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ABSTRACT: In this paper, an optical switch driven by the optical force is demonstrated based on Nanoelectromechanical system (NEMS) technology. The switch consists of a Mach-Zehnder interferometer (MZI) and a ring resonator. One of the MZI arms is suspended to enable optical switching by optical force induced displacement. The optical force is introduced by injecting a control light into the ring resonator. It has a switching contrast of 16 dB and a response time of 0.2 μs, which is 10<sup>3</sup> times faster than the traditional millimeter-scaled optical switches. It has potential applications in the high speed optical-packet-switching communications and the silicon-photonic integrated circuits.
Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International; 07/2011
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J.F. Tao,
H. Cai, A.B. Yu,
W.M. Zhu,
Q.X. Zhang,
J. Wu,
K. Xu,
J.T. Lin,
G.Q. Lo,
D.L. Kwong,
A.Q. Liu
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ABSTRACT: This paper reports a silicon-based micromachined optical power detector with on-chip measurement ability. The optical power is detected by an integrated electron-tunneling displacement transducer, in which optical force is employed as the bridge between optical energy and mechanical energy transition. Compared with the traditional optical power detectors, which are based on photo absorption, the proposed optical power detector has advantages of small size (0.08 mm × 0.3 mm), low thermal noise (0.03 V/°C), large measurement range (>;20 mW) and wavelength independence. Therefore, it has potential applications as high-speed detecting element in silicon-based photonic chips and lab-on-chip systems.
Solid-State Sensors, Actuators and Microsystems Conference (TRANSDUCERS), 2011 16th International; 07/2011
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ABSTRACT: This paper reports a 3-dimensional (3D) micro-optical coupling system for improving coupling efficiency in the Littrow configured micro-electro-mechanical system (MEMS) tunable lasers. In the coupling system, an optical fiber acts as a rod lens for light convergence in the vertical plane, while a deep-etched silicon parabolic mirror confines the light in the horizontal plane. Compared with previous MEMS lasers without any light focusing or only one-directional focusing mechanism, the proposed 3D micro-optical system allows longer external cavity length and provides higher coupling efficiency. A prototype is fabricated on a SOI-wafer with an etching depth of 100 μm. The laser obtains a coupling efficiency as high as 76.5%, which is much higher than typical value of 3% - 50% in previous designs. The laser has dimensions as small as 3 mm × 3.2 mm in single-chip integration. It achieves large tuning range of 48.3 nm within 1 ms tuning speed.
Micro Electro Mechanical Systems (MEMS), 2011 IEEE 24th International Conference on; 02/2011
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ABSTRACT: In this paper, a novel platform technology for integrating radio-frequency microelectromechanical systems (RF-MEMS) and CMOS on a printed circuit board (PCB) is demonstrated. An RF-MEMS switch is constructed on top of a CMOS IC wafer. The stacked structure is subsequently transferred onto a PCB substrate (i.e., FR-4) by thermal compressive bonding, mechanical grinding, and wet removal of bulk silicon. The measurement of the fabricated RF-MEMS switch on the FR-4 substrate shows promising results. It has an insertion loss of 0.25 dB at 20 GHz and an isolation of 25 dB at 20 GHz. At the same time, the performance of CMOS is not degraded during the integration process; the drain current in the p-MOS transistor remained unchanged, whereas that in the n-MOS transistor showed a slight improvement after transfer. This technology is very useful for compact RF system on PCB material with low power consumption and high performance for wearable, wireless, and implantable device applications.
IEEE Transactions on Electron Devices 10/2008; · 2.32 Impact Factor
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ABSTRACT: In this paper, a novel platform technology for system level integration of RF-MEMS, RF passives and CMOS-IC on silicon substrate is reported. The RF passives and RF MEMS devices are fabricated on a low resistivity silicon wafer using Cu damascene process. After bonding the wafer to a CMOS wafer with recesses using benzocyclobutene (BCB) as intermediate layer and subsequently removal of bulk silicon, the RF passive components and RF MEMS devices are fully transferred onto CMOS wafer with silicon recesses underneath. The RF performance of RF-passive devices is improved significantly, e.g. the Q-factor of an inductor is improved by 174% and the resonant frequency is increased by 30%; the maximum available gain of a transformer is improved by 28%. RF-MEMS switch is sealed at wafer level and CMOS devices showed preserved device performance. This technology demonstrates the feasibility of building high performance, compact RF system on silicon substrate.
Electronic Components and Technology Conference, 2008. ECTC 2008. 58th; 06/2008
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ABSTRACT: High performance on-chip inductors fabricated using extremely thick low-stress silicon dioxide (SiO<sub>2</sub>) as the interface layer and copper damascene technology on standard CMOS silicon substrate are presented. A warpage-free low-stress SiO<sub>2</sub> layer up to 20 mum thick is deposited using a modified deposition process. The maximum quality factor of a 1.3 nH inductor has been improved by 160% (from 21 to 55) when the thickness of SiO<sub>2</sub> increases from 0.3 to 15 mum.
Electronics Letters 02/2008; · 0.96 Impact Factor
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ABSTRACT: This paper presented the design of subwavelength grating (i.e., nano-grating) for narrow-band and wide-band filter applications. The grating period can be tuned from 700 nm to 1140 nm by a rhombic-shaped thermal actuator array with a driving current of 2.7 mA, achieving a change of transmissivity by 13 dB due to the guided mode resonance. Wide-band of filtering can be obtained by use of another fixed-period grating to compensate the dispersion. Such grating design makes it practical to implement many tunable nano-optical devices.
Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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ABSTRACT: This paper presented the theoretical and experimental studies on a new mechanism of real pivot by use of a double-clamped beam. Comparison with the conventional virtual pivot formed by a cantilever beam, such real pivot provides large rotation angle and small position shift, which is key for the MEMS tunable lasers to obtain continuous wavelength tuning over a wide range. In experiment, the real pivot is able to produce a rotation angle of 4.7 degrees regardless of a depth variation of 16 % over the double-clamped beam due to fabrication error. In contrast, the virtual pivot has only 2.4 degrees in the presence of 4 % depth reduction. The real pivot design is more suitable for the MEMS tunable lasers as it is simple, symmetric, robust and allowable for single-chip integration.
Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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ABSTRACT: This paper presented the design of subwavelength grating (i.e., nano-grating) for narrow-band and wide-band filter applications. The grating period can be tuned from 700 nm to 1140 nm by a rhombic-shaped thermal actuator array with a driving current of 2.7 mA, achieving a change of transmissivity by 13 dB due to the guided mode resonance. Wide-band of filtering can be obtained by use of another fixed-period grating to compensate the dispersion. Such grating design makes it practical to implement many tunable nano-optical devices.
07/2007;
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ABSTRACT: This paper presented the theoretical and experimental studies on a new mechanism of real pivot by use of a double-clamped beam. Comparison with the conventional virtual pivot formed by a cantilever beam, such real pivot provides large rotation angle and small position shift, which is key for the MEMS tunable lasers to obtain continuous wavelength tuning over a wide range. In experiment, the real pivot is able to produce a rotation angle of 4.7 degrees regardless of a depth variation of 16% over the double-clamped beam due to fabrication error. In contrast, the virtual pivot has only 2.4 degrees in the presence of 4% depth reduction. The real pivot design is more suitable for the MEMS tunable lasers as it is simple, symmetric, robust and allowable for single-chip integration.
07/2007;
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Q.X. Zhang, A.B. Yu,
M. Tang,
H.Y. Li,
R. Yang,
E.B. Liao,
L.H. Guo,
R. Kumar,
A.Q. Liu,
G.Q. Lo,
N. Balasubramanian,
D.L. Kwong
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ABSTRACT: A thermal bonding based wafer transfer technology was developed and successfully applied to integrate RF MEMS switch and CMOS ICs on an organic substrate. The major process modules and challenges in this transfer technology are discussed. By integrated together on the new substrate, the RF-MEMS switch illustrates significantly improved performance, and the CMOS show preserved functionality. This technology demonstrates the feasibility and potential applicability of building high performance, compact RF system for wireless communication.
Solid-State Sensors, Actuators and Microsystems Conference, 2007. TRANSDUCERS 2007. International; 07/2007
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ABSTRACT: This letter presents a design of a microelectromechanical systems variable optical attenuator (VOA) that employs a pair of parabolic mirrors as the retro-reflector, which has obtained a linear relationship over a 62-dB range between the attenuation (in decibels) and the mirror rotation angle (in degrees). The insertion loss measures 0.6 dB thanks to the three-dimentional optical coupling design. The linearity comes from the simultaneous shift and defocus of the laser beam. Compared with the conventional coaxial and cross-axial VOAs, such retro-axial design has the two fibers arranged on the same side and thus facilitates the use of standard packaging formats
IEEE Photonics Technology Letters 06/2007; · 2.19 Impact Factor
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ABSTRACT: This paper presents a tuning mechanism to provide an adjustable virtual pivot for MEMS tunable lasers, which eliminates the mode hopping problem associated with conventional Littrow lasers. The key idea is to attach the two ends of the blazed grating to two separate translational actuators. The relative displacements of the actuators can be used to translate and/or rotate the blazed grating in a controllable manner. As a result, the wavelength can be continuously tuned ideally over an unlimited range through a simultaneous sweep of the grating angle and cavity length. In the experiments, a MEMS Littrow laser is fabricated by the DRIE process on the SOI wafer and is integrated onto a single chip with the size of 3 mm times 3 mm. It achieves a wide tuning range of 53.2 nm thanks to the introduction of the new tuning mechanism and a 3D optical coupling system.
Micro Electro Mechanical Systems, 2007. MEMS. IEEE 20th International Conference on; 02/2007
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ABSTRACT: This paper presents a design of thermal actuator array to generate evenly-distributed displacement by cascading an array of rhombic-shaped units. Such design is implemented to a tunable grating to tune the period by 61% and to produce a total displacement of 215 mum. Such design is scalable to the sub-wavelength level, making its very attractive to many tunable nano-photonic devices.
Micro Electro Mechanical Systems, 2007. MEMS. IEEE 20th International Conference on; 02/2007
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ABSTRACT: This paper reports a new design of MEMS variable optical attenuator (VOA) that makes use of a pair of parabolic mirrors as the retro-reflector in the horizontal plane and a normal fiber as the rod lens to focus in the vertical plane. It is advantageous over the conventional co-axial VOAs since it allows the fibers to be arranged in parallel and is thus convenient for the packaging. The parabolic mirrors improve the optical coupling and yield an insertion loss of only 1.4 dB even when only the normally-cleaved single mode fibers are used. The attenuation can go up to 63 dB when the mirror pair is rotated by 2.6 degrees. More importantly, a linear relationship is well maintained over the whole range, unlike the nonlinear relationship in many conventional VOAs. At the 20-dB level, the VOA measures a PDL of 0.2 dB and a WDL of 0.5 dB, which are superior to the typically values of 1-2 dB in the conventional VOAs.
Micro Electro Mechanical Systems, 2007. MEMS. IEEE 20th International Conference on; 02/2007
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Q.X. Zhang, A.B. Yu,
R. Yang,
H.Y. Li,
L.H. Guo,
E.B. Liao,
M. Tang,
R. Kumar,
A.Q. Liu,
G.Q. Lo,
N. Balasubramanian,
D.L. Kwong
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ABSTRACT: A novel monolithic integration of RF MEMS switch and CMOS IC on organic substrate was demonstrated. RF MEMS switch was firstly fabricated on CMOS IC wafer, and the stacked structure was subsequently transferred onto an organic substrate (i.e., FR-4). The RF-MEMS switch illustrates significantly improved performance, while integrated together, the CMOS show preserved functionality. This technology demonstrates the feasibility and potential applicability of building high performance, compact RF system for wireless communication
Electron Devices Meeting, 2006. IEDM '06. International; 01/2007
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ABSTRACT: This paper discusses fabrication aspects of photoresist sacrificial layers for fabricating metal bridges of capacitive radio frequency (RF) microelectromechanical systems (MEMS) switches. First, reflow of the photoresist layer after lithography is investigated for reducing mechanical fracture of the metal layer by smoothing the edges of the sacrificial layer. Second, the dry-etch releasing process of the structures in an O 2 plasma has been investigated by identifying suitable etching parameters. The findings in this paper reveal that the mechanical performance of the released bridges strongly depends on the etch parameters. It is shown that especially the etching power affects the mean stress and the stress gradient in the bridge, which results in buckling and deformed bridge shape for an etching power above 500 W, drastically increasing the actuation voltage and reducing the down-state capacitance. Finally, the paper presents a suitable parameter set for the release etching of capacitive MEMS metal bridges.
J. Micromech. Microeng. 01/2007; 17:2024-2030.
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ABSTRACT: This letter reports, for the first time, on RF MEMS switches integrated on flexible printed circuit boards (i.e., FR-4) using transfer technology. The devices were first processed on Si-substrate using a modified MEMS sequence and subsequently transferred onto an FR-4 substrate by thermal compressive bonding, mechanical grinding, and wet removal of silicon. The switches were demonstrated with flat metal membrane (top electrode), precisely controlled gap between the membrane and bottom electrode, low insertion loss (≤ 0.15 dB at 20 GHz), and high isolation (∼ 21 dB at 20 GHz). This technology shows the potential to monolithically integrate RF MEMS components with other RF devices on organic substrate for RF system implementation.
IEEE Electron Device Letters 08/2006; · 2.85 Impact Factor
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ABSTRACT: In this paper, a reconfigurable filter is realized using electromagnetic bandgap structures (EBG) which can be switched from bandpass to bandstop filter at the same frequency by PIN diodes. A unit model for the reconfigurable filter is derived by equivalent circuit approach and full wave electromagnetic simulation is used for extracting the values of the lumped elements. The extracted parameters show that the bandpass and bandgap effect of the EBG cells. The dispersion diagram is obtained for the structure by combining the commercial software and the Floquet's theorem. The PIN diodes are used to switch from bandpass to bandstop filter. The measurement results show that the insertion loss in bandpass filter is around 2.1 dB and the 3-dB bandwidth is around 5.2 GHz which is suitable for wideband applications. For the bandstop filter, the 20 dB rejection bandwidth is 5.3 GHz and the insertion loss in the pass band is 1.6 dB
Microwave Symposium Digest, 2006. IEEE MTT-S International; 07/2006
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ABSTRACT: Broad-band band-pass filters (BPFs) and band-stop filters (BSFs) constructed with coplanar waveguide's series open and short stubs are reported in this paper. The insertion loss is less than 1.6 dB for the BPF, and it has 60% relative 3-dB bandwidth and 77% 30-dB bandwidth. For the BSF, the 20 dB stop band is 20.5 GHz, with return loss is only 0.3 dB. The lower pass band insertion loss is less than 0.8 dB and higher pass band insertion loss is less than 1.5 dB
Microwave Symposium Digest, 2006. IEEE MTT-S International; 07/2006
