| 1. |
- Berglind, Eilert, et al.
(författare)
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On the Possibilities to Create a Negative Permittivity Metamaterial with Zero Imaginary Part of the Permittivity at a Specific Frequency-Electrical Network Theory Approach
- 2012
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Ingår i: IEEE Journal of Quantum Electronics. - 0018-9197 .- 1558-1713. ; 48:4, s. 507-511
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Tidskriftsartikel (refereegranskat)abstract
- A permittivity function suggested in the literature describing a material that exhibits negative permittivity and no loss at a specific frequency (and losses at other frequencies) is analyzed using electrical network theory. An equivalent circuit of the polarization admittance consisting of RLC components is derived. Further, a proof is given showing that if the admittance is lossless at a specific frequency, then all components with losses (resistances) in the circuit have to be short circuited or blocked or virtually disconnected at this frequency by the use of ideal lossless resonant LC circuits. However, in the literature, inductors in metamaterials are associated with inherently lossy metal nanoparticles, hence invalidating the suggested permittivity function unless a lossless inductor at optical frequencies is found or proved possible.
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| 2. |
- Berglind, Eilert, et al.
(författare)
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Plasmonic/metallic passive waveguides and waveguide components for photonic dense integrated circuits : a feasibility study based on microwave engineering
- 2010
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Ingår i: IET Optoelectronics. - : Institution of Engineering and Technology (IET). - 1751-8768. ; 4:1, s. 1-16
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the potential for dense integration of photonic components, we analyse passive plasmonic/metallic waveguides and waveguide components at optical frequencies by using mostly microwave engineering approaches. Four figures of performance are formulated that are utilised to compare the characteristics of four different slab waveguides with zero frequency cut-off modes. Three of these are metallic based whereas the fourth one, which also serves as a reference, is dielectric based with high index-contrast. It is found that all figures of performance cannot be optimised independently; in particular there is a trade-off between the waveguide Q-value and the transversal field confinement. Microwave methods are used to design several photonic transmission line components. The small Q-value of the metallic waveguides is the main disadvantage when using materials and telecom frequencies of today. Hence plasmonic waveguides do not offer full functionality for some important integrated components, being severe for frequency-selective applications. To achieve a dense integration, it is concluded that new materials are needed that offer Q-values several orders of magnitude higher than metals.
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| 3. |
- Chacinski, Marek, et al.
(författare)
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ETDM Transmitter Module for 100-Gb/s Ethernet
- 2010
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 22:2, s. 70-72
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Tidskriftsartikel (refereegranskat)abstract
- Performance of a packaged distributed-feedback travelling-wave electroabsorption modulator module for data transmission at 100 Gb/s is presented for the first time. Clearly open eye diagrams at 80 Gb/s with an extinction ratio ( ER) of 4.9 dB and 100 Gb/s with ER 4.2 dB ( limited by measurement setup) are demonstrated together with data transmission over 100-m-long standard single-mode fiber and over dispersion-compensated 10-km fiber link.
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| 4. |
- Chacinski, Marek, et al.
(författare)
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Modulation and chirp evaluation of 100 GHz DFB-TWEAM
- 2010
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Ingår i: European Conference on Optical Communication, ECOC. - NEW YORK : IEEE.
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Konferensbidrag (refereegranskat)abstract
- The modulation and chirp performance of an InGaAsP based monolithically integrated distributed feedback (DFB) laser and travelling wave electro-absorption modulator (TWEAM) designed for 100Gb/s operation is presented. Open eye-diagrams at 100Gb/s, and error free 50Gb/s BER (limited by measurement system) were achieved. The chirp factor varied between 1.5 and 0 for absorptions between 10% and 90%.
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| 5. |
- Dai, Daoxin, et al.
(författare)
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Gain enhancement in a hybrid plasmonic nano-waveguide with a low-index or high-index gain medium
- 2011
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Ingår i: Optics Express. - 1094-4087. ; 19:14, s. 12925-12936
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Tidskriftsartikel (refereegranskat)abstract
- A theoretical investigation of a nano-scale hybrid plasmonic waveguide with a low-index as well as high-index gain medium is presented. The present hybrid plasmonic waveguide structure consists of a Si substrate, a buffer layer, a high-index dielectric rib, a low-index cladding, a low-index nano-slot, and an inverted metal rib. Due to the field enhancement in the nano-slot region, a gain enhancement is observed, i.e., the ratio partial derivative G/partial derivative g > 1, where g and G are the gains of the gain medium and the TM fundamental mode of the hybrid plasmonic waveguide, respectively. For a hybrid plasmonic waveguide with a core width of w(co) = 30nm and a slot height of h(slot) = 50nm, the intrinsic loss could be compensated when using a low-index medium with a moderate gain of 176dB/cm. When introducing the high-index gain medium for the hybrid plasmonic waveguide, a higher gain is obtained by choosing a wider core width. For the high-index gain case with h(slot) = 50nm and w(co) = 500nm, a gain of about 200dB/cm also suffices for the compensation of the intrinsic loss.
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| 6. |
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| 7. |
- Dai, Daoxin, et al.
(författare)
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Silicon hybrid plasmonic submicron-donut resonator with pure dielectric access waveguides
- 2011
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Ingår i: Optics Express. - 1094-4087. ; 19:24, s. 23671-23682
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Tidskriftsartikel (refereegranskat)abstract
- Characteristic analyses are given for a bent silicon hybrid plasmonic waveguide, which has the ability of submicron bending (e.g., R = 500nm) even when operating at the infrared wavelength range (1.2 mu m similar to 2 mu m). A silicon hybrid plasmonic submicron-donut resonator is then presented by utilizing the sharp-bending ability of the hybrid plasmonic waveguide. In order to enable long-distance optical interconnects, a pure dielectric access waveguide is introduced for the present hybrid plasmonic submicron-donut resonator by utilizing the evanescent coupling between this pure dielectric waveguide and the submicron hybrid plasmonic resonator. Since the hybrid plasmonic waveguide has a relatively low intrinsic loss, the theoretical intrinsic Q-value is up to 2000 even when the bending radius is reduced to 800nm. By using a three-dimensional finite-difference time-domain (FDTD) method, the spectral response of hybrid plasmonic submicron-donut resonators with a bending radius of 800nm is simulated. The critical coupling of the resonance at around 1423nm is achieved by choosing a 80nm-wide gap between the access waveguide and the resonator. The corresponding loaded Q-value of the submicron-donut resonator is about 220.
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| 8. |
- Holmstrom, Petter, et al.
(författare)
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Composite metal/quantum-dot nanoparticle-array waveguides with compensated loss
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:7, s. 073110-
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Tidskriftsartikel (refereegranskat)abstract
- We calculate the dispersion properties of waveguides composed of near-field-coupled arrays of metal-clad quantum dots (QDs). The high optical loss incurred by operating the metal shells close to resonance is mitigated by using optical gain in the QDs. A condition for achieving loss compensated operation is given based on realistic material parameters and neglecting inhomogeneous broadening. (C) 2010 American Institute of Physics. [doi:10.1063/1.3467845]
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| 9. |
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| 10. |
- Holmström, Petter, et al.
(författare)
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Dielectric function of quantum dots in the strong confinement regime
- 2010
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 107:6
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Tidskriftsartikel (refereegranskat)abstract
- The complex dielectric function of quantum dots (QDs) with a core-shell structure is modeled in the strong confinement regime. These results should be useful for the design of negative epsilon optical metamaterials, where the gain due to QDs could be an essential ingredient. Using the dielectric function it is also shown that conventional expressions for the gain substantially overestimate it for narrow linewidths.
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| 11. |
- Holmström, Petter, et al.
(författare)
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Electro-optic switch based on near-field-coupled quantum dots
- 2014
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Ingår i: Applied Physics A. - : Springer Science and Business Media LLC. - 0947-8396 .- 1432-0630. ; 115:4, s. 1093-1101
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Tidskriftsartikel (refereegranskat)abstract
- The propagation of exciton polaritons in near-field-coupled quantum-dot (QD) chains is modeled by a density-matrix formalism. It is shown that at least for low-temperature operation it is possible using electronically controlled switching by the quantum-confined Stark effect in such QD chains to rival and outperform room-temperature CMOS electronics in footprint and switch energy, though not in speed.
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| 12. |
- Holmström, Petter, et al.
(författare)
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METAL-NANOSHELL/QUANTUM-DOT ARRAY WAVEGUIDES WITH COMPENSATED LOSS
- 2010
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Ingår i: Journal of nonlinear optical physics and materials. - 0218-8635. ; 19:4, s. 595-601
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Tidskriftsartikel (refereegranskat)abstract
- Dispersion properties of nanoarray waveguides composed of near-field-coupled arrays of metal-clad quantum dots (QDs) are calculated. The high loss due to operation of the metal shells close to resonance is mitigated by using optical gain in the QDs. The conditions for achieving loss compensated operation are given, with realistic material parameters and neglecting inhomogeneous broadening.
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| 13. |
- Holmström, Petter, et al.
(författare)
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Passive and active plasmonic nanoarray devices
- 2011
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Ingår i: Metamaterials VI. - : SPIE - International Society for Optical Engineering. - 9780819486608 ; , s. 80700T-1-80700T-6
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Konferensbidrag (refereegranskat)abstract
- Metal nanoparticle arrays offer the possibility to considerably surpass the optical field confinement of silicon waveguides. The properties of directional couplers composed of such plasmonic nanoarrays are analyzed theoretically, while neglecting material losses. It is found that it is possible to generate very compact, submicron length, high fieldconfinement and functionality devices with very low switch energies. We further perform a study of spatial losses in Ag nanoparticle arrays by obtaining the group velocity and the lifetime of the surface plasmon polaritons. The losses are determined for different host permittivities, polarizations, and for spherical and spheroidal particles, with a minimum loss of 12 dB/μm. The possibilities to compensate the losses using gain materials, and the added noise associated with that, is briefly discussed.
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| 14. |
- Holmström, Petter, et al.
(författare)
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Theoretical study of nanophotonic directional couplers comprising near-field-coupled metal nanoparticles
- 2011
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Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 19:8, s. 7885-7893
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Tidskriftsartikel (refereegranskat)abstract
- The properties of integrated-photonics directional couplers composed of near-field- coupled arrays of metal nanoparticles are analyzed theoretically. It is found that it is possible to generate very compact, submicron length, high field-confinement and functionality devices with very low switch energies. The analysis is carried out for a hypothetical lossless silver to demonstrate the potential of this type of circuits for applications in telecom and interconnects. Employing losses of real silver, standalone devices with the above properties are still feasible in optimized metal nanoparticle structures.
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| 15. |
- Lou, Fei, et al.
(författare)
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Design and analysis of ultra-compact EO polymer modulators based on hybrid plasmonic microring resonators
- 2013
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Ingår i: Optics Express. - 1094-4087. ; 21:17, s. 20041-20051
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Tidskriftsartikel (refereegranskat)abstract
- Ultra-compact EO polymer modulators based on hybrid plasmonic microring resonators are proposed, simulated and analyzed. Comparing with Si slot microring modulator, hybrid plasmonic microring modulator shows about 6-times enhancement of the figure of merit when the bending radius is around 510 nm, due to its much larger intrinsic quality factor in sub-micron radius range. Influences of the EO polymer height and Si height on the device's performance are analyzed and optimal design is given. When operating with a bias of 3.6V, the proposed device has optical modulation amplitude of 0.8 and insertion loss of about 1 dB. The estimated power consumption is about 5 fJ/bit at 100 GHz.
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| 16. |
- Lou, Fei
(författare)
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Design, fabrication and characterization of plasmonic components based on silicon nanowire platform
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optical interconnects based on CMOS compatible photonic integrated circuits are regarded as a promising technique to tackle the issues traditional electronics faces, such as limited bandwidth, latency, vast energy consumption and so on. In recent years, plasmonic integrated components have gained great attentions due to the properties of nano-scale confinement, which may potentially bridge the size mismatch between photonic and electronic circuits. Based on silicon nanowire platform, this thesis work studies the design, fabrication and characterization of several integrated plasmonic components, aiming to combine the benefits of Si and plasmonics.The basic theories of surface plasmon polaritons are introduced in the beginning, where we explain the physics behind the diffraction-free confinement. Numerical methods frequently used in the thesis including finite-difference time-domain method and finite-element method are then reviewed. We summarize the device fabrication techniques such as film depositions, e-beam lithography and inductively coupled plasma etching as well as characterization methods, such as direct measurement method, butt coupling, grating coupling etc.Fabrication results of an optically tunable silicon-on-insulator microdisk and III-V cavities in applications as light sources for future nanophotonics interconnects are briefly discussed. Afterwards we present in details the experimental demonstrations and novel design of plasmonic components.Hybrid plasmonic waveguides and directional couplers with various splitting ratios are firstly experimentally demonstrated. The coupling length of two 170 nm wide waveguides with a separation of 140 nm is only 1.55 µm. Secondly, an ultracompact polarization beam splitter with a footprint of 2×5.1 μm2 is proposed. The device features an extinction ratio of 12 dB and an insertion loss below 1.5 dB in the entire C-band. Thirdly, we show that plasmonics offer decreased bending losses and enhanced Purcell factor for submicron bends. Novel hybrid plasmonic disk, ring and donut resonators with radii of ~ 0.5 μm and 1 μm are experimentally demonstrated for the first time. The Q-factor of disks with 0.5 μm radii are , corresponding to Purcell factors of . Thermal tuning is also presented. Fourthly, we propose a design of electro-optic polymer modulator based on plasmonic microring. The figure of merit characterizing modulation efficiency is 6 times better comparing with corresponding silicon slot polymer modulator. The device exhibits an insertion loss below 1 dB and a power consumption of 5 fJ/bit at 100 GHz. At last, we propose a tightly-confined waveguide and show that the radius of disk resonators based on the proposed waveguide can be shrunk below 60 nm, which may be used to pursue a strong light-matter interaction.The presented here novel components confirm that hybrid plasmonic structures can play an important role in future inter- and intra-core computer communication systems.
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| 17. |
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| 18. |
- Lou, Fei, et al.
(författare)
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Experimental demonstration of ultra-compact directional couplers based on silicon hybrid plasmonic waveguides
- 2012
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 100:24, s. 241105-
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Tidskriftsartikel (refereegranskat)abstract
- Hybrid plasmonic waveguides and directional couplers have been experimentally demonstrated. Using a direct measurement method, the propagation loss of a 170 nm wide waveguide is measured to be 0.08 dB/mu m at 1550 nm when the thickness of low-index region is 56 nm. Ultra-compact directional couplers based on such hybrid plasmonic waveguides are demonstrated with gaps of 140 nm, 185 nm, 235 nm, and 290 nm. The corresponding coupling lengths measured are 1.55 mu m, 2.2 mu m, 3.2 mu m, and 4.8 mu m, respectively, which are in very good agreement with the simulations. These ultra-compact devices can be potentially used in future ultra-dense photonic integrated circuits.
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| 19. |
- Lou, Fei, et al.
(författare)
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Hybrid plasmonic microdisk resonators for optical interconnect applications
- 2013
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Ingår i: Integrated Optics. - : SPIE - International Society for Optical Engineering. - 9780819495839 ; , s. 87810X-
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Konferensbidrag (refereegranskat)abstract
- In this paper, we present our theoretical and experimental work on hybrid plasmonic microdisks. The 170 nm wide access waveguide is first simulated and characterized, and shows a propagation loss about 0.08 dB/mu m. 3-D FDTD simulations are then used to investigate the lower limit of the bending radius of the hybrid plasmonic microdisk. Microdisks with radius around 500 nm are fabricated, characterized, and analyzed. The 5th and 4th order resonances are experimentally observed around 1412 nm and 1625 nm. The extinction ratios of the two resonances are measured to be 5.5dB and above 10dB, respectively. The measured intrinsic quality factors are 350 and 110, respectively. Comparisons are also made between the theoretical and experimental results. The demonstrated ultra-small hybrid plasmonic microdisk may find applications in low-power-consumption modulators, nano laser cavities with large Purcell-factor, molecule sensors, and others.
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| 20. |
- Lou, Fei, et al.
(författare)
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Photonic devices based on silicon hybrid plasmonic waveguides
- 2012
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Ingår i: 2012 Asia Communications And Photonics Conference (ACP). - Washington, D.C. : Optica Publishing Group. ; , s. AS2H.2-
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Konferensbidrag (refereegranskat)abstract
- A 170 nm wide hybrid plasmonic waveguide with a loss of 0,08 dB/mu m is demonstrated experimentally. Directional couplers with different gaps and microdisks with 0.5 mu m radius based on such waveguides are also presented.
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| 21. |
- Lou, Fei, et al.
(författare)
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Sub-wavelength microdisk resonator based on hybrid plasmonic waveguides
- 2012
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Ingår i: Information Optoelectronics, Nanofabrication and Testing, IONT 2012. - 9781557529602
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Konferensbidrag (refereegranskat)abstract
- Based on hybrid plasmonic waveguides, microdisk resonators with radii of 0.5 μm and FSRs of about 200 nm are simulated and experimentally demonstrated. Thermal tuning of the devices in 6 nm range is also presented.
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| 22. |
- Lou, Fei, et al.
(författare)
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Ultra-sharp bends based on hybrid plasmonic waveguides
- 2014
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Ingår i: European Conference on Optical Communication, ECOC.
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Konferensbidrag (refereegranskat)abstract
- To explore the potentials of hybrid plasmonics, ultrasharp 90 degree bends and resonators based on silicon waveguide and hybrid plasmonic waveguides are simulated and analyzed. Experimental demonstrations of ring and donut resonators based on hybrid plasmonics are also presented.
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| 23. |
- Lou, Fei, et al.
(författare)
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Whispering gallery mode nanodisk resonator based on layered metal-dielectric waveguide
- 2014
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Ingår i: Optics Express. - 1094-4087. ; 22:7, s. 8490-8502
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Tidskriftsartikel (refereegranskat)abstract
- This paper proposes a layered metal-dielectric waveguide consisting of a stack of alternating metal and dielectric films which enables an ultracompact mode confinement. The properties of whispering gallery modes supported by disk resonators based on such waveguides are investigated for achieving a large Purcell factor. We show that by stacking three layers of 10 nm thick silver with two layers of 50 nm dielectric layers (of refractive index n) in sequence, the disk radius can be as small as 61 nm similar to lambda(0) / (7n) and the mode volume is only 0.0175 (lambda(0) / (2n))(3). When operating at 40 K, the cavity's Q-factor can be similar to 670; Purcell factor can be as large as 2.3x10(4), which is more than five times larger than that achievable in a metal-dielectric-metal disk cavity in the same condition. When more dielectric layers with smaller thicknesses are used, even more compact confinement can be achieved. For example, the radius of a cavity consisting of seven dielectric-layer waveguide can be shrunk down to lambda(0) / (13.5n), corresponding to a mode volume of 0.005 lambda(0) / (2n))(3), and Purcell factor can be enhanced to 7.3x10(4) at 40 K. The influence of parameters like thicknesses of dielectric and metal films, cavity size, and number of dielectric layers is also comprehensively studied. The proposed waveguide and nanodisk cavity provide an alternative for ultracompact light confinement, and can find applications where a strong light-matter interaction is necessary.
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| 24. |
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| 25. |
- Naruse, Makoto, et al.
(författare)
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Analysis of optical near-field energy transfer by stochastic model unifying architectural dependencies
- 2014
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 115:15, s. 154306-
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Tidskriftsartikel (refereegranskat)abstract
- We theoretically and experimentally demonstrate energy transfer mediated by optical near-field interactions in a multi-layer InAs quantum dot (QD) structure composed of a single layer of larger dots and N layers of smaller ones. We construct a stochastic model in which optical near-field interactions that follow a Yukawa potential, QD size fluctuations, and temperature-dependent energy level broadening are unified, enabling us to examine device-architecture-dependent energy transfer efficiencies. The model results are consistent with the experiments. This study provides an insight into optical energy transfer involving inherent disorders in materials and paves the way to systematic design principles of nanophotonic devices that will allow optimized performance and the realization of designated functions.
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