JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 25, NO. 1, JANUARY 2007 207

Field Trial of 3-WDM × 10-OCDMA × 10.71-Gb/sAsynchronous WDM/DPSK-OCDMA Using Hybrid

E/D Without FEC and Optical ThresholdingXu Wang, Senior Member, IEEE, Naoya Wada, Member, IEEE, Tetsuya Miyazaki, Member, IEEE,

Gabriella Cincotti, Senior Member, IEEE, and Ken-ichi Kitayama, Fellow, IEEE

Abstract—A cost-effective hybrid wavelength division multi-plexing (WDM), optical code division multiple access (OCDMA)scheme by sharing a single multiport encoder in a central officeand using tunable decoders in an optical network unit has beenproposed and demonstrated in a field trial. A 111-km error-freefield transmission of asynchronous 3-WDM × 10-OCDMA ×10.71 Gb/s/user has been achieved with differential phase-shiftkeying for data modulation and balanced detection. Forward-error-correction and optical-thresholding techniques were notused in the experiment.

Index Terms—Beat noise, differential phase-shift key (DPSK),fiber-optics communication, field trial, multiple-access interfer-ence (MAI), optical code division multiple access (OCDMA), wave-length division multiplexing (WDM).

I. INTRODUCTION

THE OPTICAL code division multiple access (OCDMA)technique is an attractive candidate for next-generation

broadband access networks. Fig. 1 illustrates a basic archi-tecture and working principle of an OCDMA passive opticalnetwork (PON) network. In the OCDMA-PON network, thedata are encoded into a pseudorandom optical code (OC) by theOCDMA encoder at the transmitter, and multiple users sharethe same transmission media by assigning different OCs todifferent users. At the receiver, the OCDMA decoder recog-nizes the OCs by performing a matched filtering, where theautocorrelation for the target OC produces high-level output,while the cross correlation for undesired OC produces low-level output. Finally, the original data can be recovered afterelectrical thresholding. Due to the all-optical processing forencoding/decoding, the OCDMA has the unique features ofallowing a fully asynchronous transmission with low-latencyaccess, soft capacity on demand, protocol transparency, simpli-fied network management, and increased flexibility of quality-of-service (QoS) control [1]–[3]. In addition, since the data are

Manuscript received June 30, 2006; revised September 10, 2006.X. Wang, N. Wada, and T. Miyazaki are with the National Institute of Com-

munication and Information Technology (NICT), Koganei, Tokyo 184-8795,Japan (e-mail: xwang@nict.go.jp; wada@nict.go.jp; tmiyazaki@nict.go.jp).

G. Cincotti is with the Department of Applied Electronics, University ofRoma Tre, I-00146 Rome, Italy (e-mail: g.cincotti@uniroma3.it).

K. Kitayama is with the Department of Electrical, Electronic and InformationEngineering, Osaka University, Osaka 565-0871, Japan (e-mail: kitayama@comm.eng.osaka-u.ac.jp).

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.2006.887186

encoded into pseudorandom OCs during transmission, it alsohas the potential to enhance the confidentiality in the network[4]–[6].

Recently, the coherent OCDMA technique, where encodingand decoding are based on the phase and amplitude of opticalfield instead of its intensity, is receiving much attention forits overall superior performance over incoherent OCDMA andthe development of compact and reliable en/decoders (E/Ds)[7]–[14]. In these coherent OCDMA systems, an ultrashortoptical pulse is either spectrally encoded time spread by a high-resolution phase E/D [8] or spatial-light phase modulator (PM)[9], [10] or directly time-spread encoded by a superstructuredfiber Bragg grating (SSFBG) [11]–[13] or multiport E/D with awaveguide grating configuration [14], [15].

In a multiuser coherent OCDMA network, the major noisesources are the signal-interference (SI) beat noise (coherentnoise) and the multiple-access interference (MAI) noise(incoherent noise) [3]. Basically, in a coherent OCDMAsystem with chip-rate detection, the SI beat noise dominatesthe performance, while with the data-rate detection, the MAIis dominating noise. Time gating [7]–[9], [16] and opticalthresholding (OT) [9], [10], [16]–[18] can be used to suppressthe MAI, enabling the data-rate detection. As for the SI noisemitigation, most of the previous approaches use a synchronousOCDMA, which operates under the best-case situation by aproper timing coordination in the chip or slot level to carefullyavoid the overlaps between signal and interference [7]–[11],[16]. Synchronous OCDMA can somewhat increase frequencyefficiency for transmission [16]; however, for practical accessnetwork applications, the capability of asynchronous multiuseraccess is of a key attribute. In an asynchronous OCDMA, signaland interferers are received with a random overlap; therefore,the system should be able to operate in the worst-case scenariowithout any timing coordination to guarantee asynchronousOCDMA. One effective solution is using an ultralong OC [13],[18] and E/D with a very high power contrast ratio (PCR)between auto-/cross correlation [14], [15] to suppress the inter-ference level in an asynchronous environment. Another solutionis to use forward-error-correction (FEC) techniques to enhancethe noise tolerance of the system. Multiuser coherent OCDMAat a data rate as high as 10 Gb/s has been successfully demon-strated [15], [18] by employing the SSFBG for ultralong OCprocessing, supercontinuum generation-based OT [17], AWG-type E/D with high PCR, and FEC techniques. However, these

0733-8724/$25.00 © 2007 IEEE

208 JOURNAL OF LIGHTWAVE TECHNOLOGY, VOL. 25, NO. 1, JANUARY 2007

Fig. 1. Working principle of OCDMA PON network.

Fig. 2. System models of (a) OOK-OCDMA with power detection and (b) DPSK-OCDMA with balanced detection.

are still not a cost-effective solution, which is the major concernfor practical applications. Besides, there have been few reportson field trials of multiuser OCDMA transmission so far [19].

In this paper, for the first time, we demonstrate the fieldtrial of a cost-effective asynchronous wavelength division mul-tiplexing (WDM)/OCDMA network using the multiport E/Din the central office, tunable transversal-filter (TVF)-type de-coder in optical network unit (ONU), and differential-phase-shift-keying (DPSK) data format. Asynchronous signals ofthree wavelengths (400-GHz spacing) and 10-OCDMA users at10.71 Gb/s/user have been successfully transmitted with a biterror rate (BER) < 10−9 without using the OT and the FEC.

II. ADVANTAGES OF DPSK-OCDMA WITH

BALANCED DETECTION

The most used modulation format for payload data inOCDMA is ON–OFF keying (OOK) with power detection,which is referred as OOK-OCDMA. Recently, the coherent

OCDMA with DPSK modulation format and balanced detec-tion (DPSK-OCDMA) has been proposed and demonstratedusing 511-chip SSFBG E/D [6]. Fig. 2(a) and (b) shows thetheoretical models of the OOK- and DPSK-OCDMA, respec-tively. In the DPSK-OCDMA system, the data are encoded bya DPSK encoder, the intensity modulator is replaced by a PM,and the photodetector is replaced by a 1-bit delay interferometeras a DPSK decoder followed by a balanced-detector. Fig. 3illustrates the eye diagrams and noise distributions (probabilitydensity function) of the different OCDMA schemes. Fig. 3(a)shows those of the received signals in OOK-OCDMA withfixed electrical threshold (Th) and optimal Th (Opt Th). Marks“1” and “0” have an asymmetric noise distribution, as shownin the figure. With the changing of the active users’ number, adynamic Th level setting is required in the receiver to achieve aminimum BER by finding the Opt Th. However, both the real-time active users number estimates and dynamical thresholdsetting are still practical issues in OCDMA receivers and willresult in additional cost. Fig. 3(b) shows the eyes and noise

WANG et al.: FIELD TRIAL OF 3-WDM × 10-OCDMA × 10.71-Gb/s ASYNCHRONOUS WDM/DPSK-OCDMA 209

Fig. 3. Comparison of eye diagrams and noise distributions of (a) OOK-OCDMA without OT, (b) OOK-OCDMA with OT, and (c) DPSK-OCDMA with fixedthreshold at 0.

Fig. 4. Performance comparisons (number of active users for a given BER versus interference level) between OOK-OCDMA and DPSK-OCDMA.(a) Comparison between DPSK-OCDMA and OOK-OCDMA with fixed and optimal threshold (with BER = 6e−5). (b) Comparison between DPSK-OCDMAand OOK-OCDMA with and without OT (with BER = 1e−9).

distribution in the OOK-OCDMA system with the OT. The per-formance could be significantly improved with the eliminationof the MAI noise by an ideal OT. However, the performanceof practical OT cannot be perfect. Supposing that the opticalsignal-to-noise ratio (OSNR) of an optical signal changes fromOSNR1 (dB) to OSNR2 (dB) after going through an OT, theOSNR improvement of the OT is OSNR2 − OSNR1 (dB). Theperformance improvement of a system using the OT is highlydependent on its OSNR improvement. This will be furthershown in the following numerical results. Fig. 3(c) shows thosein the DPSK-OCDMA. The noise has symmetric distributionsfor marks “1” and “0” in this system. Therefore, minimumBER could be easily achieved with a fixed Th at 0. Fig. 4shows the numerical results for the comparison using thesemodels [3], [6]. Fig. 4(a) shows the number of active users(K) that can be supported with BER ≤ 6 × 10−5 versus theaverage interference level ζ, which is defined as the averagecross-to-autocorrelation ratio (in decibels) [3]. The three curvesfrom right to left are for DPSK-OCDMA, OOK-OCDMA

with Opt Th, and fixed Th, respectively. For a given valueof K, the DPSK-OCDMA can tolerate about 4 dB higher ξcomparing to OOK-DPSK with Opt Th and 5–6 dB highercomparing to OOK-DPSK with fixed Th. This is a significantimprovement for OCDMA because more active users couldbe accommodated with a shorter OC length. For example, byusing a 511-chip OC (ξ ∼= −27.1 dB), about six active users(K = 6) could be supported at this BER for OOK-OCDMAwith fixed Th, K = 9 for OOK-OCDMA with Opt Th, andK = 17 for DPSK-OCDMA. Fig. 4(b) shows K versus ζ withBER ≤ 1 × 10−9. From right to left, the thick curves are forDPSK-OCDMA and OOK-OCDMA without OT (with OptTh), respectively, while the thin curves are for OOK-OCDMAusing ideal OT and an OT with 5-dB OSNR improvement,respectively. The performance improvement of using the OTin the OOK-OCDMA can be clearly seen, and it is dependenton the OSNR improvement of OT in the practical system.On the other hand, the performance of DPSK-OCDMA is closeto OOK-OCDMA with OT. Therefore, the DPSK-OCDMA

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Fig. 5. Proposed WDM/OCDMA network architecture.

is superior over the OOK-OCDMA with advantages of im-proved receiver sensitivity, better tolerance to beat noise andMAI noise without OT, and no need for dynamic Th levelsetting [6].

III. FIELD TRIAL OF MULTIUSER WDM/DPSK-OCDMA

A. Consideration of a Cost-Effective WDM/OCDMA

The WDM technique is very successful in current fiber-optic communication networks. A prospective broadband ac-cess network with a high spectral efficiency will be a hybridWDM/OCDMA network [20]. Fig. 5 shows the architectureof the proposed cost-effective WDM/OCDMA network, whichuses a large-scale multiport E/D in the central office and a low-cost E/D in the ONU. The multiport E/D [15], [21] has veryhigh PCR between auto- and cross-correlation signals, whichcan significantly suppress the MAI and the beat noise witha short OC [15]. The multiport E/D with a periodic spectralresponse can process multiple OCs in multiple wavelengthbands with a single device as shown in the inset, and the costwill be shared by all the subscribers. At the ONU side, fixedSSFBG or TVF can be used as the low-cost E/D. The hybridof SSFBG and TVF-type E/D has already been verified for useas OC E/D [22]. Here, we further used the multiport E/D as theencoder and the tunable TVF-type E/D as the decoder to verifythat this hybrid can work properly as well. Fig. 6(a) shows thewaveforms of a generated 16-chip 200 Gchip/s OCs from the16 × 16 multiport E/D (upper) and TVF-type E/D (lower).The phase pattern of the represented OC is shown on the top ofthe figure. The auto-/cross correlations of the hybrid of the mul-tiport encoder/tunable TVF decoder (hybrid E/D) are shown inFig. 6(b). The measured PCRs are shown in Fig. 6(c), together

with those of multiports E/D for four different OCs. They arein good agreement with each other, and the values range from12 to 22 dB, which is one key to enable multiuser asynchronousOCDMA by suppressing the noises.

On the other hand, the DPSK-OCDMA with a balanceddetection will be another key to enable multiuser asynchronousOCDMA at 10 Gb/s without OT and FEC, due to its superiornoise tolerance over a conventional OOK-OCDMA.

B. Experiments

Fig. 7 shows the experimental setup of the field trial formultiuser WDM/DPSK-OCDMA. The field trial was done inan optical testbed of the Japan Gigabit Network II (JGNII)[23]. JGNII is a nationwide open testbed network as shown inFig. 8(a); it is operated by the National Institute of Communica-tion and Information Technology as an ultrahigh-speed testbednetwork for R&D collaboration between industry, academia,and government. The fiber used in this experiment is installed inthe field between our laboratory in Koganei City and Otemachiof downtown Tokyo in a loop-back configuration, as shown inFig. 8(a). Fig. 8(b) shows several photos of the experimentalsetup.

Three mode-lock laser diodes generated 3-WDM pulse sig-nals with about 3.2-nm (400 GHz) channel spacing. The∼1.8-ps optical pulses were generated at a repetition rate of10.709 GHz with central wavelengths of 1550.2, 1553.4, and1556.6 nm, respectively. Each signal was modulated by alithium niobate PM (LN-PM) separately with 231 − 1 pseudo-random bit sequence from independent data sources. Thesignals were then multiplexed and sent to the port #1 of the 16 ×16 ports E/D. Inset α in Fig. 7 shows the spectrum of thismultiplexed signal. Sixteen different OCs were generated at

WANG et al.: FIELD TRIAL OF 3-WDM × 10-OCDMA × 10.71-Gb/s ASYNCHRONOUS WDM/DPSK-OCDMA 211

Fig. 6. Performance of multiport encoder with TVF decoder.

Fig. 7. Experimental setup.

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Fig. 8. (a) JGNII and the configuration of the testbed used in the experiment. (b) Measured dispersion of the whole system. (c) Photos of experimental setup.

the 16 output ports and were then mixed in an asynchronousmanner with balanced power, random delay, random bit phase,and random polarization states. Fixed fiber delay lines withincremental differences of 10 m were used in each branch todecorrelate the signals; variable optical attenuators were usedto balance the power. Tunable optical delay lines were placedas well to investigate the system performance with differentphases of SI overlapping. In a practical PON environment, thepolarization states of the signals may be random. However,for investigating the system performance in the worst sce-

nario where the interference becomes most serious, polarizationcontrollers (PCs) were placed to align the polarization statesof all the signals. Inset β in Fig. 7 shows the waveform ofthe mixed signals of 3-WDM, 12-OCDMA users. This signalwas then launched into a 100-km-installed single-mode fiber(SMF). Three spans of dispersion-compensating fiber with totaldispersions of around 430, 860, and 430 ps/nm, respectively,have been used in the transmission line to compensate thedispersion, as shown in Fig. 8(a). The dispersion of the systemis measured as shown in Fig. 8(b).

WANG et al.: FIELD TRIAL OF 3-WDM × 10-OCDMA × 10.71-Gb/s ASYNCHRONOUS WDM/DPSK-OCDMA 213

Fig. 9. Eye diagrams of (upper row) encoded, (middle row) decoded, and (lower row) electrical signals with 3 WDM and different number of active users ineach wavelength (K).

Fig. 10. BER performances.

After the transmission, the WDM × OCDMA signal was firstdemultiplexed by the WDM DEMUX with 400-GHz channelspacing and later transmitted through ∼11-km SMF beforereaching the 16-chip programmable TVF-type decoder. Thedecoder was programmed to decode four different OCs thatcorrespond to the ones generated at encoder ports 4, 8, 12,and 16. A fiber-based interferometer and a balanced detectorperform the DPSK detection. The bandwidth of the receiver

system is around 7.8 GHz, which performs the data-rate de-tection. Insets θ and ζ in Fig. 7 show the decoded signal and theelectrical signal after the balanced detector, respectively. Thedata were finally tested by the BER tester with a clock signalobtained from the clock-data-recovery circuit. Fig. 9 shows theeye diagrams of the encoded (upper row), decoded (middlerow), and the electrical (lower row) signals with 3 WDM anddifferent number of active users in each wavelength (K).

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The measured BER performances are shown in Fig. 10.Fig. 10(a) shows those for four different decoders with 3 WDM,single, and 12 active OCDMA users (K = 1, 12) in the back-to-back (B-to-B) case. Error free (BER < 10−9) has beenachieved for all the OCDMA users in 3-WDM channels. Theaverage power penalty for K = 12 to K = 1 is about 8 dB.Fig. 10(b) shows a comparison of BERs between DPSK-OCDMA and OOK-OCDMA with and without FEC for K =12 [15]. The performance has been significantly improvedin DPSK-OCDMA compared to OOK without FEC. Evencompared to OOK with FEC, the sensitivity at BER = 10−9

was improved more than 2 dB. These results verify the pre-vious statement that DPSK-OCDMA can accommodate moreactive users than OOK-OCDMA without using FEC and OT.Fig. 10(c) shows the BER performance degradation after afield transmission. For K = 12, an error floor around 10−9 hasbeen observed in several cases due to impairments during the111-km transmission and nonuniformity of the PCR [14], [15],[21]. Fig. 10(d) shows that the error-free transmission has beensuccessfully achieved for all the four decoders with 3-WDMand up to 10-OCDMA users in the field trail.

Finally, it is worth noting that all the measurements weretaken under the worst-case scenario by adjusting the tunableoptical delay lines and PCs to guarantee the asynchronousoperation [15], [18]. The threshold level was fixed to zero inthe measurement independent of K. Therefore, the dynamicthreshold level setting requirement could be relaxed in thereceiver as well. The four ports were randomly chosen forgood representativeness for all the others. The multiuser per-formances of other ports were tested to be within the spreadof the shown results. The spectral efficiency (η) is about 0.32and 0.27 b/s/Hz for B-to-B and field transmission, respectively.As a comparison, the authors in [7] and [8] have reportedWDM/OCDMA experiments with η = 1.6 and 0.125, respec-tively. However, they are synchronous approaches with strin-gent timing coordination combining with time gating [7], [8]and polarization multiplexing [7]. For asynchronous OCDMA,our result is the highest reported result so far.

IV. CONCLUSION

The field trial of a cost-effective asynchronous WDM/DPSK-OCDMA using hybrid E/D has been successfully demonstratedwith a frequency efficiency of 0.27 b/s/Hz in an asynchronousenvironment. The total capacity is 3-WDM × 10-OCDMA ×10.71 Gb/s, and the transmission distance is 111 km. Thenonuniformity of PCR is a limitation of the current device,which can be mitigated in a larger scale device with better de-sign and fabrication. Spectral efficient asynchronous OCDMAcould be expected by using a large-scale multiport E/D withhigher PCR, polarization multiplexing, and FEC.

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WANG et al.: FIELD TRIAL OF 3-WDM × 10-OCDMA × 10.71-Gb/s ASYNCHRONOUS WDM/DPSK-OCDMA 215

Xu Wang (S’91–M’98–SM’06) received theB.S. degree in physics from Zhejiang University,Hangzhou, China, in 1989, the M.S. degree inelectronics engineering from the University ofElectronics Science and Technology of China(UESTC), Chengdu, China, in 1992, and the Ph.D.degree in electronics engineering from the ChineseUniversity of Hong Kong (CUHK), Hong Kong,in 2001.

From 1992 to 1997, he was a Lecturer withthe National Key Laboratory of Fiber Optic Broad-

band Transmission and Communication Networks of UESTC. From 2001to 2002, he was a Postdoctoral Research Fellow with the Department ofElectronic Engineering of CUHK. From 2002 to 2004, he worked withthe Department of Electronic and Information Systems, Osaka Univer-sity, Osaka, Japan, as Telecommunication Advancement Organization (TAO)Research Fellow. In April 2004, he joined the Ultra-fast Photonic NetworkGroup, Information and Network Systems Department, National Institute ofCommunication and Information Technology (NICT), Tokyo, Japan, as anExpert Researcher. He is also an Adjunct Professor with two universitiesin China. His research interests include fiber-optic communication networks,optical code division multiplexing (OCDM), optical packet switching, semicon-ductor lasers, application of fiber gratings, and fiber-optic signal processing. Hehas filed three patents and is the first author of more than 70 technical papers.

Dr. Wang received the Telecommunications Advancement Research Fellow-ship by the TAO of Japan in 2002 and 2003.

Naoya Wada (M’97) received the B.E., M.E., andDr.Eng. degrees in electronics from Hokkaido Uni-versity, Sapporo, Japan, in 1991, 1993, and 1996,respectively.

In 1996, he joined the Communications Re-search Laboratory (CRL), Ministry of Posts andTelecommunications, Tokyo, Japan. He is currently aResearch Manager with the National Instituteof Communication and Information Technology(NICT), Tokyo. His current research interests are inthe area of photonic networks and optical communi-

cation technologies such as optical packet switching (OPS), optical processing,and OCDM.

Dr. Wada received the 1999 Young Engineer Award from the Instituteof Electronic and Communication Engineers of Japan and the 2005 YoungResearcher Award from Ministry of Education, Culture, Sports, Science, andTechnology. He is a member of IEEE Comsoc, IEEE LEOS, the Instituteof Electronics and Communications (IEICE), the Japan Society of AppliedPhysics (JSAP), and the Optical Society of Japan (OSJ).

Tetsuya Miyazaki (M’03) received the B.S. degreein physics from University of Tsukuba, Ibaraki,Japan, in 1985 and the M.S. and Ph.D. degreesin information processing from Tokyo Instituteof Technology, Tokyo, Japan, in 1987 and 1997,respectively.

In 1987, he joined KDDI Research and Develop-ment (R&D) Laboratories, Saitama, Japan, where heworked on coherent optical communications. From1993 to 1996, he was with ATR Optical and RadioCommunications Research Laboratories, where he

worked on fiber amplifier for optical intersatellite links. From 1996 to 2002,he was with KDDI R&D Laboratories, where he was engaged in WDMoptical networks. Since April 2002, he has been with the National Institute ofCommunication and Information Technology (NICT), Tokyo, Japan, where hehas been involved in research on ultrafast photonic networks and multilevelmodulation techniques. In 2005, he was a Group Leader with the PhotonicNetwork Group.

Dr. Miyazaki is a member of the IEEE Lasers and Electro-Optics Society(IEEE LEOS) and the Institute of Electronic, Information, and CommunicationEngineers (IEICE) of Japan.

Gabriella Cincotti (M’00–A’03–M’03–SM’06) wasborn in Naples, Italy, in 1966. She received theLaurea (M.Sc.) degree (cum laude) in electronic en-gineering from “La Sapienza” University of Rome,Rome, Italy, in April 1992.

From 1992 to 1994, she was a Project Engineerwith the microwave laboratory of ALENIA, Aeritalia& Selenia S.p.A., Rome. In October 1994, she joinedthe Department of Electronic Engineering of Univer-sity “Roma Tre,” Rome, as an Assistant Professor. InMay 2005, she became an Associate Professor with

the Department of Applied Electronics. She has authored over 70 papers andpresentations in international journals and conferences.

Ms. Cincotti is a member of the IEEE Lasers and Electro-Optics Society(LEOS), the National Inter-University Consortium for Telecommunications(CNIT), and the Inter-University Research Centre for the Physical AgentsPollution (CIRIAF).

Ken-ichi Kitayama (S’75–M’76–SM’89–F’03) re-ceived the B.E., M.E., and Dr.Eng. degrees incommunication engineering from Osaka University,Osaka, Japan, in 1974, 1976, and 1981, respectively.

In 1976, he joined the NTT Laboratory. From1982 to 1983, he was with University of California,Berkeley, as a Research Fellow. In 1995, he joinedthe Communications Research Laboratory (cur-rently, NICT), Tokyo, Japan. Since 1999, he hasbeen the Professor with the Department of Electrical,Electronic, and Information Engineering, Graduate

School of Engineering, Osaka University, Osaka. His research interests are inphotonic networks, optical signal processings, optical code-division-multiple-access systems, and radio-on-fiber communications. He has published over210 papers in refereed journals, written two book chapters, and translated onebook. He holds more than 30 patents.

Dr. Kitayama currently serves on the Editorial Boards of the IEEEPHOTONICS TECHNOLOGY LETTERS, IEEE TRANSACTIONS ON

COMMUNICATIONS, Optical Switching, and Networking as an AssociateEditor. He received the 1980 Young Engineer Award from the Institute ofElectronic and Communication Engineers of Japan, the 1985 Paper Award onOptics from the Japan Society of Applied Physics, and the 2004 AchievementAward of the IEICE of Japan. He is a Fellow of the IEICE of Japan.