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Fabrication and characterization of Ge–Ga–Sb–S glass microsphere lasers operating at $\sim 1.9\,{\rm{\mu }}{\rm{m}}$
摘要： We report the fabrication and characterization of germanium gallium antimony sul?de (Ge–Ga–Sb–S or 2S2G, doped with Tm3+ ions) microsphere lasers operating at ～1.9-μm spectral band. Compared to the chalcogenide glasses that are used in previous microsphere lasers, this 2S2G glass has a lower transition temperature and a higher characteristic temperature. This implies that 2S2G microspheres can be fabricated at lower temperatures and the crystallization problem in the sphere-forming process can be alleviated. We show that hundreds of high-quality microspheres (quality factors higher than 105) of various diameters can be produced simultaneously via a droplet sphere-forming method. Microspheres are coupled with silica ?ber tapers for optical characterizations. We demonstrate that Whispering Gallery mode (WGM) patterns in the 1.7–2.0 μm band can be conveniently obtained and that once the pump power exceeds a threshold, single- and multi-mode microsphere lasers can be generated. For a typical microsphere whose diameter is 258.64 μm, we demonstrate its laser threshold is 0.383 mW, the laser wavelength is 1907.38 nm, and the thermal sensitivity of the microsphere laser is 29.56 pm/?C.
关键词： chalcogenides,whispering gallery modes,microspheres laser
更新于2025-11-25 10:30:42
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A Vibrometer Based on Magnetorheological Optical Resonators
摘要： This paper addresses the feasibility of an optical vibrometer that is based on the shift of the optical modes, also known as whispering gallery modes (WGMs), of a magnetorheological optical resonator. The optical resonator that is used in this study is fabricated by mixing polyvinyl chloride plastisol with magnetically polarizable particles. When a permanent magnet that is located nearby the optical resonator is moved, it induces a perturbation of the morphology of the resonator, due to the magnetostrictive effect. This change in the morphology induces a shift in the optical modes of the resonator. The shift of the optical modes can be related to the displacement of the permanent magnet. The proposed sensor concept is based on monitoring the displacement of a tiny magnet that is attached to a moving surface. The optical quality factor of the resonator used in these studies was of the order of 106. The experimental results show a sensitivity of 0.32 pm/μm and a resolution that is less than 300 nm.
关键词： whispering gallery modes,vibrometer,composites,magnetorheological,optical resonator,smart materials
更新于2025-09-23 15:22:29
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Dielectric Microsphere Coupled to a Plasmonic Nanowire: A Self-Assembled Hybrid Optical Antenna
摘要： Hybrid mesoscale structures that can combine dielectric optical resonances with plasmon-polariton waves are of interest in chip-scale nano-optical communication and sensing. This experimental study shows how a fluorescent microsphere coupled to a silver nanowire can act as a remotely excited optical antenna. To realize this architecture, self-assembly methodology is used to couple a fluorescent silica microsphere to a single silver nanowire. By exciting propagating surface plasmon polaritons at one end of the nanowire, remote excitation of the Stokes-shifted whispering gallery modes (WGMs) of the microsphere is achieved. The WGM-mediated fluorescence emission from the system is studied using Fourier plane optical microscopy, and the polar and azimuthal emission angles of the antenna are quantified. Interestingly, the thickness of the silver nanowires is shown to have direct ramification on the angular emission pattern, thus providing a design parameter to tune antenna characteristics. Furthermore, by employing 3D numerical simulations, electric near-field of the gap junction between the microsphere and the nanowire is simulated and is transformed into far field. This work provides a self-assembled optical antenna that combines dielectric optical resonances with propagating plasmons and can be harnessed in hybrid nonlinear nanophotonics and single-molecule remote sensing.
关键词： optical antenna,whispering gallery modes,molecular fluorescence,directional emission,Fourier plane imaging
更新于2025-09-23 15:21:01
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Raman Laser Switching Induced by Cascaded Light Scattering
摘要： It is shown that, in multimode Raman lasers, cascaded light scattering (CLS) not only extends the optical frequency range, but can also modulate the laser dynamics. The origin of this phenomenon lies in the fact that many Raman lasing modes are directly correlated through CLS. The coupled-mode equations only describe single-mode cascaded Raman lasers and are insufficient for describing the multimode case. In this work, additional terms are introduced to account for intermodal interaction and, therefrom the physical mechanism behind the mode-switching phenomenon is revealed. Additionally, mode-switching controlled solely by a single-mode pump in a whispering gallery mode (WGM) silica Raman laser is demonstrated. As the intracavity pump power is increased, laser switching happens between two adjacent WGMs in the same mode family.
关键词： cascaded light scattering,Raman lasers,mode switching,whispering gallery modes
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Si3N4 Waveguide-Coupled Microdisk Resonators with a Quality Factor of 107
摘要： We design and fabricate dispersion-engineered ~830nm-thick Si3N4 waveguide-coupled microdisks. Our resonators show a loaded quality (Q)-factor of ~1×107. We observe optical parametric oscillations in a 345μm-radius microdisk with a threshold pump power of ~50 mW in the waveguide.
关键词： Stoichiometric Si3N4 micordisks,optical parametric oscillations,whispering-gallery modes,high-Q resonators
更新于2025-09-16 10:30:52
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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - The Loss Characteristics of Curved Fiber at Small Radius
摘要： Curved optical fiber sticking onto a round structure has many applications, such as mandrel acoustic sensors and fiber-length scratchable phase modulators. However, the components’ performances are limited by the transmission loss of the wound fibers. In this paper, the bending loss characteristic of curved fiber at small radius is experimentally demonstrated. A modified five-layer slab waveguide theory is used, which indicates that the bend loss has distinct oscillations at small radius. When the bending radius is smaller, the oscillation period changes more observably. In the experiment, single-mode fiber is bended on the outer surface of cylinders with various radius. The experimental result is consistent with theoretical analysis one.
关键词： bend loss,Fiber bending,mode coupling,whispering gallery modes (WGMs)
更新于2025-09-16 10:30:52
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Temperature dependence of whispering gallery modes of quantum dot-doped microbottle resonators
摘要： The temperature dependence of the whispering gallery modes (WGMs) of self-assembled microbottle resonators (MBRs) made of poly (methyl methacrylate) (PMMA) have been studied. The MBRs are doped with fluorescent cadmium selenide quantum dots (QDs). WGMs of MBRs are found to exhibit a blue shift on increasing the temperature over a wide temperature range. It has been observed that the shifts are linear with temperature over a ~10 nm wavelength range studied here. The observed shifts are stable over several cycles and longer exposure times indicating high photo-stability.
关键词： Fluorescence based sensor,Whispering gallery modes,Polymer,Microbottle resonator,Quantum dot
更新于2025-09-16 10:30:52
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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) - On the Possibility of Structural Characterisation of Hollow Core Fibres using Whispering Gallery Modes Excited by Laser and Broadband Light
摘要： Significant progress has been made in recent years in driving down the loss of hollow core fibres (HCFs), such as photonic bandgap fibres (PBGF), antiresonant nodeless fibres (ANF), and nested antiresonant nodeless fibres (NANF) towards that of their conventional solid single mode counterparts. In order to achieve the ultimate performance of HCFs, an accurate control of the dimensions and symmetry of the internal constituent elements is key in both the assembled preforms and drawn canes and fibres. Non-destructive optical methods to monitor and assess the internal features of HCFs over the entire fabrication process are therefore of great interest. Previously, morphology dependent resonances [1] and whispering gallery modes (WGMs) [2], excited by side illumination of the fibre, have been used to enable the precise measurement of cladding diameter variations with an accuracy greater than that of competing interferometric approaches. Motivated by this earlier work we have started studies into the opportunities provided by side illumination of HCF canes and fibres being drawn, and report some of our initial observations, which we hope will ultimately provide useful information on the internal features of HCFs.
关键词： whispering gallery modes,nested antiresonant nodeless fibres,hollow core fibres,photonic bandgap fibres,antiresonant nodeless fibres
更新于2025-09-12 10:27:22
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Folded chaotic whispering-gallery modes in nonconvex, waveguide-coupled planar optical microresonators
摘要： Chaotic whispering-gallery modes have significance both for optical applications and for our understanding of the interplay between wave phenomena and the classical ray limit in the presence of chaotic dynamics and openness. In strongly nonconvex geometries, a theorem by Mather rules out the existence of invariant curves in phase space corresponding to rays circulating in whispering-gallery patterns, so that no corresponding modes of this type are expected. Here, we discuss numerical computations of the electromagnetic fields in planar dielectric cavities that are strongly nonconvex because they are coupled to waveguides. We find a family of special states which retains many features of the chaotic whispering-gallery modes known from convex shapes: An intensity pattern corresponding to near-grazing incidence along extended parts of the boundary, and comparatively high-cavity Q factors. The modes are folded into a figure-eight pattern, so overlap with the boundary is reduced in the region of self-intersection. The modes combine the phenomenology of chaotic whispering-gallery modes with an important technological advantage: The ability to directly attach waveguides without spoiling the Q factor of the folded mode. Using both a boundary-integral method and the finite-difference time-domain technique, we explore the dependence of the phenomenon on wavelength in relation to cavity size, refractive-index contrast to the surrounding medium, and the degree of shape deformation. A feature that distinguishes folded from regular whispering-gallery modes is that a given shape will support high-Q folded chaotic whispering-gallery modes only in certain wavelength windows.
关键词： chaotic whispering-gallery modes,finite-difference time-domain technique,nonconvex geometries,waveguide-coupled planar optical microresonators,boundary-integral method
更新于2025-09-12 10:27:22
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[IEEE 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Sao Paulo, Brazil (2019.10.7-2019.10.9)] 2019 SBFoton International Optics and Photonics Conference (SBFoton IOPC) - Fabrication of cylindrical resonant microcavities using the confinement provided by partially oxidized AlGaAs/GaAs layers
摘要： Two different interfaces for optical con?nement in GaAs resonators (air/GaAs/air, air/GaAs/AlOx) are compared in cylindrical microstructures with 10 μm of diameter. The AlOx is obtained by the lateral oxidation of Al0.9Ga0.1As layers. The spectrum of the resonators is obtained using a tapered ?ber system in the wavelength range between 1470 nm and 1610 nm. The modal separation agrees with simulations. The quality factor for the cylindrical microstructures having air/GaAs/air interface is almost twice the value for the case of AlOx interface. Since it is expected that surface recombination velocity is reduced by a factor of ten for this last case, these structures are expected to be suitable for the development of active resonators.
关键词： whispering gallery modes,quality factor,microdisk,oxidation of AlGaAs
更新于2025-09-11 14:15:04