| 1. |
- Berrier, Audrey, et al.
(författare)
-
Accumulated sidewall damage in dry etched photonic crystals
- 2009
-
Ingår i: Journal of Vacuum Science & Technology B. - : American Vacuum Society. - 1071-1023 .- 1520-8567. ; 27:4, s. 1969-1975
-
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.
|
|
| 2. |
|
|
| 3. |
|
|
| 4. |
- Berrier, Audrey, et al.
(författare)
-
Impact of dry-etching induced damage in InP-based photonic crystals
- 2008
-
Ingår i: PHOTONIC CRYSTAL MATERIALS AND DEVICES VIII. - : SPIE. ; , s. U9890-U9890
-
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.
|
|
| 5. |
- Cai, Tao, et al.
(författare)
-
An efficiently tunable microring resonator using a liquid crystal-cladded polymer waveguide
- 2010
-
Ingår i: Applied Physics Letters. - : AIP Publishing. - 0003-6951 .- 1077-3118. ; 97:12, s. 121109-
-
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.
|
|
| 6. |
|
|
| 7. |
|
|
| 8. |
- Dai, Daoxin, et al.
(författare)
-
Deeply etched SiO2 ridge waveguide for sharp bends
- 2006
-
Ingår i: Journal of Lightwave Technology. - 0733-8724 .- 1558-2213. ; 24:12, s. 5019-5024
-
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.
|
|
| 9. |
- Dai, Daoxin, et al.
(författare)
-
Gain enhancement in a hybrid plasmonic nano-waveguide with a low-index or high-index gain medium
- 2011
-
Ingår i: Optics Express. - 1094-4087. ; 19:14, s. 12925-12936
-
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.
|
|
| 10. |
- Dai, Daoxin, et al.
(författare)
-
Silicon hybrid plasmonic submicron-donut resonator with pure dielectric access waveguides
- 2011
-
Ingår i: Optics Express. - 1094-4087. ; 19:24, s. 23671-23682
-
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.
|
|
| 11. |
- Dai, Daoxin, et al.
(författare)
-
Theoretical Investigation for Reducing Polarization Sensitivity in Si-Nanowire-Based Arrayed-Waveguide Grating (de)Multiplexer With Polarization-Beam-Splitters and Reflectors
- 2009
-
Ingår i: IEEE Journal of Quantum Electronics. - : Institute of Electrical and Electronics Engineers (IEEE). - 0018-9197 .- 1558-1713. ; 45:5-6, s. 654-660
-
Tidskriftsartikel (refereegranskat)abstract
- A novel design for reducing polarization sensitivity in silicon-on-insulator-based arrayed-waveguide grating (AWG) (de)multiplexer is presented. Each arrayed waveguide has two sections separated by a polarization beam splitter (PBS). These two sections have different core widths and length differences. With these PBSs, one polarization is reflected and the other one goes through. The through polarization enters the second section and is then reflected by a reflector at the end of the second section of the arrayed waveguide. The theoretical simulation shows that one can diminish greatly the polarization sensitivity of both the central channel wavelength and the channel spacing by optimizing the core width and length difference of the second section. The design procedure and formulas are given and an appropriate diffraction order is chosen to obtain a good fabrication tolerance. As an example, an ultrasmall (82.2 x 85.1 mu m(2)) AWG (de)multiplexer with eight channels and a channel spacing of 4 nm is designed to have minimized polarization sensitivity and Bragg-grating PBSs and photonic crystal reflectors are used.
|
|
| 12. |
- Ge, Xiaochen, et al.
(författare)
-
Ultra-compact channel drop filter based on photonic crystal nanobeam cavities utilizing a resonant tunneling effect
- 2014
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 39:24, s. 6973-6976
-
Tidskriftsartikel (refereegranskat)abstract
- The design, fabrication, and characterization of a compact photonic crystal nanobeam drop filter based on the tunneling effect of the degenerate modes are presented. The degeneracy was achieved by tuning the coupling distance between the nanobeam and input/output waveguides. The tunneling effect of degenerate resonances with different symmetries has been verified experimentally. Channel drop filters with an extinction ratio larger than 10 dB and a quality factor of similar to 5000 have been experimentally demonstrated.
|
|
| 13. |
- Guan, Xiaowei, et al.
(författare)
-
Ultracompact and broadband polarization beam splitter utilizing the evanescent coupling between a hybrid plasmonic waveguide and a silicon nanowire
- 2013
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 38:16, s. 3005-3008
-
Tidskriftsartikel (refereegranskat)abstract
- An ultracompact polarization beam splitter (PBS) is proposed based on an asymmetrical directional coupler consisting of a silicon hybrid plasmonic waveguide (HPW) and a silicon nanowire. The widths of the two coupling waveguides are chosen so that the phase-matching condition is satisfied for TE polarization only while the phase mismatch is significant for TM polarization. A sharply bent silicon HPW is connected at the thru port to play the role of polarizer by utilizing its polarization-dependent loss. With the present principle, the designed PBS has a footprint as small as only similar to 1.9 mu m x 3.7 mu m, which is the shortest PBS reported until now, even when large waveguide dimensions (e. g., the waveguide widths w(1,2) = similar to 300 nm and the gap width w(gap) = similar to 200 nm) are chosen to simplify the fabrication process. The numerical simulations show that the designed PBS has a very broad band (similar to 120 nm) with an extinction ratio >12 dB and a large fabrication tolerance to allow a waveguide width variation of similar to 30 nm.
|
|
| 14. |
- Guan, Xiaowei, et al.
(författare)
-
Ultrasmall Directional Coupler and Disk-resonantor Based on Nano-scale Silicon Hybrid Plasmonic Waveguides
- 2012
-
Ingår i: 2012 Asia Communications And Photonics Conference (ACP). - Washington, D.C. : OSA. - 9781467362740 ; , s. AS2H.4-
-
Konferensbidrag (refereegranskat)abstract
- Nanophotonic integrated devices based on nano-scale silicon hybrid plasmonic waveguides have been demonstrated experimentally, including directional couplers and disk-resonators. The temperature-dependence of the hybrid plasmonic disk-resonators is also characterized.
|
|
| 15. |
- He, Sailing, et al.
(författare)
-
Some progress in integrated photonics
- 2005
-
Ingår i: OPTOELECTRONIC DEVICES AND INTEGRATION. - : SPIE. - 0819455997 ; , s. 405-413
-
Konferensbidrag (refereegranskat)abstract
- A review is presented on some progress we have made recently in planar integrated photonics including arrayed-waveguide gratings (AWGs) and etched diffraction gratings (EDGs), multimode interference (MMI) couplers/splitters, and spot-size converters. Some novel structures and design methods are summarized and presented.
|
|
| 16. |
- Jiao, Yuqing, et al.
(författare)
-
Accurate and efficient simulation for silicon-nanowire-based multimode interference couplers with a 3D finite-element mode-propagation analysis
- 2010
-
Ingår i: Journal of the Optical Society of America. B, Optical physics. - : Optical Society of American (OSA). - 0740-3224 .- 1520-8540. ; 27:9, s. 1813-1818
-
Tidskriftsartikel (refereegranskat)abstract
- A three-dimensional (3D) finite-element mode-propagation analysis is presented to give an accurate and efficient simulation for silicon-nanowire- based multimode interference (MMI) couplers. For the presented numerical method, a finite-element method mode solver is used to calculate the mode profiles and the propagation constants in a multimode section. The comparison between the presented method and some other numerical methods [e.g., finite-difference time-domain (FDTD) method, beam propagation methods, etc.] is also shown. It is shown that the presented numerical method gives simulation results very close to those from the 3D FDTD (with a deviation less than 1%). Therefore, it is very convenient for the design of Si-nanowire-based MMI couplers.
|
|
| 17. |
- Jiao, Yuqing, et al.
(författare)
-
An integrated optical mixer based on SU8 polymer for PDM-QPSK demodulation
- 2011
-
Ingår i: IEEE Photonics Technology Letters. - 1041-1135. ; 23:20, s. 1490-1492
-
Tidskriftsartikel (refereegranskat)abstract
- This letter presents the design and fabrication of an optical mixer based on SU8 polymer for the demodulation of polarization division multiplexed-quadrature phase shift keying (PDM-QPSK) signals. The mixer consists of two novel polarization beam splitters (PBSs) and two 4 × 4 multimode interference (MMI) couplers. It is the first polymer-based optical mixer incorporated with PDM functionality. The experimental results show good performances of the mixer.
|
|
| 18. |
- Jiao, Y. Q., et al.
(författare)
-
Shortened Polarization Beam Splitters With Two Cascaded Multimode Interference Sections
- 2009
-
Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 21:20, s. 1538-1540
-
Tidskriftsartikel (refereegranskat)abstract
- This letter presents a design for shortening the length of a polarization beam splitter (PBS) by using two cascaded multimode interference (MMI) sections with different widths. By optimizing the MMI parameters, a short PBS of good performance is achieved. The total length of the PBS is reduced to about 1/28 of that of a conventional design.
|
|
| 19. |
- Shi, Yaocheng, et al.
(författare)
-
A polarization-insensitive 1310/1550-nm demultiplexer based on sandwiched multimode interference waveguides
- 2007
-
Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 19:21-24, s. 1789-1791
-
Tidskriftsartikel (refereegranskat)abstract
- A polarization-insensitive dual-wavelength demultiplexer based on sandwiched multimode interference waveguides is presented. Polarization-insensitive multimode waveguides are achieved first by choosing a suitable refractive index of the SiNx middle region. The demultiplxing function is then realized by adjusting the width and length of the multimode region. Simulation results obtained from three-dimensional beam-propagation method show that the demultiplexer can work at 1310- and 1550-nm bands for both polarizations simultaneously with a low insertion loss and a broad bandwidth.
|
|
| 20. |
- Shi, Yaocheng, et al.
(författare)
-
An ultra-compact polarization insensitive directional coupler
- 2008
-
Ingår i: AOE 2008. - 9781557528636
-
Konferensbidrag (refereegranskat)abstract
- We investigate the lag-effect in the dry etching process. In one etch step, asymmetric waveguides with a shallow groove in between can be fabricated. This special property can be utilized for the design of an ultra-compact polarization insensitive directional coupler.
|
|
| 21. |
- Shi, Yaocheng, et al.
(författare)
-
Design of a compact multimode interference coupler based on deeply-etched SiO2 ridge waveguides
- 2007
-
Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 271:2, s. 404-407
-
Tidskriftsartikel (refereegranskat)abstract
- A compact multimode interference (MMI) coupler is realized by using deeply-etched SiO2 ridge waveguides, which have a strong confinement in the lateral direction and improve the quality of self-images in the MMI section, A 1 x 4 MMI coupler is designed as a numerical example and demonstrates good performances such as a low insertion (0.0275 dB) and small non-uniformity (0.0507 dB). The total device size of the present MMI coupler is reduced to about 1/16 of that based on SiO2 buried waveguides.
|
|
| 22. |
- Shi, Yaocheng, et al.
(författare)
-
Design of a flat-field arrayed waveguide grating
- 2005
-
Ingår i: Optoelectronic Devices and Integration. - : SPIE. ; , s. 500-507
-
Konferensbidrag (refereegranskat)abstract
- A curved image plane is usually used in a conventional Rowland-type AWG For some applications (e.g., sensing), a straight image plane is desirable so that the output field at the image plane can be received directly with a detector-array. If one simply chooses a flat output plane (instead of a circular output curve) without optimization for a conventional AWG of Rowland circle type, some considerable aberrations will be introduced, which degrade the performances of the AWG The aberrations are calculated and analyzed with an optical path function. A three-stigmatic-point method is used to optimize the design of an AWG with a straight image plane and minimize the aberrations. In this design, the aberrations at three special wavelengths are removed. The first order aberrations at all wavelengths are also eliminated. An 80-channel flat-field AWG is designed as an example. The results show that the aberrations are reduced greatly and a good spectral response with tolerated side-lodes is obtained.
|
|
| 23. |
- Shi, Yaocheng, et al.
(författare)
-
Design of a Polarization Insensitive Triplexer Using Directional Couplers Based on Submicron Silicon Rib Waveguides
- 2009
-
Ingår i: Journal of Lightwave Technology. - : Institute of Electrical and Electronics Engineers (IEEE). - 0733-8724 .- 1558-2213. ; 27:11, s. 1443-1447
-
Tidskriftsartikel (refereegranskat)abstract
- An ultracompact triplexer which could be used for both polarizations is designed by utilizing directional couplers based on submicron silicon rib waveguides. First, the polarization insensitive directional couplers are realized by carefully choosing cross-sectional geometry of the waveguide. The length of the coupling region in the first directional coupler is chosen to separate the three wavelengths ( i.e., 1490 nm to one port, 1310 and 1550 nm to the other port). The second directional coupler separates the wavelengths of 1310 and 1550 nm. For the channel of 1490 nm, an additional directional coupler is used to reduce the crosstalk from the 1310 and 1550 nm channels. The total length of the present triplexer is only 400 and simulation with three-dimensional Beam Propagation Method shows good performances for both polarizations.
|
|
| 24. |
- Shi, Yaocheng, 1981-
(författare)
-
Design, Simulation and Characterization of Some Planar Lightwave Circuits
- 2008
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Optical devices based on planar lightwave circuit (PLC) technology have the advantages of small size, high reliability, possibility for large scale production, and potential integration with electronics. These devices are widely employed in optical telecommunications, sensing, data storage, imaging, and signal processing. This thesis focuses on some selected PLC based devices, such as power splitters, demultiplexers, triplexers and polarization beam splitters. First, the basic principle of the waveguides and the simulation methods for PLC devices are discussed. A novel effective index method is introduced to reduce a two-dimensional structure to a one-dimensional one, and can be implemented for arbitrarily shaped waveguides. Numerical methods, such as finite-difference mode solver, beam propagation method, finite-difference time-domain method are introduced to analysis the mode profile of the waveguides, and the propagation properties of light in PLC devices. Multimode interference (MMI) couplers are widely used in many PLCs, such as power splitters, ring lasers, optical switches, and wavelength division multiplexers/demultiplexers. In this work, concepts for improving the self-imaging quality of MMI couplers are analyzed and new designs are proposed. A significant improvement in performance together with compact sizes were obtained with taper sections at the input/output of MMI couplers based on SOI, and deeply etched ridges in MMI couplers based on SiO2. A polarization insensitive dual wavelength demultiplexer based on sandwiched MMI waveguides was presented. Novel devices including triplexers and polarization beam splitters were realized by using photonic crystal (PhC) structures. Two stages of directional couplers based on PhC waveguides are cascaded to form an ultracompact triplexer. The special decoupling property of the PhC waveguide based directional coupler was utilized in the design. A novel polarization beam splitter was realized by combining a MMI coupler and a PhC which works as a polarization sensitive reflector. Finally, fabrication and optical characterization of an ultra-compact directional coupler and PhC structures in InP are presented. In a single etching step, by using the lag-effect in inductively coupled plasma reactive ion etching, a compact directional coupler (55 μm) is demonstrated. Carrier life times in PhC structures etched by chemically assisted ion beam etching were investigated, for emitter and switching applications.
|
|
| 25. |
- Shi, Yaocheng, et al.
(författare)
-
Experimental demonstration of an ultracompact polarization beamsplitter based on a multimode interference coupler with internal photonic crystals
- 2010
-
Ingår i: Optical Engineering. - : SPIE-Intl Soc Optical Eng. - 0091-3286 .- 1560-2303. ; 49:6, s. 060503-
-
Tidskriftsartikel (refereegranskat)abstract
- The fabrication and characterization of a compact InP-based polarization beamsplitter (PBS) is presented. A multimode interference (MMI) coupler with an internal air hole photonic crystal (PhC) section is utilized to separate the two polarizations. The PhC structure in the middle of the MMI is polarization dependent, so that one polarization is reflected and the other one is transmitted; both are collected by the respective output ports of the MMI coupler. The obtained experimental results show that the PBS as short as similar to 400 mu m has an extinction ratio as large as 15 dB.
|
|
| 26. |
- Shi, Yaocheng, et al.
(författare)
-
Improved performance of a silicon-on-insulator-based multimode interference coupler by using taper structures
- 2005
-
Ingår i: Optics Communications. - : Elsevier BV. - 0030-4018 .- 1873-0310. ; 253:4-6, s. 276-282
-
Tidskriftsartikel (refereegranskat)abstract
- Multimode effects in a multimode interference (MMI) coupler based on silicon-on-insulator (SOI) are analyzed. Multimode interference in the vertical direction of an SOI-based MMI device degrades the self-imaging quality. Taper structures are introduced at the junction between input/output waveguides and multimode region to suppress the excitation of the undesired vertical modes. A 1 x 4 MMI coupler of low insertion loss (0.101 dB) and small non-uniformity (0.102 dB) is designed as a numerical example.
|
|
| 27. |
- Shi, Yaocheng, et al.
(författare)
-
Novel ultracompact triplexer based on photonic crystal waveguides
- 2006
-
Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 18:21-24, s. 2293-2295
-
Tidskriftsartikel (refereegranskat)abstract
- Two stages of directional couplers based on photonic crystal waveguides Are cascaded to form an ultracompact triplexer. The directional couplers are decoupled at the wavelength of 1310 rum. The length of the coupling region in the first directional coupler is chosen to separate the other two wavelengths (i.e., 1490 and 1550 nm), and the coupling region is tapered to improve the extinction ratios. The second directional coupler separates the wavelengths of 1490 and 1310 run. For the channel of 1550 nm, an additional directional coupler is used to reduce the crosstalk from the channels of 1490 and 1310 nm. The total size of the present triplexer is only 50 mu m x 20 mu m, and the good performance is verified with finite-difference time-domain simulation.
|
|
| 28. |
- Shi, Yaocheng, et al.
(författare)
-
Proposal for an ultracompact polarization-beam splitter based on a photonic-crystal-assisted multimode interference coupler
- 2007
-
Ingår i: IEEE Photonics Technology Letters. - : Institute of Electrical and Electronics Engineers (IEEE). - 1041-1135 .- 1941-0174. ; 19:9-12, s. 825-827
-
Tidskriftsartikel (refereegranskat)abstract
- An ultracompact polarization-beam splitter (PBS) combining a multimode interference (MMI) coupler and some photonic crystal (PC) structures is presented. The MMI coupler is designed to collect polarized powers reflected by or transmitted through an internal PC sturcture. The simulation result shows that the designed PBS is very short (about 50 mu m), and has a low insertion loss, a high extinction ratio, and a broad bandwidth.
|
|
| 29. |
- Shi, Yaocheng, et al.
(författare)
-
Ultracompact directional couplers realized in InP by utilizing feature size dependent etching
- 2008
-
Ingår i: Optics Letters. - 0146-9592 .- 1539-4794. ; 33:17, s. 1927-1929
-
Tidskriftsartikel (refereegranskat)abstract
- We present the design, fabrication, and measurement of an ultracompact directional coupler in InP/InGaAsP/InP. By utilizing the lag effect in the dry etching process, in one etch step, deeply etched asymmetric waveguides with a shallow groove in between are fabricated. This special property enhances the coupling efficiency for the directional coupler and thus makes the device ultracompact. We demonstrate directional couplers as short as 55 mu m, which is only 1/30th the length of the conventional design.
|
|
| 30. |
- Wang, J., et al.
(författare)
-
Sub-μm2 power splitters by using silicon hybrid plasmonic waveguides
- 2011
-
Ingår i: Optics Express. - : Optical Society of America. - 1094-4087. ; 19:2, s. 838-847
-
Tidskriftsartikel (refereegranskat)abstract
- Nano-scale power splitters based on Si hybrid plasmonic waveguides are designed by utilizing the multimode interference (MMI) effect as well as Y-branch structure. A three-dimensional finite-difference time-domain method is used for simulating the light propagation and optimizing the structural parameters. The designed 1×2 50:50 MMI power splitter has a nano-scale size of only 650 nm×530 nm. The designed Y-branch power splitter is also very small, i.e., about 900 nm×600 nm. The fabrication tolerance is also analyzed and it is shown that the tolerance of the waveguide width is much larger than±50 nm. The power splitter has a very broad band of over 500 nm. In order to achieve a variable power splitting ratio, a 2×2 two-mode interference coupler and an asymmetric Y-branch are used and the corresponding power splitting ratio can be tuned in the range of 97.1%:2.9%-1.7%:98.3% and 84%:16%-16%:84%, respectively. Finally a 1×4 power splitter with a device footprint of 1.9 μm×2.6 μm is also presented using cascaded Y-branches.
|
|
| 31. |
- Wang, Zhechao, et al.
(författare)
-
Experimental realization of a low-loss nano-scale Si hybrid plasmonic waveguide
- 2011
-
Ingår i: Optics InfoBase Conference Papers. - Washington : Optical Society of America. - 9781557529060
-
Konferensbidrag (refereegranskat)abstract
- A novel hybrid plasmonic waveguide with nano-scale confinement, consisting of a metal layer separated from a SOI nano-rib by a thin silica layer has been realized. The loss of 0.01dB/μm allows for ultra-high density photonic integration.
|
|
| 32. |
- Yu, Longhai, et al.
(författare)
-
Thermally tunable silicon photonic microdisk resonator with transparent graphene nanoheaters
- 2016
-
Ingår i: Optica. - : Optical Society of America. - 2334-2536. ; 3:2, s. 159-166
-
Tidskriftsartikel (refereegranskat)abstract
- Efficient tunable photonic integrated devices are important for the realization of reconfigurable photonic systems. Thermal tuning is a convenient and effective approach, and silicon's large heat conductivity, thermo-optical coefficient, and CMOS fabrication compatibility make it a good candidate material for tunable optical microcavities, which are versatile elements in low-cost, large-scale photonic integrated circuits. Metal heaters are traditionally used for tuning, and a thick SiO2 upper-cladding layer is usually needed to prevent light absorption by the metal since that could reduce response speed and heating efficiency. In this paper, we propose and experimentally demonstrate thermally tunable silicon photonic microdisk resonators by introducing transparent graphene nanoheaters, which contact the silicon core directly without any isolator layer. The theoretical and experimental results show that the transparent graphene nanoheaters improve the heating efficiency, the temporal response, and the achievable temperature in comparison with a traditional metal heater. Furthermore, the graphene nanoheater is convenient for use in ultrasmall nanophotonic integrated devices due to its single-atom thickness and excellent flexibility. Both experiments and simulations show that the transparent graphene nanoheater is a promising option for other thermally tunable photonic integrated devices such as optical filters and switches.
|
|
| 33. |
- Zhang, Jianhao, et al.
(författare)
-
High-Q side-coupled semi-2D-photonic crystal cavity
- 2016
-
Ingår i: Scientific Reports. - : Nature Publishing Group. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- High-Q semi-2D-photonic crystal cavities with a tapered edge and side-coupled bus waveguide are demonstrated. With a quadratic design, the unloaded cavity presents a theoretical ultrahigh quality factor up to 6.7 x 10(7) for the condition that there are mere 34 holes in the propagated direction, which is pretty close to the 2D and 1D counterpart. Combined with a side-coupled bus waveguide, an all-pass-type cavity with a loaded quality factor (Q) of over 2.4 x 10(4) and an extinction ratio over 10 dB are experimentally demonstrated. An experimental loaded Q up to 1.1 x 10(5) are also achieved by tuning the coupling between the cavity and the bus waveguide, which is much larger than any reported surface-mode cavity. This cavity is quite suitable for sensors, filters and especially optomechanical devices thanks to the mechanical stability of the cavity and flexibility of the bus waveguide.
|
|
| 34. |
- Zhang, Senlin, et al.
(författare)
-
Numerical analysis of an optical nanoscale particles trapping device based on a slotted nanobeam cavity
- 2016
-
Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 6
-
Tidskriftsartikel (refereegranskat)abstract
- A slotted nanobeam cavity (SNC) is utilized to trap a polystyrene (PS) particle with a radius of only 2 nm. The carefully designed SNC shows an ultrahigh Q factor of 4.5 x 10(7) while maintaining a small mode volume of 0.067(lambda/n(water))(3). Strongly enhanced optical trapping force is numerically demonstrated when the 2 nm PS particle is introduced into the central, slotted part of the SNC. In the vertical direction, the numerical calculation results show that a trapping stiffness of 0.4 pN/(nm.mW) around the equilibrium position and a trapping potential barrier of similar to 2000 k(B)T/mW can be reached. To our best knowledge, the trapping capability (trapping stiffness and trapping potential barrier) of the proposed structure significantly outperforms the theoretical results of those in previously reported work. In addition, the SNC system does not suffer from the metal induced heat issue that restricts the performance of state-of-the-art optical trapping systems involving plasmonic enhancement. Based on the proposed cavity, applications such as lab-on-a-chip platforms for nanoscale particle trapping and analysis can be expected in future.
|
|
