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| 2. |
- Dai, Daoxin, et al.
(författare)
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A silicon-based hybrid plasmonic waveguide with a metal cap for a nano-scale light confinement
- 2009
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Ingår i: Optics Express. - 1094-4087. ; 17:19, s. 16646-16653
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Tidskriftsartikel (refereegranskat)abstract
- A hybrid plasmonic waveguide with a metal cap on a silicon-on-insulator rib (or slab) is presented. There is a low-index material nano-layer between the Si layer and the metal layer. The field enhancement in the nano-layer provides a nano-scale confinement of the optical field (e. g., 50nm x 5nm) when operates at the optical wavelength lambda = 1550nm. The theoretical investigation also shows that the present hybrid plasmonic waveguide has a low loss and consequently a relatively long propagation distance (on the order of several tens of lambda).
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| 3. |
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| 4. |
- Dai, Daoxin, et al.
(författare)
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Compact Microracetrack Resonator Devices Based on Small SU-8 Polymer Strip Waveguides
- 2009
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Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 21:1-4, s. 254-256
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Tidskriftsartikel (refereegranskat)abstract
- Compact microracetrack resonator (MRR) devices are presented with small SU-8 polymer strip waveguides. The SU-8 strip waveguide has an SU-8 polymer core (n similar to 1.573), a SiO2 buffer (n similar to 1.445), and an air cladding. The fabricate straight waveguide has a low propagation loss of about 0.1. dB/mm. With such a high index-contrast optical waveguide, a compact MRR with a small bending radius (similar to 150 mu m) are designed and fabricated. The measured spectral responses of the through/drop ports show a Q-factor of 8000.
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| 5. |
- Dai, Daoxin, et al.
(författare)
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Compact Microring Resonator With 2 x 2 Tapered Multimode Interference Couplers
- 2009
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Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 27:21, s. 4878-4883
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Tidskriftsartikel (refereegranskat)abstract
- Compact microring resonator devices are realized by using a small SU-8 polymer strip waveguide that has an SU-8 polymer core (n similar to 1.573), an SiO2 buffer (n similar to 1.445), and an air cladding. Due to the high index contrast of the optical waveguide, a small bending radius (similar to 150 mu m) is used for the MRR. To enhance the coupling between the access optical waveguides and the microring, 2 x 2 multimode interference couplers are used. The measured spectral response of the through port shows a high extinction ratio of over 15 dB and a 3-dB bandwidth of about 0.38 nm (corresponding to a moderate Q-value of similar to 4500).
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| 6. |
- Dai, Daoxin, et al.
(författare)
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Compact silicon-based wavelength-selective photonic integrated devices and the applications
- 2009
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Ingår i: SILICON PHOTONICS IV. - : SPIE-INT SOC OPTICAL ENGINEERING. - 9780819474667
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Konferensbidrag (refereegranskat)abstract
- In wavelength-division multiplexing systems, it is important to develop various wavelength-selective components to have flexible and reconfigurable nodes. When using conventional optical waveguides with low index contrast, the sizes of these wavelength-selective components are usually several cm(2), which is too large to integrate more components in a single wafer or chip. In order to improve the integration density and reduce the cost, it is desirable to minimize the component sizes. In our case, two kinds of strongly-confined optical waveguides on silicon wafer are considered for compact wavelength-selective devices. One is the popular silicon-on-insulator (SOI) nanowire and the other is SU-8 strip optical waveguide with an air cladding and a SiO2 insulator layer on a Si substrate. In this paper, we give a review of our recent work on wavelength-selective photonic integrated devices based on these two kinds of silicon-based optical waveguides with strong-confinements. Arrayed-waveguide grating (AWG) and microring resonator (MRR), which are two typical wavelength-selective components are included. First we give a review for several new layouts for SOI-nanowire AWG to have a further size-reduction and our novel designs for diminishing the polarization dependency of AWGs. Secondly we present the design and fabrication of multimode interference (MMI) couplers for MRRs. A novel design method for tapered MMI couplers is presented and the diminishment of polarization in a MMI coupler is proposed by optimizing the tapered MMI section. We also present our experimental results on optical sensor combining MRRs and micro-fluid channel. The measured sensitivity is about 180nm/RIU.
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| 7. |
- Dai, Daoxin, et al.
(författare)
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Compact silicon-on-insulator-based multimode interference coupler with bilevel taper structures
- 2005
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Ingår i: Applied Optics. - 1559-128X .- 2155-3165. ; 44:24, s. 5036-5041
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Tidskriftsartikel (refereegranskat)abstract
- A novel compact silicon-on-insulator- (SOI-)based multimode interference (MMI) coupler with bilevel taper structures was designed. The MMI section and the S-bend sections of the input-output waveguides are deeply etched. The input-output waveguides connecting to single-mode fibers or other photonic light circuits are etched shallowly to yield single-mode operation. A bilevel taper is introduced in the transition region between the shallowly and deeply etched regions. It is predicted theoretically that this design will not only improve the quality of the self-imaging in the MMI section but will also make the structure compact. Both the excess loss and the nonuniformity of the MMI coupler are reduced. By use of a three-dimensional beam propagation method, the performance of a 1 × 4 MMI coupler based on a SOI is simulated as a numerical example of the novel design. The simulated nonuniformity and the excess loss are approximately 0.0285 and 0.2 dB, respectively.
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| 9. |
- 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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| 10. |
- Dai, Daoxin, et al.
(författare)
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Design and fabrication of ultrasmall arrayed waveguide grating multiplexers based on Si nanowire waveguides
- 2007
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Ingår i: Optoelectronics Letters. - : Springer Science and Business Media LLC. - 1673-1905. ; 3:1, s. 7-9
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Tidskriftsartikel (refereegranskat)abstract
- The large refractive index difference between Si and SiO2 makes it possible to realize ultrasmall photonic integrated circuits. A 5 × 5 ultracompact arrayed waveguide grating multiplexer based on 500×250 nm Si nanowire waveguides is designed and fabricated by using the technologies of E-beam writing and amorphous-Si deposition. The measured channel spacing is about 1.5 nm (close to the design value) and the channel crosstalk is about -8 dB.
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