The Experts below are selected from a list of 5034 Experts worldwide ranked by ideXlab platform
Kerry J Vahala - One of the best experts on this subject based on the ideXlab platform.
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demonstration of ultra high q small mode volume Toroid microcavities on a chip
Applied Physics Letters, 2004Co-Authors: Tobias J Kippenberg, S M Spillane, Kerry J VahalaAbstract:Optical microcavities confine light spatially and temporally and find application in a wide range of fundamental and applied studies. In many areas, the microcavity figure of merit is not only determined by photon lifetime (or the equivalent quality-factor, Q), but also by simultaneous achievement of small mode volume (V). Here we demonstrate ultra-high Q-factor small mode volume Toroid microcavities on-a-chip, which exhibit a Q/V factor of more than 10^6 (lambda/n)^–3. These values are the highest reported to date for any chip-based microcavity. A corresponding Purcell factor in excess of 200,000 and a cavity finesse of > 2.8×10^6 is achieved, demonstrating that Toroid microcavities are promising candidates for studies of the Purcell effect, cavity QED or biochemical sensing.
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demonstration of ultra high q small mode volume Toroid microcavities on a chip
arXiv: Optics, 2004Co-Authors: Tobias J Kippenberg, S M Spillane, Kerry J VahalaAbstract:Optical microcavities confine light spatially and temporally and find application in a wide range of fundamental and applied studies. In many areas, the microcavity figure of merit is not only determined by photon lifetime (or the equivalent quality-factor, Q), but also by simultaneous achievement of small mode volume V . Here we demonstrate ultra-high Q-factor small mode volume Toroid microcavities on-a-chip, which exhibit a Q/V factor of more than $10^{6}(\lambda/n)^{-3}$. These values are the highest reported to date for any chip-based microcavity. A corresponding Purcell factor in excess of 200 000 and a cavity finesse of $2.8\times10^{6}$ is achieved, demonstrating that Toroid microcavities are promising candidates for studies of the Purcell effect, cavity QED or biochemical sensing
Nicholas V Hud - One of the best experts on this subject based on the ideXlab platform.
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evidence that both kinetic and thermodynamic factors govern dna Toroid dimensions effects of magnesium ii on dna condensation by hexammine cobalt iii
Biochemistry, 2004Co-Authors: Christine C Conwell, Nicholas V HudAbstract:Millimolar concentrations of divalent cations are shown to affect the size of Toroids formed when DNA is condensed by multivalent cations. The origins of this effect were explored by varying the order in which MgCl(2) was added to a series of DNA condensation reactions with hexammine cobalt chloride. The interplay between Mg(II), temperature, and absolute cation concentration on DNA condensation was also investigated. These studies reveal that DNA condensation is extremely sensitive to whether Mg(II) is associated with DNA prior to condensation or Mg(II) is added concurrently with hexammine cobalt(III) at the time of condensation. It was also found that, in the presence of Mg(II), temperature and dilution can have opposite effects on the degree of DNA condensation. A systematic comparison of DNA condensates observed in this study clearly illustrates that, under our low-salt conditions, Toroid size is determined by the kinetics of Toroid nucleation and growth. However, when Mg(II) is present during condensation, Toroid size can also be limited by a thermodynamic parameter (e.g., undercharging). The path dependence of DNA condensation presented here illustrates that regardless of which particular factors limit Toroid growth, Toroids formed under the various conditions of this study are largely nonequilibrium structures.
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controlling the size of nanoscale Toroidal dna condensates with static curvature and ionic strength
Proceedings of the National Academy of Sciences of the United States of America, 2003Co-Authors: Christine C Conwell, Igor D Vilfan, Nicholas V HudAbstract:The process of DNA condensation into nanometer-scale particles has direct relevance to several fields, including cell biology, virology, and gene delivery for therapeutic purposes. DNA condensation has also attracted the attention of polymer physicists, as the collapse of DNA molecules from solution into well defined particles represents an exquisite example of a polymer phase transition. Here we present a quantitative study of DNA Toroids formed by condensation of 3 kb DNA with hexammine cobalt (III). The presence or absence of static loops within this DNA molecule demonstrates the effect of nucleation loop size on Toroid dimensions and that nucleation is principally decoupled from Toroid growth. A comparison of DNA condensates formed at low ionic strength with those formed in the presence of additional salts (NaCl or MgCl2) shows that Toroid thickness is a salt-dependant phenomenon. Together, these results have allowed the development of models for DNA Toroid formation in which the size of the nucleation loop directly influences the diameter of the fully formed Toroid, whereas solution conditions govern Toroid thickness. The data presented illustrate the potential that exists for controlling DNA Toroid dimensions. Furthermore, this study provides a set of data that should prove useful as a test for theoretical models of DNA condensation.
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cryoelectron microscopy of lambda phage dna condensates in vitreous ice the fine structure of dna Toroids
Proceedings of the National Academy of Sciences of the United States of America, 2001Co-Authors: Nicholas V Hud, Kenneth H DowningAbstract:Abstract DNA Toroids produced by the condensation of λ phage DNA with hexammine cobalt (III) have been investigated by cryoelectron microscopy. Image resolution obtained by this technique has allowed unprecedented views of DNA packing within Toroidal condensates. Toroids oriented coplanar with the microscope image plane exhibit circular fringes with a repeat spacing of 2.4 nm. For some Toroids these fringes are observed around almost the entire circumference of the Toroid. However, for most Toroids well-defined fringes are limited to less than one-third of the total Toroid circumference. Some Toroids oriented perpendicular to the image plane reveal DNA polymers organized in a hexagonal close-packed lattice; however, for other Toroids alternative packing arrangements are observed. To aid interpretation of electron micrographs, three-dimensional model Toroids were generated with perfect hexagonal DNA packing throughout, as well as more physically realistic models that contain crossover points between DNA loops. Simulated transmission electron microscopy images of these model Toroids in different orientations faithfully reproduce most features observed in cryoelectron micrographs of actual Toroids.
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a constant radius of curvature model for the organization of dna in Toroidal condensates
Proceedings of the National Academy of Sciences of the United States of America, 1995Co-Authors: Nicholas V Hud, K H Downing, Rod BalhornAbstract:Abstract Toroidal DNA condensates have received considerable attention for their possible relationship to the packaging of DNA in viruses and in general as a model of ordered DNA condensation. A spool-like model has primarily been supported for DNA organization within Toroids. However, our observations suggest that the actual organization may be considerably different. We present an alternate model in which DNA for a given Toroid is organized within a series of equally sized contiguous loops that precess about the Toroid axis. A related model for the Toroid formation process is also presented. This kinetic model predicts a distribution of Toroid sizes for DNA condensed from solution that is in good agreement with experimental data.
Tobias J Kippenberg - One of the best experts on this subject based on the ideXlab platform.
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demonstration of ultra high q small mode volume Toroid microcavities on a chip
Applied Physics Letters, 2004Co-Authors: Tobias J Kippenberg, S M Spillane, Kerry J VahalaAbstract:Optical microcavities confine light spatially and temporally and find application in a wide range of fundamental and applied studies. In many areas, the microcavity figure of merit is not only determined by photon lifetime (or the equivalent quality-factor, Q), but also by simultaneous achievement of small mode volume (V). Here we demonstrate ultra-high Q-factor small mode volume Toroid microcavities on-a-chip, which exhibit a Q/V factor of more than 10^6 (lambda/n)^–3. These values are the highest reported to date for any chip-based microcavity. A corresponding Purcell factor in excess of 200,000 and a cavity finesse of > 2.8×10^6 is achieved, demonstrating that Toroid microcavities are promising candidates for studies of the Purcell effect, cavity QED or biochemical sensing.
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demonstration of ultra high q small mode volume Toroid microcavities on a chip
arXiv: Optics, 2004Co-Authors: Tobias J Kippenberg, S M Spillane, Kerry J VahalaAbstract:Optical microcavities confine light spatially and temporally and find application in a wide range of fundamental and applied studies. In many areas, the microcavity figure of merit is not only determined by photon lifetime (or the equivalent quality-factor, Q), but also by simultaneous achievement of small mode volume V . Here we demonstrate ultra-high Q-factor small mode volume Toroid microcavities on-a-chip, which exhibit a Q/V factor of more than $10^{6}(\lambda/n)^{-3}$. These values are the highest reported to date for any chip-based microcavity. A corresponding Purcell factor in excess of 200 000 and a cavity finesse of $2.8\times10^{6}$ is achieved, demonstrating that Toroid microcavities are promising candidates for studies of the Purcell effect, cavity QED or biochemical sensing
Takasumi Tanabe - One of the best experts on this subject based on the ideXlab platform.
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kerr induced controllable adiabatic frequency conversion in an ultrahigh q silica Toroid microcavity
Optics Letters, 2016Co-Authors: Wataru Yoshiki, Yoshihiro Honda, Misako Kobayashi, Tomohiro Tetsumoto, Takasumi TanabeAbstract:In this Letter, we report, based on our knowledge, the first demonstration of Kerr-induced adiabatic frequency conversion in a silica Toroid microcavity. Taking advantage of the instantaneous response of the Kerr effect, we achieved adiabatic frequency conversion with a controllable amount of frequency shift and time width. In addition, thanks to the combination of the Kerr effect and the ultrahigh Q (>107) of the silica Toroid microcavity, we also observed multiple frequency conversion within a photon lifetime. Furthermore, use of the Kerr effect allowed us to investigate the influence of the relative phase between the original and converted light.
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all optical switching using kerr effect in a silica Toroid microcavity
arXiv: Optics, 2014Co-Authors: Wataru Yoshiki, Takasumi TanabeAbstract:We demonstrate experimentally an all-optical switching operation using the Kerr effect in a silica Toroid microcavity. Thanks to the small mode volume and high quality factor of the silica Toroid microcavity, we achieved on-chip optical Kerr switching with an input power of 2 mW. This value is the smallest among all previously reported on-chip optical Kerr switches. We also show that this value can be reduced to a few tens of uW by employing a mode with a Q factor of >2x10^7.
S M Spillane - One of the best experts on this subject based on the ideXlab platform.
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demonstration of ultra high q small mode volume Toroid microcavities on a chip
Applied Physics Letters, 2004Co-Authors: Tobias J Kippenberg, S M Spillane, Kerry J VahalaAbstract:Optical microcavities confine light spatially and temporally and find application in a wide range of fundamental and applied studies. In many areas, the microcavity figure of merit is not only determined by photon lifetime (or the equivalent quality-factor, Q), but also by simultaneous achievement of small mode volume (V). Here we demonstrate ultra-high Q-factor small mode volume Toroid microcavities on-a-chip, which exhibit a Q/V factor of more than 10^6 (lambda/n)^–3. These values are the highest reported to date for any chip-based microcavity. A corresponding Purcell factor in excess of 200,000 and a cavity finesse of > 2.8×10^6 is achieved, demonstrating that Toroid microcavities are promising candidates for studies of the Purcell effect, cavity QED or biochemical sensing.
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demonstration of ultra high q small mode volume Toroid microcavities on a chip
arXiv: Optics, 2004Co-Authors: Tobias J Kippenberg, S M Spillane, Kerry J VahalaAbstract:Optical microcavities confine light spatially and temporally and find application in a wide range of fundamental and applied studies. In many areas, the microcavity figure of merit is not only determined by photon lifetime (or the equivalent quality-factor, Q), but also by simultaneous achievement of small mode volume V . Here we demonstrate ultra-high Q-factor small mode volume Toroid microcavities on-a-chip, which exhibit a Q/V factor of more than $10^{6}(\lambda/n)^{-3}$. These values are the highest reported to date for any chip-based microcavity. A corresponding Purcell factor in excess of 200 000 and a cavity finesse of $2.8\times10^{6}$ is achieved, demonstrating that Toroid microcavities are promising candidates for studies of the Purcell effect, cavity QED or biochemical sensing
