded-index polymer optical fibres (GI-POF). The different manufacturing processes are separated in discontinuous and continuous techniques.
关键词： polymer optical fibres,SI-POF,GI-POF,continuous techniques,manufacturing techniques,discontinuous techniques
更新于2025-09-10 09:29:36
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Guiding light
摘要： Light trapped in hair-thin optical “wires” made of transparent materials such as glass can be piped around tight corners in computer chips, across oceans in telecommunications and back and forth inside a cavity in lasers. By eliminating beam diffraction, and allowing precise control over the beam shape and the chromatic dispersion, optical waveguides make many astonishing things possible.
关键词： dispersion,photonic crystal fibres,optical waveguides,diffraction,telecommunications,lasers
更新于2025-09-10 09:29:36