Recognition of Wavelength-multiplexed Labels with Acoustooptic Waveguide Circuit for Hierarchical Photonic Routing

Transcription

1 PIERS ONLINE, VOL. 5, NO. 4, Recogniion of Wavelengh-uliplexed Labels wih Acousoopic Waveguide Circui for Hierarchical Phoonic Rouing Nobuo Goo and Yasuisu Miyazai 2 The Universiy of Toushia, Japan 2 Aichi Universiy of Technology, Japan Absrac High-speed opical processing for pace rouing can overcoe bolenec in largecapaciy phoonic newors. We have sudied on collinear acouso-opic (AO) swiches and applicaions o opical label recogniion. Since parallel cobinaion of collinear AO swiches can handle wavelengh-division-uliplexed (WDM) opical pulses, recogniion for opical labels encoded in specral and ie doains can be realized. In his repor, we discuss recogniion of layer-srucure labels for hierarchical rouing conrol. By eploying WDM ie-series labels including idenifying bis, he labels corresponding o each layer can be recognized. The recogniion characerisics are confired by copuer siulaion.. INTRODUCTION Broadband phoonic newor has been exensively sudied o realize high-speed and low-power consupion rouing syse. In opical label rouing newor, label processing a rouers can be faser by using opical signal processing. Various ypes of opical label recogniion and swapping syses have been repored [, 2]. Hierarchical neworing has also been sudied for effecive rouing [3, 4]. We have invesigaed acouso-opic (AO) devices [5] and heir applicaions o label processing circui [6, 7]. In paricular, we have repored circuis for opical labels encoded in ie and specral doains o use effecively he unique naure of collinear AO devices, ha is, opical uliple wavelenghs can be independenly processed by frequency uliplexed surface acousic waves (SAWs). In his repor, we consider a label recogniion circui wih a new label srucure for hierarchical rouing. The principle of he proposed waveguide circui is discussed wih copuer siulaions. 2. HIERARCHICAL NETWORK AND ROUTING Figure (a) shows a wo-layer newor as an exaple of hierarchical newors. By eploying layersrucure labels, rouing processing can be sipler and faser. We consider a code for M-layer rouing newor as represened by C code = (C L, C L2,..., C LM), () where, CLi represens a code in he ih layer. A label rouer for M = 2 is shown in Fig. (b). The exraced label is processed o find wheher he s-layer label CL is ached wih he label CL of he local newor. If hese labels are ached, he 2nd-layer label is exained o find is desinaion oupu por. If he s labels are no ached, his pace is forwarded o a border rouer by cuing hrough his rouer. 3. LABEL STRUCTURE AND RECOGNITION CIRCUIT A proposed label srucure is shown in Fig. 2(a). The rouing code in each layer consiss of N pulses wih he inerval of p. Each pulse has N WDM coponens which are differen aong layers. The ih-layer code consiss of i,j, (j =,..., N ). In advance of he rouing code, M idenifying (ID) pulses having inerval of N p are placed. The whole label can be wrien as where, he ID pulse rain is wrien as C label = (C id, C L, C L2,..., C LM), (2) C id = (c id,,,...,, c id,2,,...,, c id,m,,..., ) (3)

2 wih each ID pulse PIERS ONLINE, VOL. 5, NO. 4, c id,n = (,,..., ) n =,..., M. (4) The WDM pulse rain for rouing codes is wrien for M = 3 as c,, c,2, c,3, c,,2 c,2,2 c,3,2 c,,3 c,2,3 c,3,3 c 2,, Ccode = (c, c 2,..., c c 2,2, c 2,3, 3N ) = c 2,,2 c 2,2,2 c 2,3,2. (5) c 2,,3 c 2,2,3 c 2,3,3 c 3,, c 3,2, c 3,3, c 3,,2 c 3,2,2 c 3,3,2 c 3,,3 c 3,2,3 c 3,3,3 Layer Layer Layer 2 Layer 2 Layer 2 Layer Label Exracion Opical Elecrical Recogniion of CL Recogniion of CL 2 F-F CL = CL Opical Swich Delay L = F-F: Flip-Flop F-F F-F F-F Opical Swich Por Por 2 Por N Local newor (defaul) Por C CL (cu hrough o border rouer) (a) (b) Figure : (a) Hierarchical rouing newor and (b) opical rouer. An inegraed-opic processor consising of parallel AO swiches and delay lines is shown in Fig. 2(b). The inciden label is divided ino N + pulse rains. The parial labels or he whole label o be ached in his device are represened by frequency-uliplexed SAWs. The label pulse rains are wavelengh-selecively swiched and he oupus are balanced deeced wih phoodiodes (PDs). The elecric oupu signals are elecrically uliplied. The M ached oupu pulses correspond o label aching of each layer codes. Since he SAWs represening a code o be recognized do no need o be changed during recogniion, he slow swiching speed of AO devices does no resric he processing speed for label recogniion. c M, N Mh N bi c M, 2nd N bi s N bi c2, N c, N Mh IDbis 2nd p N p N p N p MN p...,,n,... 2, 2,N... M, M, N (a) c, c idm c id2 c id s p C label WDM (,, N ) M Divider C l' (N -) p (N -2) p (N -l ) p Delay lines (b) SAW (code ) Sz (,) Sz (,) 2 Sz (,) l' Sz (,) N [(M+)N -] p PD Elecrical uliplier Mached oupu Figure 2: (a) Srucure of he hierarchical rouing label and (b) label recogniion AO processor.

3 PIERS ONLINE, VOL. 5, NO. 4, PRINCIPLE OF CODE RECOGNITION We consider he elecric field of he inciden opical pulse rain represening code as given by M M N N E () = E c id,n g in, ( ) exp[jω ( )]+E c n,l,i g in,( ) exp[jω n,i ( )], (6) n= n= l= i= where, g in, () denoes he pulse envelope of a single pulse, ω i is he angular frequency of wavelengh i, and and are defined by = ( )N p, = [(M + n )N + l ] p. (7) An inciden pulse rain ino he l h AO swich afer passing he divider and a delay waveguide is wrien as El () = N + E ( (N l ) p ). (8) When a code o be recognized is code, he SAW srain in he l h AO swich is wrien as M Sl (, z) = N c n,l,i s cos(ω n,i K n,i z), (9) n= i= where, s is srain coponens relaed o AO swiching, Ω n,i and K n,i are he angular frequency and he propagaion consan of he SAWs. The swiched opical signal has he oupu { E, E M ou,l () = c id,n c,l N +, g ou,( 3 ) exp[j(ω n, Ω n, )( 3 )] n= N + c n,l,i c n,l,i g ou,( 2 ) exp[j(ω n,i Ω n,i )( 2 )], () where, 2 and 3 are defined by n= l= i= 2 = T + (N l ) p + l SW N(n, i)/c, 3 = (nn l ) p, () where, c is he opical velociy, N(n, i) is he effecive index for he guided wave a wavelengh n,i = 2πc/ω n,i, g ou, () is he envelope of he swiched pulse, and l SW is he AO ineracion lengh. A coon phase er ha changes hrough propagaion along he waveguides is oied for sipliciy. The opical field exiing fro he unswiched por is given by E, ou2,l () = { M E N + n= c id,n c,l, g ou,( 3 ) exp[j(ω n, Ω n, )( 3 )] +c id,n c,l, gres ou,( 3 )exp[jω n, ( 3 )] N [ + c n,l,i c n,l,i g ou,( 2 )+c n,l,i c n,l,i gres n= l= i= ou,( ) ] exp[j(ω n,i Ω n,i )( 2 )],(2) where, g res ou, () denoes he residual coponen due o icopleeness of swiching, and c n,l,i = c n,l,i. When we assue he AO swiching o be ideal as given by I, l () N + N + g ou, g in,, he elecric differenial curren fro he PDs is wrien as {[ I ( ) 2 ( c id,nc,l, c id,n c,l, n= l= i= g res ou,, (3) ) 2 ] g 2 in,( 3 ) [ ( ) 2 ( ) ] 2 c n,l,i c n,l,i c n,l,i c n,l,i gin,( 2 2 ). (4)

4 PIERS ONLINE, VOL. 5, NO. 4, By uliplying oupu currens fro N AO swiches wih he elecrical uliplier, we obain N ( ) N I, ()= I, I N N [ l ()= (c n,l,i N + c n,l,i )2 (c n,l,i c n,l,i )2] gin,( 2 2 ). (5) l = l = n= l= i= To evaluae correlaion in each-layer code, ID bi pulses are used. The pulse rain passed hrough only he delay waveguide, which is he lowes waveguide in he AO processor, is convered o elecric curren wih he PD as I ou,id() = I E 2 E ou,id 2 = { M N + n= c 2 id,n g2 in,( 4 ) + N n= l= i= (c n,l,i )2 g 2 in,( [(M + 2)N ] p l SW N /c). (6) Here, we assue 2 = 4 and N(n, i) = N resuling in l = l, and 2 is rewrien as 2 = (M + n)n + l SW N /c. (7) By uliplying he curren fro he AO swiches and he curren for idenifying pulse rain, we obain I, ou () = In, () Iou,ID() ( ) { N+ M N N = N + n= l= i= c 2 id,n ( (M + n)n + l SW N /c) 5. COMPUTER SIMULATION OF CODE RECOGNITION [ (c n,l,i c n,l,i )2 (c n,l,i c n,l,i )2] g 4 in,. (8) In he previous analysis, he ideal swiching characerisics given by Eq. (3) were assued. In his secion, we evaluae he code recogniion aing he swiching response of AO swiches ino consideraion. When he bi rae of he opical pulses becoes higher, broader frequency specru is accopanied in he opical signal. The filering characerisics of he AO swiches affec he swiching response for high bi-rae pulses. We assue ha he inciden pulse rain consiss of 9 pulses (M = 3, N = 3) wih bandwidh of 6 GHz, pulse period of 2 ps and pulse widh of 5.9 ps. Labels in each layer consis of WDM pulses of N = 3. We also assue he ineracion lengh of he AO swiches o be l SW = 6. We consider OOK orhogonal codes as each WDM pulse. For N = 3, we eploy ] ] ] c i = {a, a 2, a 3 = {[, [, [. (9) a a a a a 2 a 3 a a 2 a Wavelengh Tie (ps) Figure 3: Wavelengh coponens of elecric fields of opical inciden pulse rain for C = (a, a, a, a, a 2, a 3, a, a 2, a 3 ).

5 PIERS ONLINE, VOL. 5, NO. 4, As an exaple of opical inciden code, we consider C = (a, a, a, a, a 2, a 3, a, a 2, a 3 ). Fig. 3 shows he wavelengh coponens of he label consising of he code and ID pulses a wavelengh,. When he AO processor is se o recognize code of C = (a, a, a, a 2, a 2, a 2, a, a 2, a 3 ) wih SAWs, he oupu appears a he firs and he hird ID pulses as shown in Fig. 4(a). The second layer code is unached in his case. If all he hree layer codes are ached, hree pulses are obaind. Nex, we consider code aching for a single layer code. To recongnize he second layer code, he AO processor is assued o be se for C = ( a, a 2, a 3 ). The oupu curren has a posiive pulse a he second ID pulse and negaive pulses a oher ID pulses as shown in Fig. 4(b). When he second layer code is unached by seing he AO processor wih C = ( a 2, a 2, a 2 ), he oupu curren is obained as shown in Fig. 4(c). Oupu Curren (Arb. Uni).5.5 a a a a a 2 a 3 a a 2 a 3 a a a a 2 a 2 a 2 a a 2 a Tie (ps) Oupu Curren (Arb. Uni) a a a a a 2 a 3 a a 2 a a a 2 a Tie (ps) Oupu Curren (Arb. Uni) a a a a a 2 a 3 a a 2 a a 2 a 2 a Tie (ps) (a) (b) (c) Figure 4: Oupu curren fro uliplier for SAWs represening (a) C = (a, a, a, a 2, a 2, a 2, a, a 2, a 3 ), (b) C = ( a, a 2, a 3 ), and (c) C = ( a 2, a 2, a 2 ). 6. CONCLUSION We discussed opical label aching using an inegraed-opic device and an elecrical uliplier. By inroducing WDM address bis and ID bis, parial label aching is perfored. We will furher invesigae he layer-srucure rouing. REFERENCES. Bluenhal, D. J., B. E. Olsson, G. Rossi, T. E. Diic, L. Rau, M. Masanovic, O. Lavrova, R. Doshi, O. Jerphagnon, J. E. Bowers, V. Kaan, L. A. Coldren, and J. Baron, All-opical label swapping newors and echnologies, J. Lighwave Technol., Vol. 8, No. 2, , Kiayaa, K., N. Wada, and H. Soobayashi, Archiecural consideraions for phoonic IP rouer based upon opical code correlaion, J. Lighwave Technol., Vol. 8, No. 2, , Seddighian, P., S. Ayoe, J. B. Rosas-Fernandez, J. Penon, L. A. Rusch, and S. LaRochelle, Label sacing in phoonic pace-swiched newors wih specral apliude code labels, J. Lighwave Technol., Vol. 25, No. 2, , Feb Yaanaa, N., K. Shiooo, and E. Oi, GMPLS Technologies Broadband Bacbone Newors and Syses, CRC Press, Boca Raon, Kondo, T., Y. Miyazai, and Y. Aao, Opical unable swiched direcional couplers consising of wo hin-fil waveguides using surface acousic waves, Jpn. J. Appl. Phys., Vol. 7, No. 7, , Goo, N. and Y. Miyazai, Recogniion of wavelengh-division-uliplexed ie-series opical coded labels using collinear acousoopic devices wihou ie gaing for phoonic rouing, Jpn. J. Appl. Phys., Vol. 46, No. 7B, , Goo, N. and Y. Miyazai, Recogniion characerisics of layered code for opical ie-series wavelengh-division-uliplexed labels using collinear acousoopic swich arrays, Jpn. J. Appl. Phys., Vol. 47, No. 5, , May 28.