magnetically-actuated swing-type mems mirror pair for a reconfigurable optical interconnect

4126 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 31, NO. 24, DECEMBER 15, 2013

Magnetically-Actuated Swing-Type MEMS MirrorPair for a Reconfigurable Optical Interconnect

Chun-Wei Tsai, Hsu-Tang Chang, Shih-Hsiang Liu, and Jui-che Tsai, Member, IEEE

Abstract—Two different mirror pairs of 45◦-assembled swing-type micro-electro-mechanical systems mirrors for optical inter-connects are proposed. Magnetic beads are attached to the back ofthe mirror plate to enable magnetic actuation. The device is fabri-cated with the SOIMUMPs process developed by MEMSCAP, Inc.The magnetically-actuated micromirror provides a wide swing an-gle. The mirror swing angle is also sufficiently wide to enable finetuning and system reconfiguration. Two designs of torsion springsare employed. The full swing angles are 16.9◦ and 9.8◦ for the mir-rors in the roof-type arrangement pair and parallel-arrangementpair, respectively.

Index Terms—Magnetic actuation, magnetic beads, micro-electromechanical systems, optical interconnect, reconfiguration,45◦ mirror.

I. INTRODUCTION

O PTICAL interconnection/interconnects have been seenin/with optical communication [1], optical networks [2],

[3], optical switches, optical cross connects [4], wavelengthdivision multiplexing [5], [6], and computing systems [7]. Par-ticularly, micro-electro-mechanical systems (MEMS) technol-ogy can be used to realize these devices [8], [9]. Optical in-terconnects provide a novel solution for electrical intercon-nect problems. Compared to electrical interconnects, the ad-vantages of optical interconnects include higher bandwidth,higher density integration on a board, higher data-rate, lowercrosstalk, and lower electromagnetic interference [10]–[12].Therefore, optical interconnects, including rack-to-rack [13],board-to-board [14]–[16], chip-to-chip [17]–[19], and intra-chip [20]–[22] ones, have been targeting replacing their electri-cal counterparts. An optical interconnect module may includeelectronics chips, light sources, photodetectors, optical fibers,optical waveguides, free space, 45◦ mirrors, lens arrays, andprinted circuit boards, etc. [23] A major component is the 45◦-slanted reflecting surface or mirror that is often used to deflectlight by 90◦. Anisotropic silicon wet etching has been used tofabricate 45◦ mirrors of this kind [24], [25]; however, these

Manuscript received July 1, 2013; revised October 7, 2013; accepted Octo-ber 18, 2013. Date of publication October 31, 2013; date of current versionNovember 27, 2013. This work was supported by the National Science Councilof Taiwan under Grants NSC 100-2628-E-002-002 and NSC 101-2221-E-002-056-MY3, and the Excellent Research Projects of National Taiwan Univer-sity, 10R80919-1, AE01-01 (101R89081), and 102R89084.

The authors are with the Graduate Institute of Photonics and Optoelectron-ics and the Department of Electrical Engineering, National Taiwan University,Taipei 10617, Taiwan (e-mail: [email protected]).

Color versions of one or more of the figures in this paper are available onlineat http://ieeexplore.ieee.org.

Digital Object Identifier 10.1109/JLT.2013.2288148

mirrors are fixed, which prevents optical beam steering and op-tical fine tuning. Therefore, we have designed and fabricated45◦-assembled micromirrors with swinging ability. With theirachieved swing angles, the mirrors are capable of system fineadjustment and reconfiguration. Some preliminary results of asingle mirror of one design were reported recently [26]. Thispaper presents the comprehensive study, covering mirrors ofdifferent designs, mirror pairs of different arrangements, opticalsetup experiments, etc., and includes more details such as thedevice cross sections and assembly steps.

Different driving mechanisms can be used to fabricateMEMS-based optical interconnects. Commonly seen drivingmechanisms for MEMS mirrors include electrostatic, thermal,piezoelectric, and magnetic actuation mechanisms [27]–[34].The two main approaches to implementing magnetic actuationare using the Lorentz force [35], [36] and making part or allof the device out of a magnetic material so that an externalmagnet can be used to actuate the device [37], [38]. The latterapproach can bypass the issue of ohmic loss if a permanentmagnet, instead of an electromagnet, is used. Also, as opposedto approaches using electrostatic actuation, thermal actuation,piezoelectric actuation, and/or Lorentz force, it avoids the needto feed a current or voltage to the device, which eliminates theneed for wiring and the risk of electrically damaging the de-vice. Therefore, we have chosen to use this magnetic actuationapproach for our mirrors.

After finishing the clean room process and releasing the mir-ror, we use a nanoliter injector to dispense a droplet of magnetic-bead suspension of controlled volume over the back of themirror. This approach to attaching the magnetic material en-ables precise control of the amount and location of the magneticmaterial and enable in-situ testing while applying the material.

This paper presents two different mirror pairs of 45◦-assembled swing-type MEMS mirrors for optical interconnects.The MEMS mirror pair is actuated using a manually controlledpermanent magnet for proof of concept. The final goal is to usemotorized translation stage to carry the permanent magnets. Themotorized stage shall have the characteristic that the power canbe turned off while remaining at a fixed position, for example,KXL06100-N2-G, Suruga Seiki Co., LTD. This provides us anoptical interconnect which requires no power consumption atthe steady state, i.e. normally-off operation; the power of thestages is turned on only when optical switching or tuning isneeded. With this approach, an optical interconnect with lowelectrical power consumption can be achieved.

In our study, we have also tried actuating the mirror with anelectromagnetic coil. This actuation method requires a constantelectric current and constant power consumption even at the

0733-8724 © 2013 IEEE

TSAI et al.: MAGNETICALLY-ACTUATED SWING-TYPE MEMS MIRROR PAIR FOR A RECONFIGURABLE OPTICAL INTERCONNECT 4127

Fig. 1. 3-D schematic drawings of the mirror pairs of (a) roof-type arrange-ment and (b) parallel-type arrangement. For simplicity, buried oxide is notshown.

steady state, and does not satisfy our intended purpose. However,we still include the result of electromagnetic actuation (angleversus current) at the end of the paper for readers’ reference.

II. DESIGN AND FABRICATION

Fig. 1(a) and (b) show 3-D schematic drawings of the fully-assembled magnetically-actuated swing-type MEMS mirrorpairs of roof-type arrangement and parallel-type arrangement,respectively. Torsion springs of the mirror plates in the pair ofroof-type arrangement are longer than those in the parallel-type-arrangement pair. Each mirror includes a gold-coated torsionalmirror plate, mirror frame, and latching mechanism. The mag-netic beads are attached to the back of the mirror plate. Thedevice is fabricated using the SOIMUMPs process developedby MEMSCAP, Inc. [39], which uses silicon-on-insulator waferswith a 10-μm device layer, 1-μm buried oxide, and 400-μm han-dle substrate. At the mirror plate, a metal layer of 50-nm Cr and600-nm Au is coated on the top of the device layer to increaseoptical reflectivity. Table I shows the dimensions and param-eters of the 45◦-assembled swing-type MEMS mirror design.The mass of the mirror plate, including the metal coating, is2.311 × 10−5g. The torsion spring constant is 4.395 × 10−7

TABLE IDIMENSIONS/PARAMETERS FOR THE MICROMIRROR DESIGN

Fig. 2. Schematic cross sections (along A–A′ of the insets) (a) before and(b) after assembly. The structure details and the corresponding material/layersare shown.

and 8.789 × 10−7 N·m/rad for the mirrors in the roof-type andparallel-type arrangements, respectively. The radius of curvatureR of the mirror with metal coating is measured to be ∼20 mm.The resonance frequency is calculated as ∼1.336 and 1.889 kHzfor the mirrors in the roof-type and parallel-type arrangements,


Fig. 3. Adhesion of magnetic beads and the assembly flow.

respectively. With no applied magnetic field, a torque (τ ) of7.203 × 10−11 N·m is applied to the 45◦-slanted mirror by thegravity, and the resultant angular deflections (θ) of the mirrorsin the roof-type and parallel-type arrangements are 16.39 ×10−5 rad (9.392 × 10−3 degree) and 8.196 × 10−5 rad (4.696 ×10−3 degree), respectively, which are negligible.

Fig. 2(a) and (b) are the schematic device cross sections (alongA–A′ of the insets) before and after assembly, respectively.The structural details and the corresponding materials/layersare shown. After the clean room process, the mirror plate, mir-ror frame, and latching mechanism are released, and the chip isflipped to apply magnetic beads (3 μm diameter, Fe3O4 , MagQuCo., Ltd.) on the back of the mirror as shown in Fig. 3(a). Inthe magnetic bead application step, droplets of suspension ofthe magnetic beads (50-mg Fe3O4 /mL) are first dispensed us-ing a microprocessor-controlled injector (Nanoliter 2000) whichenables precise control of the droplet volume. The average di-ameter of the magnetic beads is 3 μm, and each magnetic beadconsists of a Fe3O4 core coated with dextran. The magneticbeads are superparamagnetic and are suspended in phosphate-buffered saline solution to form the suspension which is used inthis study. The repeatability of using the Nanoliter injector tocontrol the volume of the dispensed magnetic bead suspensionhas been evaluated. The relative standard deviation among theactual volumes dispensed in different attempts is 5.98%, 3.89%,and 3.51% when the target volume is 23 nL, 46 nL, and 69 nL,

Fig. 4. Optical microscope images of the mirror pair of roof-type arrangement:(a) front side of the unassembled device, (b) 3-D front view of a 45◦-assembledmirror, and (c) 3-D back view of a 45◦-assembled mirror.

Fig. 5. Optical microscope images of the mirror pair of parallel-type arrange-ment: (a) front side of the unassembled device, (b) 3-D front view of a 45◦-assembled mirror, and (c) 3-D back view of a 45◦-assembled mirror.

respectively. The chip is then air-dried until the solvent evapo-rates from the suspension, leaving only the magnetic beads.

Fig. 3(b)–(f) are the drawings which show the assemblyflow. The mirror frame on the left side is lifted with probes toapproximately 60 degrees [Fig. 3(c)]. The latching mechanismon the right side is also lifted with probes to approximately60 degrees [Fig. 3(d)]. The probes holding the mirror framedare lowered to 45◦ [Fig. 3(e)]. Using the probes, the latchingmechanism is slowly dropped onto the mirror frame [Fig. 3(f)].


Fig. 6. Experimental setup for measuring rotation angles under the influenceof an external permanent magnet. The magnet is moved along the x axis.

Fig. 7. Experimental results for 45◦-assembled mirror pair of roof-type ar-rangement. Each mirror has the same amount (20 droplets) of magnetic beadsuspension applied on its back. (a) Mirror rotation angles versus magnet’s posi-tion along the x axis; (b) three photos taken: (i) maximum outward angle of theleft mirror achieved at x = −10 mm (magnet’s position), (ii) minimum angleof the left mirror achieved at x = −7 mm, (iii) maximum inward angle of theleft mirror achieved at x = −3 mm. The dash lines indicate the mirror framesand the arrows to show the mirror rotation directions.

Finally, the probes on both sides are removed, and the mirrorframe and latching mechanism are interlocked.

Fig. 4(a) is an optical microscope image of the front side ofthe unassembled mirror pair of roof-type arrangement. Fig. 4(b)

Fig. 8. Experimental results for 45◦-assembled mirror pair of parallel-typearrangement. 30 and 10 droplets of magnetic bead suspension are dispensedon the left and right mirrors, respectively. (a) Mirror rotation angles versusmagnet’s position along the x axis; (b) three photos taken: (i) maximum inwardangle of the left mirror achieved at x = 1 mm, (ii) minimum angle of the leftmirror achieved at x = 4 mm, and (iii) maximum outward angle of the leftmirror achieved at x = 7 mm. The dash lines indicate the mirror frames andarrows show the mirror rotation directions.

Fig. 9. Experimental setup used to measure the rotation angles in the presenceof an external permanent magnet moving in the z direction.

and (c) shows the 3-D front and back views of the 45◦-assembledmirrors; Fig. 5(a) is an optical microscope image of the front sideof the unassembled mirror pair of parallel-type arrangement;Fig. 5(b) and (c) shows the 3-D front and back views of the45◦-assembled mirrors.

III. EXPERIMENTS AND DISCUSSION

A. Rotation Angle Versus Magnet’s Position Along x-axis

Fig. 6 shows the experimental setup used to determine theeffect of the external permanent magnet on the rotation angle.


Fig. 10. Rotation angle versus the magnet’s position along the z axis, mea-sured with different x positions of the magnet, for the mirror pair of roof-typearrangement: (a) left mirror (with 20 droplets) and (b) right mirror (with 20droplets).

The chip is mounted on a fixed holder. The magnet is first placed3 mm above the mirror pair. It is then moved along the x axis witha travel distance of 24 mm (between x = −12 mm and 12 mm,with x = 0 mm at the middle between two mirrors), and therotation angles are measured. Both the mirror pairs of roof-typearrangement and parallel-type arrangement are experimentallytested.

In an assembled device, only the mirror plate can rotate be-cause the frame is fixed by the latching mechanism. Fig. 7(a)shows the mirror rotation angles versus magnet’s position alongthe x axis of the 45◦-assembled mirror pair of roof-type ar-rangement. The mirror rotation angle is defined as the angle be-tween the mirror and frame. The inset shows the z-componentmagnetic flux density at each mirror versus magnet’s positionalong the x axis. Each mirror has the same amount (20 droplets,46 nL) of magnetic bead suspension applied on its back. Theoutward angles of the left and right mirrors reach the max-ima at x = −10 and x = 9 mm, respectively. The maximumswing of the mirror is 16.9 degrees (12.3 degrees outward and

Fig. 11. Rotation angle versus magnet’s position along the z axis, measuredwith different x positions of the magnet, for the mirror pair of the parallel-typearrangement (a) left mirror (with 30 droplets) and (b) right mirror (with 10droplets).

4.6 degrees inward for the left mirror). Three side-view photosare taken [Fig. 7(b)]: i) maximum outward angle of the left mir-ror achieved at x = −10 mm (magnet’s position), ii) minimumangle of the left mirror achieved at x = −7 mm, iii) maximuminward angle of the left mirror achieved at x = −3 mm. Ideally,the results in Fig. 7 should exhibit symmetry. There are severalreasons why the actual experimental results deviate from theideal case. First, the permanent magnet in use is asymmetric,yielding an asymmetric distribution of magnetic flux density.Moreover, etching nonuniformity could lead to different springwidths and, therefore, different torsion spring constants for thetwo individual mirrors of the pair. Also, as mentioned in SectionII, there exists a dispensed droplet volume variation of 3.89%(relative standard deviation) from one attempt to another, re-sulting in slightly different amounts of magnetic material on thetwo mirrors.

Fig. 8(a) shows the experimental results for the 45◦-assembledmirror pair of parallel-type arrangement. 30 and 10 droplets ofmagnetic bead suspension are dispensed on the left and rightmirrors, respectively. As expected, the rotation angle increases


Fig. 12. (a) Experimental setup for demonstrating the concept of a reconfig-urable optical interconnect using the mirror pair of reverse-roof-type arrange-ment. Photos showing the light paths at the (b) left mirror and (c) right mirrorare also included.

Fig. 13. Trace of the light spot on a screen of the reflected laser beam fromthe mirror pair of reverse-roof-type arrangement in Fig. 12(a).

with the amount of magnetic beads attached to the device. Themaximum outward angles of the left and right mirrors occur atx = 7 and x = 9 mm, respectively. The full swing of the mirrorwith 30 droplets (69 nL) is 9.8 degrees (5.8 degrees outwardand 4 degrees inward). Three photos are taken [Fig. 8(b)]: i)maximum inward angle of the left mirror achieved at x = 1 mm,ii) minimum angle of the left mirror achieved at x = 4 mm, andiii) maximum outward angle of the left mirror achieved at x =7 mm.

The mirror’s torsion spring length in the mirror pair of roof-type arrangement is longer than that in the mirror pair of parallel-type arrangement. Therefore, the torsion spring constant of themirror in the roof-type arrangement pair is smaller, i.e., thespring is more compliant. This results in larger rotation anglesof the mirror pair of roof-type arrangement.

Fig. 14. (a) Experimental setup for demonstrating the concept of a reconfig-urable optical interconnect using the mirror pair of parallel-type arrangement.Photos showing the light paths at the (b) left mirror and (c) right mirror are alsoincluded.

Fig. 15. Trace of the light spot on a screen of the reflected laser beam fromthe mirror pair of parallel-type arrangement in Fig. 14(a).

B. Rotation Angle Versus Magnet’s Position Along z-axis

Fig. 9 is the experimental setup used to measure the rotationangles in the presence of an external permanent magnet movingin the z direction. As the magnet is moved along the z axis witha travel distance of 10 mm, the rotation angles are measured.The experimental data of the left mirror in the pair of roof-typearrangement are obtained with the magnet at the three differentx positions in Fig. 7(b), x =−10,−7, and−3 mm, while the leftmirror in the pair of parallel-type arrangement is characterizedwith the magnet at the x positions in Fig. 8(b), x = 1, 4, and7 mm. The right mirrors in both arrangements are tested whenthe magnet is placed at x = 3, 6, and 9 mm, respectively.

Fig. 10 demonstrates the mirror rotation angle versus themagnet’s position along the z axis, measured with different xpositions of the magnet, for the mirror pair of roof-type ar-rangement. Fig. 10(a) and (b) shows the experimental resultsfor the left and right mirror, respectively. Fig. 11 demonstratesthe mirror rotation angle versus magnet’s position along the z


TABLE IIPERFORMANCE COMPARISON BETWEEN THE PROPOSED DEVICE AND OTHER REPORTED DEVICES

Fig. 16. Rotation angle versus applied current on the electromagnet for the45◦-assembled mirror pair of roof-type arrangement with the electromagnetlocated at x = 12 mm and 3 mm above the mirror pair. Each mirror has thesame amount (20 droplets) of magnetic bead suspension applied on its back.

axis, again, measured with different x positions of the magnet,for the mirror pair of the parallel-type arrangement. Fig. 11(a)and (b) shows the experimental results for the left and rightmirrors, respectively. Each inset in Fig. 10 and Fig 11 showsthe z-component magnetic flux density (right at the mirror ofinterest) versus magnet’s position along the z axis.

Fig. 17. Rotation angle versus applied current on the electromagnet for the45◦-assembled mirror pair of parallel-type arrangement with the electromagnetlocated at x = 12 mm and 3 mm above the mirror pair. 30 and 10 droplets ofmagnetic bead suspension are dispensed on the two mirrors, respectively.

C. Measurement of the Shift of the Reflected Laser Spot

Fig. 12(a) is the experimental setup for demonstrating theconcept of a reconfigurable optical interconnect using the mirrorpair of reverse-roof-type arrangement. With this arrangement,the input and output fibers, if any, can be parallel to each other


and placed at the same side, making the packaging process eas-ier. Currently, the experiments are performed without incorpo-rating fibers; instead, a free-space laser beam is used. Fig. 12(b)and (c) are photos showing the light paths at left and rightmirror, respectively. As shown in the results of Section III.-Aand III-B, it is almost impossible to use only one magnet toachieve the ideal condition for an optical interconnect with theconfiguration shown in Fig. 12(a) – both mirrors should alwaysrotate by the same amount. Therefore, in study of this Section(III.-C) we use two external permanent magnets to accomplishindependent control over each mirror. This way, the output beamcan be kept parallel to the input beam through always rotatingboth mirrors by the same amount.

To demonstrate the beam steering ability of the mirror pair ofthis reverse-roof-type arrangement, an input HeNe laser beamis reflected by the left and then the right mirrors, and the lightspot of the reflected beam on a screen is traced. Fig. 13 showsthe trace of the light spot.

Fig. 14(a) is the experimental setup for demonstrating theconcept of a reconfigurable optical interconnect using the mir-ror pair of parallel-type arrangement. Ideally, the metal coatingof the left mirror in Fig. 14(a) should be on the backside wherethe light is reflected. However, currently we use the standard Audeposition step offered in the SOIMUMPs process to apply themetal coating, and it is not possible to deposit Au on the back-side during the SOIMUMPs run. Therefore, the experiments areperformed with the surface in use uncoated. Fig. 14(b) and (c)are photos showing the light paths at the left and right mirrors,respectively. Again, in this experiment, we use two external per-manent magnets to accomplish independent control over eachmirror. An optical signal is reflected twice and then transmittedthrough the through-Si hole of the substrate. The optical pathforms a Z–shape. As in the experiment of Fig. 12(a), the outputbeam is kept parallel to the input beam through always rotatingboth mirrors by the same amount.

Fig. 15 shows the trace of the light spot. With either setup andsome modifications to the system/device parameters (e.g. sepa-ration between mirrors), if necessary, our mirror swing anglesare sufficient not only to allow fine tuning, e.g., fine tuning thecoupled power into an output fiber, but also to enable systemreconfiguration, e.g., switching the light signal from one outputport to another. With the mirror’s radius of curvature measuredto be ∼ 20 mm, we expect, by estimate, an insertion loss of5 dB caused by this curvature when incorporating fibers into thesetups.

IV. CONCLUSION

This study demonstrates two MEMS mirror pairs for opticalinterconnects, each consisting of two 45◦-assembled swing-typemirrors that can be magnetically actuated. The mirror has mag-netic beads attached to its back side, and its rotation angle iscontrolled by a sliding permanent magnet. The actuation methoddoes not require wiring and avoids possible electrical damageto the device.

The mirror’s torsion spring length in the mirror pair of roof-type arrangement is longer than that in the mirror pair of parallel-

type arrangement. Therefore, the torsion spring constant of themirror in the roof-type arrangement pair is smaller, i.e., thespring is more compliant. This results in larger rotation angles ofthe mirror pair of roof-type arrangement. The full swing anglesare 16.9◦ and 9.8◦ for the mirrors in the roof-type arrangementpair and parallel-arrangement pair, respectively. There anglesare adequate for performing both fine tuning and system recon-figuration. Table II summarizes the performance comparisonbetween the proposed device in this paper and other reportedMEMS mirrors/actuators.

Furthermore, both the mirror pairs of roof-type and parallel-type arrangements have also been experimentally tested usingelectromagnets. However, the magnetic field of an electromag-net is produced by an electric current. The magnetic field existsonly when the current is turned on; that is to say, there is con-stant power consumption even in the steady state. On the con-trary, steady-state electrical power consumption can be avoidedwith our proposed approach where permanent magnets areused.

For readers’ reference, we still include the results obtainedfrom electromagnetic actuation. Fig. 16 shows the mirror rota-tion angle versus applied current for the 45◦-assembled mirrorpair of roof-type arrangement with the electromagnet locatedat x = 12 mm and 3 mm above the mirror pair. Each mirrorhas the same amount (20 droplets) of magnetic bead suspen-sion applied on its back. Fig. 17 shows the mirror rotation angleversus applied current for the mirror pair of parallel-type ar-rangement, again with the electromagnet located at x = 12 mmand 3 mm above the mirror pair. 30 and 10 droplets of magneticbead suspension are dispensed on the two mirrors, respectively.The power consumption at 15 A is 300 W, which is just too highfor practical application.

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Chun-Wei Tsai received the B.S. degree in electrical engineering from FengChia University, Taichung, Taiwan, in 2002, and the M.S. degree from theGraduate Institute of Electro-Optical Science and Technology, National TaiwanNormal University, Taipei, Taiwan, in 2004. Currently, he is working toward thePh.D. degree at the Graduate Institute of Photonics and Optoelectronics, Na-tional Taiwan University, Taipei, Taiwan. His research interests include opticalmicroelectromechanical systems (MEMS), MEMS technologies, optical fibercommunication, and MEMS actuators/sensors.

Hsu-Tang Chang received the B.S. degree in the Department of Bio-lndustrialMechatronics Engineering from National Taiwan University (NTU), Taipei,Taiwan, in 2011. He received the M.S. degree from the Graduate Instituteof Photonics and Optoelectronics at NTU, Taipei, in 2013. His researchinterests include optical MEMS technologies, MEMS actuator, and opticalcommunication.

Shih-Hsiang Liu received the B.S. degree in nano science and engineering fromNational Chiao Tung University, Hsinchu, Taiwan, in 2012. Since 2012, he hasbeen working toward the M.S. degree in the Graduate Institute of Photonicsand Optoelectronics at National Taiwan University, Taipei, Taiwan. His currentresearch interests include optical MEMS, optical system design and 3D display.

Jui-che Tsai (M’09) received the B.S. degree in electrical engineering fromNational Taiwan University (NTU), Taipei, Taiwan, in 1997, the M.S. degreein electro-optical engineering from the Graduate Institute of Electro-OpticalEngineering [currently named Graduate Institute of Photonics and Optoelec-tronics], NTU, in 1999, and the Ph.D. degree in electrical engineering from theUniversity of California, Los Angeles, USA, in 2005.

From 1999 to 2001, he was a Second Lieutenant in the military. Before join-ing the faculty of NTU, he was a Postdoctoral Researcher with the Departmentof Electrical Engineering and Computer Sciences and the Berkeley Sensor andActuator Center, University of California, Berkeley. He is currently an Asso-ciate Professor with the Graduate Institute of Photonics and Optoelectronics andthe Department of Electrical Engineering, National Taiwan University, Taipei,Taiwan. His research interests include optical microelectromechanical systems(MEMS), MEMS technologies, optical fiber communication, and biophotonics.

magnetically-actuated swing-type mems mirror pair for a reconfigurable optical interconnect

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