| 1. |
- Berrier, Audrey, et al.
(författare)
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Accumulated sidewall damage in dry etched photonic crystals
- 2009
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Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 27:4, s. 1969-1975
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Tidskriftsartikel (refereegranskat)abstract
- Evidence for accumulated damage is provided by investigating the effect of etch duration on the carrier lifetime of an InGaAsP quantum well (QW) inside the InP-based photonic crystal (PhC) structures. It is found that once the quantum well is etched through, additional etching reduces the carrier lifetimes from 800 to 70 ps. The surface recombination velocity (SRV) at the exposed hole sidewalls is determined from the measured carrier lifetimes of the PhC fields with different lattice parameters. The observed variation in the SRV with etch duration also confirms the presence of accumulated sidewall damage. It increases from 6x10(3) to 1.2x10(5) cm s(-1) as the etching time increases from 3 to 50 min. A geometric model based on sputtering theory and on the evolution of the hole shape is developed to explain the accumulation of sidewall damage. The model is used to estimate the number of impact events from sputtered species reaching the QW sidewalls, and the variation in the accumulated impact events with etch duration is shown to be qualitatively consistent with the experimental observations. Finally, the results suggest a new method for tailoring the carrier lifetimes in PhC membrane structures.
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| 2. |
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| 3. |
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| 4. |
- Berrier, Audrey, et al.
(författare)
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Impact of dry-etching induced damage in InP-based photonic crystals
- 2008
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Ingår i: PHOTONIC CRYSTAL MATERIALS AND DEVICES VIII. - : SPIE. ; , s. U9890-U9890
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Konferensbidrag (refereegranskat)abstract
- In this work variations of the carrier lifetime in a GaInAsP/InP quantum well in two-dimensional PhC structures etched by Ar/Cl-2 chemically assisted ion beam etching as a function of the processing parameters is investigated. It is shown that the deposition conditions of the SiO2 mask material and its coverage as well as other process steps such as annealing affect the carrier lifetimes. However the impact of patterning the semiconductor on the carrier lifetime is dominant, showing over an order of magnitude reduction. For given PhC lattice parameters, the sidewall damage is shown to be directly related to the measured carrier lifetimes. A simple qualitative model based on sputtering theory and assuming a conical hole-shape development during etching is used to explain the experimental results.
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| 5. |
- Cai, Tao, et al.
(författare)
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An efficiently tunable microring resonator using a liquid crystal-cladded polymer waveguide
- 2010
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Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:12, s. 121109-
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Tidskriftsartikel (refereegranskat)abstract
- An electrically tunable polymer microring resonator of large tunability and low applied voltage is demonstrated using active liquid crystal (LC) cladding. A large tuning range of 0.73 nm is achieved due to more homogenous LC molecular alignment and enhanced interaction of the light with the LC cladding in the simplified polymer waveguide structure. The operating voltage decreases to 10 V with a threshold of only 3 V by the utilization of interdigital electrodes.
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| 8. |
- Dai, Daoxin, et al.
(författare)
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Deeply etched SiO2 ridge waveguide for sharp bends
- 2006
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Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 24:12, s. 5019-5024
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Tidskriftsartikel (refereegranskat)abstract
- A deeply etched SiO2 ridge waveguide including the buffer, core, and cladding is presented for realizing sharp bends. The present SiO2 ridge waveguide has a strong confinement at the lateral direction, while it has a weak confinement at the vertical direction. Due to the strong confinement, a sharp bend (with a very small bending radius of about 10 mu m) is obtained for an acceptable bending loss. A detailed analysis of the loss in a bent waveguide is given by using a finite-difference method. In order to reduce the transition loss, a narrow bending section with an optimal lateral offset is used. A low leakage loss is obtained by using wide straight waveguides, and linear tapers are used to connect the wide straight section and narrow bent sections.
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| 9. |
- 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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| 10. |
- 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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