Reconfigurable OADM and OXC designed by a new optical switch

a

t.opticalacity ingM andin in-comess andlity of

ulti-igh-such

p aegen-to

Optical Fiber Technology 10 (2004) 187–200

www.elsevier.com/locate/yofte

Reconfigurable OADM and OXC designedby a new optical switch

Yu-Lung Lo,∗ Hsi-Chang Chow, and Chih-Yen Chiang

Department of Mechanical Engineering, National Cheng Kung University, Tainan, Taiwan, Republic of Chin

Received 6 September 2002; revised 29 October 2003

Abstract

A new dynamically selective optical add/drop multiplexer (OADM) and optical cross-connec(OXC) configuration for dense wavelength division multiplexed (DWDM) networks are proposedThe selective devices are based on fiber Bragg gratings (FBGs), single-sided micro-mirrorswitches (OSWs), and optical circulators (OCs). They are flexible, expandable, and high capDWDM networks if the basic units are cascaded in series. In this paper, fiber collimators in couplinare analyzed in order to characterize the insertion loss and output power equalization in OADOXC. “Off-the-shelf” DWDM communication products are used for analysis; as a result, the masertion loss in the system comes from circulators while the maximum insertion loss deviationmainly from FBGs and micro-mirrors. As compared to the other existing reconfigurable OADMOXCs, the number of mirrors in the optical switch could be dramatically reduced. The reliabioptical switch operation, therefore, can be enhanced. 2003 Elsevier Inc. All rights reserved.

1. Introduction

Optical transport systems are rapidly evolving into dense wavelength-division mplexing (DWDM) networks. Significant effort has been devoted to the design of hcapacity, flexible, reliable, and transparent multi-wavelength optical networks. Oneimportantfunction is to use optical add/drop multiplexers (OADMs) to add and drosubset of wavelengths from the transmission system without full opto-electronic reration. Another important function is theability to use optical cross-connects (OXC)select, interchange, and rearrange DWDM channels in the spatial domain [1].

* Corresponding author.E-mail address:[email protected] (Y.-L. Lo).

1068-5200/$ – see front matter 2003 Elsevier Inc. All rights reserved.doi:10.1016/j.yofte.2003.12.001

188 Y.-L. Lo et al. / Optical Fiber Technology 10 (2004) 187–200

amagrat-

withrating/drople

] pro-r fiber

iondctlittersuble-roptches

dvery

chan-ultiple

h pro-rors inign isn.n.

hilesystemh asaxialx-law1nses

mplexto ando

Some new configurations are proposed in the field of OADM and OXC. Okayet al. [2] proposed an add/drop node that consists of pairs of tunable and staticings for the realization of dynamic wavelength selection. Wavelength switchingsmall wavelength tuning and maximum wavelength channel density for a given gbandwidth is attained. Liaw et al. [1] proposed two reconfigurable wavelength addmultiplexer (WADM) and optical cross-connect(OXC) devices based on strain-tunabfiber Bragg gratings (ST-FBGs) and two three-port optical circulators. Chen et al. [3posed a fixed and reconfigurable MZ-FBG-based OADMs which uses Mach–ZehndeBragg grating-based devices with associatedoptical switches to construct large-dimensOADMs without the need for wavelength demultiplexers and multiplexers at the drop anadd ports. Park et al. [4] proposed a multi-wavelength bi-directional optical cross-conne(B-OXC) structure based on fiber Bragg gratings (FBGs) and polarization beam sp(PBSs). Recently, Pu et al. [5] proposed a client-configurable OADM that uses dosided mirrors of micro-electro-mechanical system (MEMS) matrix switches to add/dsignals. However, semiconductor fabrication of double-sided mirrors in MEMS swiis not standard, and the switch is thus more complicated with a lower yield.

In this paper, a new dynamically selectiveoptical add/drop multiplexer (OADM) anoptical cross-connect (OXC) configuration for DWDM networks are proposed. Esingle-stage OADM and OXC device can add/drop or interchange three DWDMnels simultaneously. The channel number could be expanded easily by cascading msingle-stage OADMs or OXCs in series. It is concluded that the advantage of sucposed devices is the dramatic minimizing of the number of actuated single-sided miran optical switch. Although the signal equalization in the output port of the new desnot good, using a collimator with the longer working distance can minimize the deviatioThe post signal process using a gain equalizer also can solve the signal equalizatio

2. Light coupling between single-mode fibers with collimators

The insertion loss and the flatness of the output powers in OADM and OXC wadding/dropping or cross-connecting signals can be characterized as the couplingconfiguration between two single-mode fibers with collimators [6] in an optical switcshown in Fig. 1. For the sake of simplicity, only the coupling loss associated with theseparation is considered in the MEMS design. In Fig. 1,n represents the refractive indein the center of a collimator,g is defined as the expression of the assumed squaredependence of the refractive index,n1 andn2 are the refractive indices in dielectricsand 2, andzw is the final waist location relative to the second lens surface. All fiber-lefor analysis are fused to a single-mode fiber, thusl0 = 0.

The analysis presented here utilizes the ray matrix transformation of the cobeam parameter after Kogelnik [7] and parallels the square-law analysis of KishimoKoyama [6]. The on-axis coupling efficiency,η, is determined from the overlap of the twGaussian beams atz and is given by

η = 4

w21(z)w2

2(z){[ 1

2 + 12

]2 + [(n2πλ

)( 1R (z)

+ 1R (z)

)]2} , (1)

w1(z) w2(z) 1 2

Y.-L. Lo et al. / Optical Fiber Technology 10 (2004) 187–200 189

on

dm.atedut port

g ofdgth is

Fig. 1. Arrangement of fiber pair lenses.

wherewi(z) is the beam radius atz, given by

wi(z) = w0i

{1+

[(z − zw)λ

πnw20i

]2}1/2

, (2)

whereZw(l0 = 0) is the position of the beam waist which can be expressed as

Zw =n2

[1− (

a0ng

)2]sin(gl)cos(gl)

ng[sin2(gl) + (

a0ng

)2 cos2(gl)] , (3)

wherea0 = λ/πω20. The parameterRi(z) in Eq. (1) is the beam radius of curvature atz,

given by

Ri(z) = (z − zw)

{1+

[πnw2

0i

(z − zw)λ

]2}

, (4)

andi = 1 and 2. Whilen1 = n2 = 1 in the free-space, the “off-the-shelf” communicatifibers modified by chemical vapor deposition (MCVD) as the collimator (g = 1.61 mm−1)[8] is chosen. The refractive index,n, and the length,l, of the collimator lens are 1.58 an1270 µm, respectively. The beam waist,w0, at the end face of a single-mode fiber is 4.6 µConsequently, according to Eq. (1), the coupling loss associated with axial separationλ = 1.55 µm is illustrated in Fig. 2 where the smallest coupling loss is 0.001 dB when thaxial separation is at 3400 µm. The analyticalresults, illustrated in Fig. 2, will be appliein Section 3 to characterize the insertion loss and the signal equalization of the outpin the proposed OADM and OXC.

3. New reconfigurable OADM devices based on OSWs, OCs, and FBGs

A basic and well-known architecture of an OADM is shown in Fig. 3, consistinan FBG and two optical circulators (OCs). At first,N multiplexed wavelengths are leto the FBG through the circulator. The filtered signal related to the Bragg wavelen


els aresed onleand

edice in

urable-port-

U-onding

3)

ignaladd

Fig. 2. Coupling loss associated with the axial separation between collimators.

Fig. 3. Basic OADM architecture using a FBG and two circulators.

reflected and returns through the circulator to the drop port. The remaining channcoupled with the added channel and then continue their forward propagation. Bathis, we introduce the configurations and operating principles of the new reconfigurabOADM and OXC devices. Additionally, the paper will discuss the signal insertion lossthe power equalization in ports following the coupling loss in collimators as introducin Section 2. Furthermore, we also propose a modified reconfigurable OADM devwhich the insertion loss and the signal equalization are partially improved.

3.1. One reconfigurable OADM unit (three-channel add/drop)

Figure 4 shows the schematic diagram of the proposed wavelength reconfigOADM based on Fig. 3. The proposed reconfigurable OADM consists of two threeoptical circulators (OCs), one modified 4× 4 micro-optical switch (OSW), eight collimators, and three FBGs. The central reflecting wavelengthλi of the FBGi is designed tomatch the WDM-channel-signalλi . Each central wavelength of the FBG should meet ITWDM standards, and its passband width should be large enough to cover the correspchannel signal with high reflectivity.

In Fig. 4, for instance, when mirror 1 (M1) is down, and mirror 2 (M2) and mirror 3 (Mare up in the optical switch, the launched channel signalλ1 is reflected by FBG1 and thendropped from the drop port of the optical circulator 1 (OC1). Subsequently, a new sλ′ with the same wavelength ofλ1 can be added to the FBG-based OADM through the
1


,

gby

sup type-sided

, therts areould

, and

torsd)9 dB.The2. For

e

Fig. 4. One reconfigurable OADM unit (three-channel add/drop).

port of the OC2 and then reflected back by FBG1. λ2 andλ3 are reflected by M2 and M3respectively. They then pass through the output port of the OC2 withλ′

1. Similarly, twoor three signals can be added/dropped from the same unit configuration only by switchindown the associated mirrors. Consequently, channel selectivity can be performed easilyswitching the micro-mirrors in the modified 4× 4 optical switch. Also, all micro-mirrorare single-sided and the mechanism to switch the signals is through the use of a pop-of actuation. It turns out that the standard manufacturing process in MEMS for singlemirrors which are switched using a pop-up could be easily realized.

3.2. Optimum design in light coupling in devices

Considering the OADM unit based on an MEMS architecture, as shown in Fig. 4insertion loss and the insertion loss deviation among signals in the drop/output poassociated with the analytical results in light coupling from Fig. 2. The signal loss cbe attributed to the light coupling loss in collimators, reflection loss in micro-mirrorsinsertion loss in FBGs (in-band and out-of-band) and circulators.

For analysis, “off-the-shelf” DWDM communication products for FBGs and circulaare chosen; therefore, the maximum transmission (out-of-band) and reflection (in-banlosses in FBGs are both 0.2 dB while the maximum insertion loss in circulators is 0.In MEMS manufacturing, the reflection loss of micro-mirrors is around 0.3 dB [9].coupling loss in collimators is related to the axial separation as described in Sectionexample, Fig. 5 illustrates all the loss possibilities in the OADM device while addingλ′

1.The maximum insertion loss is primarily from the circulator loss (0.9 + 0.9 = 1.8 dB).It has been calculated that when the distanced is 1000 µm, the minimum deviation in th


refore,everyertion

rts forin the

Fig. 5. All causes of the maximum insertion loss by addingλ1.

drop/output ports due to the axial separation of two collimators can be achieved. Theall calculations are based on this conclusion. Table 1 shows the insertion loss foradd/drop case, when the maximum insertion loss is 4.0950 dB and the minimum insloss 2.0874 dB. The corresponding insertion loss deviation in the drop/output poevery add/drop case is shown in Table 2. The maximum insertion loss deviationdrop/output ports is 1.1088 dB when add/drop isλ1 andλ3. The minimum deviation in thedrop/output ports is zero while there is only add/dropλ2 or no add/drop signal.


48

748

B;

d the

el pos-tancer elim-

posedted inunitionectionrable

ertionimumeveryt portsis

Table 1Insertion loss for every add/drop case

Add/drop signal No λ1 λ2 λ3 λ1λ2 λ2λ3 λ1λ3 λ1λ2λ3

Insertion Drop λ1:2.0874 λ2:2.7088 λ3:4.0950 λ1:2.0874 λ2:2.7088 λ1:2.0874 λ1:2.0874loss (dB) port λ2:2.5748 λ3:3.1962 λ3:3.1962 λ2:2.5748

λ3:3.0622

Output λ1:2.7544 λ′1:4.0950 λ1:2.7088 λ1:3.0912 λ′

1:3.1962 λ1:2.6418 λ′1:3.1962 λ′

1:3.0622

port λ2:2.7544 λ2:3.0912 λ′2:2.7088 λ2:3.0912 λ′

2:2.7088 λ′2:2.5747 λ2:2.6418 λ′

2:2.5747

λ3:2.7544 λ3:3.0912 λ3:2.7088 λ′3:2.0874 λ3:2.6418 λ′

3:2.0874 λ′3:2.0874 λ′

3:2.0874

Table 2Insertion loss deviation for every add/drop case


Deviation (dB) Drop port 0 0 0 0 0.4874 0.4874 1.1088 0.97

Output port 0 1.0038 0 1.0038 0.5544 0.5544 1.1088 0.9

In Table 2, the maximum insertion loss deviation is 1.1088 dB for add/dropλ1 andλ3.In this case, insertion losses ofλ1 andλ3 in the drop/output port are 2.0872 and 3.1962 dtherefore, the deviation betweenλ1 andλ3 is found as 3.1962− 2.0874= 1.1088 dB. Themain causes of the deviation could be attributed to the insertion loss in FBGs anreflection loss in micro-mirrors.

The problems of insertionloss and deviation canbe solved partially by designing thcollimators in which the larger range of the working distance is required to cover alsible optical paths in the switch. Less dB deviation in the range of the working dismeans less insertion loss deviation. The modified reconfigurable OADM designed foinating the insertion loss and deviation will be further introduced in Section 3.3.

3.3. Modified reconfigurable OADM devices based on OSWs, OCs, and FBGs

For ameliorating the performances of the insertion loss and deviation in the proreconfigurable OADM configuration as described above, the modification is illustraFig. 6. We divide the original OADM device into three units, and every individualdevice contains a modified 2×2 optical switch. If we use the same DWDM communicatproducts (FBGs and circulators) as referred to in Section 3.2 and also 0.3 dB reflloss in micro-mirrors, the minimum insertion loss deviation in the modified reconfiguOADM could easily be obtained by choosing distance parameter,d , as 1700 µm, whichis just half the optimum axial separation as illustrated in Fig. 2. Table 3 shows insloss for every add/drop case. The maximum insertion loss is 3.2062 dB and the mininsertion loss is 2.0020 dB. The corresponding deviation in the drop/out ports foradd/drop case is also shown in Table 4. The maximum deviation in the drop/outpuis 1.0062 dB when add/dropλ1 andλ3. The minimum deviation in the drop/output portszero when it is only add/dropλ2 or no add/drop signal.


s com-difiedss be-2devi-

Fig. 6. Modified reconfigurable OADM devices based on OSWs, OCs, and FBGs.

As a consequence, the insertion loss and the deviation are all partially improved apared to the original OADM. The causes of transmission loss in the original and moOADM are nearly the same; nevertheless, the modified one has lower coupling lotween collimators since the axial separation is all designed optimally in the modified× 2optical switch. Even thought the modified one can reduce the insertion loss and the


83

083

ntos in the

e con-

ne to

As a

Table 3Insertion loss of every add/drop case for the modified OADM


Insertion Drop λ1:2.0020 λ2:2.6041 λ3:3.2061 λ1:2.0020 λ2:2.6041 λ1:2.0020 λ1:2.0020loss (dB) port λ2:2.4061 λ3:3.0082 λ3:3.0082 λ2:2.4061

λ3:2.8103

Output λ1:2.4031 λ′1:3.2062 λ1:2.6041 λ1:2.6041 λ′

1:3.0082 λ1:2.5051 λ′1:3.0082 λ′

1:2.8103

port λ2:2.4031 λ2:2.6041 λ′2:2.6041 λ2:2.6041 λ′

2:2.6041 λ′2:2.4061 λ2:2.5051 λ′

2:2.4061

λ3:2.4031 λ3:2.6041 λ3:2.6041 λ′3:2.0020 λ3:2.5051 λ′

3:2.0020 λ′3:2.0020 λ′

3:2.0020

Table 4Insertion loss deviation of every add/drop case for the modified OADM


Deviation (dB) Drop port 0 0 0 0 0.4041 0.4041 1.0062 0.80

Output port 0 0.6021 0 0.6021 0.5031 0.5031 1.0062 0.8

ation, it is difficult to integrate the multiple OADMs since the main unit is divided ithree sections and the total size of the device increases. This is one of disadvantagemodified OADM.

3.4. Multiple OADM units (multiple-channel add/drop) cascading in series

Figure 7 shows a schematic diagram of two OADM units cascading in series. Thfiguration consists of two three-port optical circulators (OCs), two 4× 4 micro-opticalswitches (OSWs), sixteen collimators, and six FBGs. This device could add/drop osix optical signals. For instance, if we want to drop all signals (λ1, λ2, λ3, λ4, λ5, andλ6),all corresponding mirrors (M1–M6) are directed downwards (as shown in Fig. 7).

Fig. 7. Two OADM units (six-channel) cascading in series.


add

hein the

g. 6,strate5,nc.)onfig-rable

ut 1,rtion

in-MSt 2,MS

trans-s weretween.2 dB.

result, the launched channel signals (λ1–λ6) are all reflected by the FBG1–FBG6 and thendropped from port 3 of the OC1. Meanwhile, the six channel signals ofλ′

1–λ′6 with the same

wavelength ofλ1–λ6 can be added into the OADM device via port 1 of the OC2. Thechannel signalsλ′

i (1 � i � 6), therefore, are all reflected by matching FBGi (1 � i � 6)and continue propagating forward. Finally, all signals pass through the output port of tOC2. Similarly, we can establish multiple units cascading in series for more signalsprocess.

4. Experimental setup and results

According to the modified reconfigurable OADM configuration as illustrated in Ficurrent “off-the-shelf” communication components could be easily used to demonour new design. In the experiment, three 2×2 MEMS switches (Model MS-22-15-N-2-1.DiCon Inc.), two three-port circulators (Model KSCR-A-1550-03-250S-N, Broptics Iand three FBGs (Broptics Inc.) were integrated for the prototype of the modified recurable OADM as shown in Fig. 6. The schematic prototype of a modified reconfiguOADM device is shown in Fig. 8.

The insertion loss of a MEMS switch (OSW1) was 0.46 dB from input 1 to outp0.42 dB from input 2 to output 2, and 0.17 dB from input 1 to output 2. The inseloss of a MEMS switch (OSW2) was 0.53 dB from input 1 to output 1, 0.5 dB fromput 2 to output 2, and 0.66 dB from input 1 to output 2. The insertion loss of a MEswitch (OSW3) was 0.3 dB from input 1 to output 1, 0.34 dB from input 2 to outpuand 0.15 dB from input 1 to output 2. It was found that the insertion loss for a MEswitch for different cases varied a lot. About the three-port circulator, the maximummission insertion loss was around 0.47 dB. The central wavelengths of three FBG1549.34, 1550.49, and 1551.68 nm, respectively. The reflectivity of the FBGs was be99.84 and 99.93%. The maximum reflection insertion loss of the FBGs was around 0

Fig. 8. Prototype of a reconfigurable optical add/drop multiplexer.


tion in

ngthsof thetical

wn isis

Broadband light source from an ASE source in EDFA was used for the demonstrathe modified reconfigurable OADM.

When the micro-mirrors in three OSWs were all switched off, three Bragg wavelereflected back from FBGs were all dropped to the drop port. The optical spectrumdropped channel signal with three OSW’s mirror down is illustrated in Fig. 9. The opspectrum of the dropped channel signal with two (OSW1 and OSW2) mirrors doillustrated in Fig. 10. Therefore, the feasibility of the modified reconfigurable OADMproved by Figs. 9 and 10.

Fig. 9. Optical spectrum of the dropped channel with three OSW’s mirrors down.

Fig. 10. Optical spectrum of the dropped channel with two OSW’s mirrors down.


rans-n 4,], the

tical

r linkree-three

y thedingng tonot

n withCs,, andse-

ype of].

asedp and

Fig. 11. One OXC unit.

5. Novel OXC devices based on OSWs, OCs, and FBGs

Liaw [1] proposed simple OXC devices that are unidirectional and bidirectional, tmission and reflective type of 2× 2 unit OXC. Based on the switch presented in Sectioa new OXC is introduced in this section. As compared to the one proposed by Liaw [1number of the actuated micro-mirror is dramatically eliminated. The reliability of opswitch operation, therefore, can be enhanced.

Figure 11 shows the basic configuration of a novel OXC device with upper fibe(input 1 to output 1) and lower fiber link (input 2 to output 2), consisting of two thport OCs, eight collimators, one OSW with three single-sided micro-mirrors, andFBGs. Any pair of the input channel signals (λj andλ′

j , 1� j � 3) in the OXC will cross-connect to the other fiber link from I1 to O2 and from I2 to O1 if they are reflected bcorresponding FBGj inside the FBG chains. In this case, the micro-mirrors corresponFBGj are all down. Similarly, any pair of the input channel signals not correspondiFBGj (λi andλ′

i , 1� i � 3) or when the micro-mirrors are up, the input signals willcross-connect.

Figure 12 shows the two OXCs cascading in series. The cascading constructioupper fiber link (I1 to O1) and lower fiber link (I2 to O2) consists of two three-port Osixteen collimators, two OSWs with three single-sided micro-mirrors on each onesix FBGs. Furthermore,N -channel OXC devices also could be realized in multipleries. Furthermore, unidirectional and bi-directional, and transmission and reflective tmultiple-channel OXC could be easily achieved by rearranging the circulator ports [1

6. Conclusions and discussions

A new optical switch designed for a reconfigurable OADM and OXC is proposed. Bon OSWs, OCs, and FBGs, each unit of the OADM and OXC device can add/dro


l sep-ced to

paredcolli-l pathson loss

small-ries;ls in-

ationDM

ratingto a

ad-OC.

Fig. 12. Two OXC units cascading in series.

interchange three DWDM channels simultaneously. In the modified OADM, the axiaaration of two collimators is reduced; therefore, the maximum insertion loss is redu0.8888 dB, and the maximum insertion loss deviation is reduced to 0.1062 dB as comto the original. Insertion loss and deviation problems could be solved by designingmators where a larger working distance range is required to cover all possible opticain the switch. Less dB deviation in the working distance range means less the insertiand deviation.

The system is based on devices with optical switches and FBGs to constructdimensional OADMs and OXCs. We can connect multiple OADM or OXC units in sethus, the number of dynamical DWDM channels will rise. As the number of signacrease, OADMs and OXCs may find more important applications in a cascade formand are of better use in DWDM systems and networks. Cascading will expand DWscalability and reduce the required constitutive elements. Also, the reliability in opeoptical switches for the proposed new OADM and OXC could be enhanced owingfewer number of single-sided mirrors.

Acknowledgment

The work is partially supported by Ministry of Education Program for Promoting Acemic Excellence of Universities under the grant number A-92-E-FA08-1-4, Taiwan, R


C

,

-262.

s-0)

er

, IEEE

57.(9)

torsion

M.S.rchation,sof the

searchhniquesical

Kangheng

ering,

References

[1] S.K. Liaw, K.P. Ho, C. Lin, S. Chi, Experimentalinvestigation of wavelength-tunable WADM and OXdevices using strain-tunable fiber Bragg gratings, Opt. Commun. 34 (1999) 75–80.

[2] H. Okayama, Y. Ozeki, T. Kunii, Dynamic wavelength selective add/drop node comprising tunable gratingsElectron. Lett. 33 (1997) 881–882.

[3] Y.K. Chen, C.H. Chang, Y.L. Yang, I.Y. Kuo, T.C. Liang, Mach–Zehnder fiber-grating-based fixed and reconfigurable multichannel optical add-drop multiplexers for DWDM networks, Opt. Commun. (1999) 245–

[4] S.K. Park, J.W. Park, S.R. Lee, H. Yoon, S.B. Lee, S.S.Choi, Multiwavelength bi-directional optical crosconnect using fiber Bragg grating and polarization beam splitter, IEEE Photon. Technol. Lett. 12 (200888–890.

[5] C. Pu, L.Y. Lin, E.L. Goldstein, R.W. Tkach, Client-configurable eight-channel optical add/drop multiplexusing micromachining technology, IEEE Photon. Technol. Lett. 12 (2000) 1665–1667.

[6] R. Kishimoto, M. Koyama, Coupling characteristics between single-mode fiber and square law mediumTrans. Microwave Theory Tech. MTT-30 (1982) 882–893.

[7] H. Kogelnik, Imaging of optical modes-resonatorswith internal lenses, Bell Syst. Tech. J. 44 (1965) 455–4[8] W.L. Emkey, C.A. Jack, Analysis and evaluation of graded-index fiber-lenses, J. Lightwave Technol. LT-5

(1987) 1156–1164.[9] S.S. Lee, L.S. Huang, C.J. Kim, M.C. Wu, Free-space fiber-optic switches based on MEMS vertical

mirrors, J. Lightwave Technol. 17 (1999) 7–12.

Yu-Lung Lo received B.S. degree from National Cheng Kung University in 1985, andand Ph.D. degrees in mechanical engineering from the Smart Materials and Structures ReseaCenter at the University of Maryland, College Park, in 1992 and 1995, respectively. After graduhe joined the Industrial Technology Research Institute (ITRI) in the Opto-Electronics and SystemLaboratories, working on fiber optic smart structures. He has been a member of the facultyMechanical Engineering Department at National Cheng Kung University since 1996. His reinterests are in the areas of fiber communication components, fiber-optic sensors, optical tecin precision measurements, electronic packaging, and MEMS. He has authored over 50 technpublications and filed several patents. Dr. Lo is a member of SPIE and SEM.

His-Chang Chow received B.S. degree from Department of Mechanical Engineering, TamUniversity, in 1992 and M.S. degree from Department of Mechanical Engineering, National CKung University, in 2002.

Chih-Yen Chiang received B.S. and M.S. degrees from Department of Mechanical EngineNational Cheng Kung University, in 2000 and 2002,respectively. Currently, he is in the militaryservice, Taiwan.

Documents

Reconfigurable OADM and OXC designed by a new optical switch