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David V. Plant - One of the best experts on this subject based on the ideXlab platform.
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thermally controlled coupling of a rolled up Microtube integrated with a waveguide on a silicon electronic photonic integrated circuit
Optics Letters, 2014Co-Authors: Qiuhang Zhong, Zhaobing Tian, Venkat Veerasubramanian, Hadi Tavakoli M Dastjerdi, David V. PlantAbstract:We report on the first experimental demonstration of the thermal control of coupling strength between a rolled-up Microtube and a waveguide on a silicon electronic-photonic integrated circuit. The Microtubes are fabricated by selectively releasing a coherently strained GaAs/InGaAs heterostructure bilayer. The fabricated Microtubes are then integrated with silicon waveguides using an abruptly tapered fiber probe. By tuning the gap between the Microtube and the waveguide using localized heaters, the Microtube–waveguide evanescent coupling is effectively controlled. With heating, the extinction ratio of a Microtube whispering-gallery mode changes over an 18 dB range, while the resonant wavelength remains approximately unchanged. Utilizing this dynamic thermal tuning effect, we realize coupling modulation of the Microtube integrated with the silicon waveguide at 2 kHz with a heater voltage swing of 0–6 V.
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Counterpropagating Whispering-Gallery-Modes of Rolled-up Semiconductor Microtubes
IEEE Photonics Technology Letters, 2013Co-Authors: Qiuhang Zhong, Zhaobing Tian, M. Hadi Tavakoli Dastjerdi, David V. PlantAbstract:We report on the first experimental demonstration of counterpropagating whispering-gallery-modes (WGMs) of rolled-up semiconductor Microtubes. We studied the thermo-optic effect of the Microtube and achieved optical-optical modulation in both propagating and counterpropagating WGMs. We also realized a thermal wavelength-switchable fiber ring laser using the counterpropagating WGMs of the Microtube.
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selective polarization mode excitation in ingaas gaas Microtubes
Optics Letters, 2011Co-Authors: Zhaobing Tian, Venkat Veerasubramanian, Pablo Bianucci, Andrew G Kirk, David V. PlantAbstract:We report on selective polarization mode excitation in InGaAs/GaAs rolled-up Microtubes. The Microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from its host GaAs substrate. An optical fiber abrupt taper is used to pick up the Microtube, while an adiabatically tapered optical fiber is used to couple light into the resonant optical modes of the Microtube. By varying the polarization of the light in the adiabatically tapered fiber both transverse electric and transverse magnetic modes are observed in the Microtube. We also show that the Microtube can be used as a red (0.6 μm) to infrared light (1.5 μm) optical-optical modulator taking advantage of the thermal-optical effect.
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Selective polarization mode excitation in InGaAs/GaAs Microtubes
Optics letters, 2011Co-Authors: Zhaobing Tian, Venkat Veerasubramanian, Pablo Bianucci, Andrew G Kirk, David V. PlantAbstract:We report on selective polarization mode excitation in InGaAs/GaAs rolled-up Microtubes. The Microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from its host GaAs substrate. An optical fiber abrupt taper is used to pick up the Microtube, while an adiabatically tapered optical fiber is used to couple light into the resonant optical modes of the Microtube. By varying the polarization of the light in the adiabatically tapered fiber both transverse electric and transverse magnetic modes are observed in the Microtube. We also show that the Microtube can be used as a red (0.6 μm) to infrared light (1.5 μm) optical-optical modulator taking advantage of the thermal-optical effect.
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self organized inas quantum dot tube lasers and integrated optoelectronics on si
Proceedings of SPIE, 2011Co-Authors: Zetian Mi, David V. Plant, Venkat Veerasubramanian, Zhaobing Tian, Pablo Bianucci, Andrew G Kirk, Feng Li, P J PooleAbstract:We report on the fabrication, characterization and integration of semiconductor Microtube lasers on silicon. These Microtubes are fabricating using standard photolithography techniques on epitaxially grown strained bilayer films, and show remarkable spectral properties attributable to whispering-gallery-mode type optical resonances. We have demonstrated coherent emission coupled to the optical microcavity modes in both GaAs/InGaAs and InGaAsP Microtubes with embedded quantum dots. Furthermore, the GaAs/InGaAs Microtubes have shown room temperature, continuous wave lasing. The Microtubes can be transferred to any foreign substrate without affecting their optical properties. Work is in progress to couple the tubes with integrated silicon-on-insulator waveguides.
Tobias Kipp - One of the best experts on this subject based on the ideXlab platform.
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light confinement and mode splitting in rolled up semiconductor Microtube bottle resonators
Physical Review B, 2012Co-Authors: Ch Strelow, A Stemmann, D Heitmann, C M Schultz, H Rehberg, M Sauer, H Welsch, Ch Heyn, Tobias KippAbstract:We report on the controlled light confinement in Microtube bottle resonators formed by rolled-up strained semiconductor bilayers. We experimentally and theoretically discuss two important properties of this novel kind of microcavities: the axial light confinement and the mode splitting by broken rotational symmetry. Our model bases on the adiabatic separation of circular and axial mode propagation. The circular problem is solved by a simple waveguide model for the specific geometry along the Microtube axis. These solutions act as a quasipotential in a quasi-Schr\"odinger equation for the axial propagation. We experimentally investigated Microtubes with two different axial confinement mechanisms: lobes of varying winding number in the rolling edge and etched rings of a varying wall thickness along the Microtube axis. For the Microtubes with lobes, we observe a very good quantitative agreement with our model and show that axial mode dispersion can even be tailored by the shape of the lobe. For the Microtubes with etched rings, we observe only a qualitative agreement. These Microtubes exhibit a well pronounced mode splitting by broken rotational symmetry that is analyzed by two-dimensional finite-difference time-domain simulations. We observe an oscillating behavior of the amplitude of the splitting as well as of the quality factors of the split modes under variation of the winding number. We show that the splitting is connected to the axial confinement.
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Optical Microtube Ring Resonators
AIP Conference Proceedings, 2007Co-Authors: Tobias Kipp, Ch Strelow, H Welsch, Ch Heyn, Detlef HeitmannAbstract:In this work, we demonstrate that semiconductor Microtubes fabricated by utilizing the self‐rolling mechanism of epitaxially grown strained bilayers can act as optical ring resonators. The mode structure is probed by the photoluminescence of an optically active material, i.e. self‐assembled quantum dots, embedded inside the Microtube wall. We find a spectrum of sharp modes, which is in very good agreement with the result of a theoretical modelling of the Microtube as a closed thin dielectric waveguide. This novel kind of microcavity, in which the optically active material is intrinsically located close to the optical field maximum, is a good candidate for both, new optoelectronic devices and cavity quantum electrodynamic experiments.
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Optical modes in semiconductor Microtube ring resonators.
Physical review letters, 2006Co-Authors: Tobias Kipp, Ch Strelow, H Welsch, Ch Heyn, Detlef HeitmannAbstract:We demonstrate optical modes in $\mathrm{InGaAs}/\mathrm{GaAs}$ Microtubes acting as optical ring resonators. Self-supporting Microtubes were fabricated by optical lithography and wet-etching processes utilizing the self-rolling mechanism of strained bilayers. The optical modes were probed by the photoluminescence of InAs quantum dots embedded in the tube's wall. In this novel Microtube ring resonator we find a spectrum of sharp modes. They are in very good agreement with the theoretical results for a closed thin dielectric waveguide.
D Heitmann - One of the best experts on this subject based on the ideXlab platform.
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light confinement and mode splitting in rolled up semiconductor Microtube bottle resonators
Physical Review B, 2012Co-Authors: Ch Strelow, A Stemmann, D Heitmann, C M Schultz, H Rehberg, M Sauer, H Welsch, Ch Heyn, Tobias KippAbstract:We report on the controlled light confinement in Microtube bottle resonators formed by rolled-up strained semiconductor bilayers. We experimentally and theoretically discuss two important properties of this novel kind of microcavities: the axial light confinement and the mode splitting by broken rotational symmetry. Our model bases on the adiabatic separation of circular and axial mode propagation. The circular problem is solved by a simple waveguide model for the specific geometry along the Microtube axis. These solutions act as a quasipotential in a quasi-Schr\"odinger equation for the axial propagation. We experimentally investigated Microtubes with two different axial confinement mechanisms: lobes of varying winding number in the rolling edge and etched rings of a varying wall thickness along the Microtube axis. For the Microtubes with lobes, we observe a very good quantitative agreement with our model and show that axial mode dispersion can even be tailored by the shape of the lobe. For the Microtubes with etched rings, we observe only a qualitative agreement. These Microtubes exhibit a well pronounced mode splitting by broken rotational symmetry that is analyzed by two-dimensional finite-difference time-domain simulations. We observe an oscillating behavior of the amplitude of the splitting as well as of the quality factors of the split modes under variation of the winding number. We show that the splitting is connected to the axial confinement.
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optical modes excited by evanescent wave coupled pbs nanocrystals in semiconductor Microtube bottle resonators
Nano Letters, 2010Co-Authors: Kay Dietrich, Christian Strelow, Constanze Schliehe, Christian Heyn, A Stemmann, Stephan Schwaiger, Stefan Mendach, Alf Mews, Horst Weller, D HeitmannAbstract:We report on optical modes in rolled-up Microtube resonators that are excited by PbS nanocrystals filled into the Microtube core. Long ranging evanescent fields into the very thin walled Microtubes cause strong emission of the nanocrystals into the resonator modes and a mode shift after a self-removal of the solvent. We present a method to precisely control the number, the energy and the localization of the modes along the Microtube axis.
Charlie Kong - One of the best experts on this subject based on the ideXlab platform.
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critical testing of potential cellular structures within Microtubes in 145 ma volcanic glass from the argo abyssal plain
Chemical Geology, 2017Co-Authors: David Wacey, Kate Eiloart, Martin R Fisk, Martin Saunders, Charlie KongAbstract:Abstract Microtubes within 145 Ma volcanic glass from the Argo Abyssal Plain possess intriguing internal microtextures that under light microscopy resemble biological septa and ovoid microbial cells. These microtextures have previously been used as part of a suite of evidence to support the biogenicity of such Microtubes, and similar textures are beginning to be used in attempts to taxonomically classify Microtubes from both the modern and ancient oceanic crust within an ichnofossil (trace fossil) hierarchy. Here we use high spatial resolution correlative microscopy to characterize the morphology and chemistry of the Argo Microtubes in order to critically assess the origin of these microtextures and increase our understanding of the potential formation mechanisms of Microtubes in volcanic glass. Electron microscopy shows that the Microtubes contain abundant elongated void spaces and when these are reconstructed in three dimensions they closely replicate the morphology and distribution of the previously described ‘septa’. No organic material is associated with the void spaces and so we reinterpret the ‘septa’ as cracks within the clay mineral phase that infills the Microtubes, probably formed during sample collection and/or preparation. One ovoid body also appears to correlate with void space but further data are required to substantiate such an origin. We caution that the study of micro-textures within volcanic glass-hosted Microtubes by optical microscopy alone may be misleading, hence each individual occurrence should be subject to detailed micro- to nano-scale in situ morphological and chemical investigation before being used as a potential biosignature. Several Microtubes do contain elevated levels of carbon, typically found within amorphous carbonate minerals that, along with nontronite clay, have precipitated within the Microtubes. One Microtube contains organic carbon; this is heterogeneously distributed, occurs away from void spaces and is spatially associated with elevated levels of titanium. This organic carbon could originate from in situ biological activity but it could also have been introduced by circulating seawater. Titanium adsorbed onto this organic material may provide a titanium source for the commonly observed titanite mineralization found in ancient volcanic glass-hosted Microtubes within greenstone belts and ophiolites that have experienced low grade metamorphism. Elemental enrichments and depletions in three chemically distinct regions (glass, alteration rim, and tube interior) provide further insights into Microtube formation mechanisms. Alteration rims have sharply defined edges, are about 0.1 μm wide independent of Microtube diameter, and are primarily composed of Si, Al, O ± Ti. The tube interiors are depleted in Si and Al, and most other elements (Ca, Mg, Na, Mn) relative to fresh glass but K and Fe may be enriched. There is no evidence for depletion of elements in the glass immediately exterior to the alteration rim. This favours a mechanism whereby Microtubes grow by increasing in length, rather than increasing in diameter. In this model protons are the major agent of glass alteration and the supply of protons and the kinetics of the formation of the Si-Al alteration rim control the diameter of the Microtubes.
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the nano scale anatomy of a complex carbon lined Microtube in volcanic glass from the 92ma troodos ophiolite cyprus
Chemical Geology, 2014Co-Authors: David Wacey, Martin Saunders, Nicola Mcloughlin, Charlie KongAbstract:Abstract Microtubular alteration textures in the glassy rims of pillow basalts and hyaloclastite may provide evidence of a sub-seafloor biosphere that has persisted since perhaps 3.5 Ga. Reports of organic carbonaceous linings within such Microtubes constitute one of the key lines of evidence for a biogenic origin. However, such linings have until now been studied mainly by low spatial resolution surface analysis techniques, resulting in a limited understanding of their origin. Here we analyze a large, complex Microtube ( Tubulohyalichnus annularis isp.) from the ~ 92 Ma Troodos Ophiolite using focused ion beam milling combined with transmission electron microscopy (FIB-TEM), and focused ion beam serial sectioning combined with scanning electron microscopy (3D-FIB-SEM). These analyses reveal a distinct 50–200 nm thick carbonaceous lining within the Microtube. The lining is almost continuous and closely replicates the outer annulated morphology of the terminal end of the Microtube. A spiral sub-structure previously seen using optical microscopy is also shown to be carbonaceous, comprising sheets that in places span the entire width of the Microtube. Elemental mapping plus electron energy loss spectroscopy (EELS) shows that the carbon is organic and co-occurs with nitrogen. EELS and selected area electron diffraction (SAED) reveal that a clay mineral infills the remainder of the Microtube, and this has a chemistry and structure consistent with the Fe-rich smectite, nontronite. Anti-correlation between carbon and the elements (Al, Ca, Fe, Mg, O, Si) in the infilling clay, plus the morphology of the carbon, show that the carbon lining is a discrete structure that predates clay mineral growth, thereby excluding the later absorption of organics onto the clay. This new data permits the rejection of a hydrothermal or metamorphic fluid derived origin for the carbonaceous linings to T. annularis isp., plus an origin from recent post-obduction groundwater hosted microorganisms. Our favored hypothesis is that the carbonaceous lining and sheet-like sub-structure were formed on the Cretaceous sub-seafloor by microbial activity in the volcanic glass. It is not yet possible however, to ascertain if the organic material comes from the putative microbe(s) that constructed the T. annularis isp. trace fossil, or from microbes that inhabited the pre-existing Microtube. Further analysis of young in-situ oceanic crustal samples using these ultra-high-resolution FIB-TEM and 3D-FIB-SEM techniques may answer this critical outstanding question.
Zhaobing Tian - One of the best experts on this subject based on the ideXlab platform.
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thermally controlled coupling of a rolled up Microtube integrated with a waveguide on a silicon electronic photonic integrated circuit
Optics Letters, 2014Co-Authors: Qiuhang Zhong, Zhaobing Tian, Venkat Veerasubramanian, Hadi Tavakoli M Dastjerdi, David V. PlantAbstract:We report on the first experimental demonstration of the thermal control of coupling strength between a rolled-up Microtube and a waveguide on a silicon electronic-photonic integrated circuit. The Microtubes are fabricated by selectively releasing a coherently strained GaAs/InGaAs heterostructure bilayer. The fabricated Microtubes are then integrated with silicon waveguides using an abruptly tapered fiber probe. By tuning the gap between the Microtube and the waveguide using localized heaters, the Microtube–waveguide evanescent coupling is effectively controlled. With heating, the extinction ratio of a Microtube whispering-gallery mode changes over an 18 dB range, while the resonant wavelength remains approximately unchanged. Utilizing this dynamic thermal tuning effect, we realize coupling modulation of the Microtube integrated with the silicon waveguide at 2 kHz with a heater voltage swing of 0–6 V.
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Counterpropagating Whispering-Gallery-Modes of Rolled-up Semiconductor Microtubes
IEEE Photonics Technology Letters, 2013Co-Authors: Qiuhang Zhong, Zhaobing Tian, M. Hadi Tavakoli Dastjerdi, David V. PlantAbstract:We report on the first experimental demonstration of counterpropagating whispering-gallery-modes (WGMs) of rolled-up semiconductor Microtubes. We studied the thermo-optic effect of the Microtube and achieved optical-optical modulation in both propagating and counterpropagating WGMs. We also realized a thermal wavelength-switchable fiber ring laser using the counterpropagating WGMs of the Microtube.
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selective polarization mode excitation in ingaas gaas Microtubes
Optics Letters, 2011Co-Authors: Zhaobing Tian, Venkat Veerasubramanian, Pablo Bianucci, Andrew G Kirk, David V. PlantAbstract:We report on selective polarization mode excitation in InGaAs/GaAs rolled-up Microtubes. The Microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from its host GaAs substrate. An optical fiber abrupt taper is used to pick up the Microtube, while an adiabatically tapered optical fiber is used to couple light into the resonant optical modes of the Microtube. By varying the polarization of the light in the adiabatically tapered fiber both transverse electric and transverse magnetic modes are observed in the Microtube. We also show that the Microtube can be used as a red (0.6 μm) to infrared light (1.5 μm) optical-optical modulator taking advantage of the thermal-optical effect.
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Selective polarization mode excitation in InGaAs/GaAs Microtubes
Optics letters, 2011Co-Authors: Zhaobing Tian, Venkat Veerasubramanian, Pablo Bianucci, Andrew G Kirk, David V. PlantAbstract:We report on selective polarization mode excitation in InGaAs/GaAs rolled-up Microtubes. The Microtubes are fabricated by selectively releasing a coherently strained InGaAs/GaAs quantum dot layer from its host GaAs substrate. An optical fiber abrupt taper is used to pick up the Microtube, while an adiabatically tapered optical fiber is used to couple light into the resonant optical modes of the Microtube. By varying the polarization of the light in the adiabatically tapered fiber both transverse electric and transverse magnetic modes are observed in the Microtube. We also show that the Microtube can be used as a red (0.6 μm) to infrared light (1.5 μm) optical-optical modulator taking advantage of the thermal-optical effect.
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self organized inas quantum dot tube lasers and integrated optoelectronics on si
Proceedings of SPIE, 2011Co-Authors: Zetian Mi, David V. Plant, Venkat Veerasubramanian, Zhaobing Tian, Pablo Bianucci, Andrew G Kirk, Feng Li, P J PooleAbstract:We report on the fabrication, characterization and integration of semiconductor Microtube lasers on silicon. These Microtubes are fabricating using standard photolithography techniques on epitaxially grown strained bilayer films, and show remarkable spectral properties attributable to whispering-gallery-mode type optical resonances. We have demonstrated coherent emission coupled to the optical microcavity modes in both GaAs/InGaAs and InGaAsP Microtubes with embedded quantum dots. Furthermore, the GaAs/InGaAs Microtubes have shown room temperature, continuous wave lasing. The Microtubes can be transferred to any foreign substrate without affecting their optical properties. Work is in progress to couple the tubes with integrated silicon-on-insulator waveguides.