AS/AC Network with Holographic Optical Switches

Transcription

1 570 ITERATIOAL JOURAL OF MICROWAVE AD OPTICAL TECHOLOGY VOL., O., AUGUST 006 AS/AC ework wih Holographic Opical Swiches Jiun-Shiou Deng *, Chi-Ping Lee, Ming-Feng Lu,, an Yang-Tung Huang Dep. of Elecronic Engineering, MingHing Universiy of Science an Technology, Hsin-Shing R., Hsin-Feng, Hsin-Chu, Taiwan, 0, R. O. C. Dep. of Elecronics Engineering an Insiue of Elecronics, aional Chiao Tung Universiy * Tel: ex. 60, Fax: , js@mus.eu.w Absrac -- The holographic opical swiches are hree-imensional evices, having he characerisics of flexibiliy an compacness. The proceure o realize a acive splier an acive combiner nework wih holographic opical swiches is iscusse in eail. Afer opimum esign, he unique feaures of compacness an flexibiliy of holographic opical swiches no only significanly saves space of sysem an efficienly eliminaes all inerconnecion lines an crossovers, bu also reuces he number of swiches. Inex Iems -- holographic opical swich, opical swich, polarizaion beam splier (PBS), opical inerconnecion nework. srucure []-[], an only one opical beam passes hrough each acive splier or acive combiner. Acive Splier Acive Splier Acive Combiner Acive Combiner I. ITRODUCTIO There are some avanages for acive splier an acive combiner (AS/AC) neworks, like sricly nonblocking, simpler rouing-algorihm, lower sysem-inserion-loss, zero ifferenial loss, fewer rivers, an he bes signal-o-noise raio characerisics. However, hey require a large number of swiches, inerconnecion lines, an crossovers. Acive Splier Fig. The srucure of an AS/AC nework. Acive Combiner An acive splier an acive combiner nework as shown in Fig. consiss of acive spliers an acive combiners. The numbers of acive spliers an acive combiners are boh. The basic opical swiching elemens of acive splier an acive combiner are an opical swiches, respecively, as shown in Fig.. Boh of acive splier an acive combiner are forme wih - swiches arrange in a log -sage binary ree Fig. The basic opical swiches in AS/AC neworks: opical swich. opical swich. The acive splier an a acive combiner, which are subneworks o buil a AS/AC nework, wih orere numbers of sages, channels, an swiches are shown in Fig. an, respecively. Boh of hem have wo sages. IJMOT ISRAMT 006

2 57 ITERATIOAL JOURAL OF MICROWAVE AD OPTICAL TECHOLOGY VOL., O., AUGUST 006 In Fig., S i-j represens he j h swich in sage i, I 0 represens inpu channel, an O n represens oupu channel n. If inpu I 0 is connece o O, he connecion pah consiss of wo swiches: S - an S -. The swiching sae of S - is in he sraigh sae an S - is in he urn sae. In his subnework, Sage has wo opical swiches: S - an S -. Because only one opical beam passes hrough his acive splier, no opical beam passes hrough S -. The swiching sae of S - can be se he same as S - ; herefore, hese wo opical swiches can be conrolle by one river. In oher wors, each acive splier only nees log rivers. Because acive combiner has he same siuaion as acive splier, each acive combiner requires log rivers, oo. Therefore, he oal number of rivers of an AS/AC nework is log []-[]. I 0 Sage Sage O 0 O I I Sage Sage O 0 eliminae he necessiy of inerconnecion lines beween swiches [5]-[0]. The large number of inerconnecion lines of AS/AC nework can be eliminae by using hese HOSs. II. HOLOGRAPHIC OPTICAL SWITCHES Fig. an show wo saes of a HOS. A HOS consiss of a holographic PBS an wo elecro-opic halfwave plaes[7]. The halfwave plaes are use o keep he polarizaion of oupu beam he same as ha of inpu, an can be conrolle by single river. The iniial inpu an final oupu opical beams are s-polarize as shown in hese figures. When elecro-opic halfwave plaes are inacive, he polarizaion of he opical beam is no alere, so is irecion will no be alere by he holographic graings. In his case, he HOS provies sraigh connecion as shown in Fig.. Similarly, he opical signal from oupu channel will follow he same pah backwar wih corresponing polarizaion an finally reach inpu channel. S - S - S - S - O O I I : inacive : acive S - S - Fig. Subneworks of a AS/AC nework: acive splier; acive combiner. HG I ielecric subsrae HG O θ D sub To buil an AS/AC nework wih woimensional inegrae elecro-opic swiches, he number of inerconnecion lines beween swiches is very large, an hen requires a large number of crossovers, which in urn increases he ifficuly of manufacuring an inuces aiional loss []. To buil an AS/AC nework wih prism PBSs, aiional mirrors are require o guie oupu beams o he succeeing swiches. The holographic opical swiches (HOSs) are hree-imensional evices, having he characerisics of flexibiliy an compacness []-[]. Many neworks consruce by hese swiches have been propose. HOSs can : inacive : acive Fig. The HOS wih holographic PBS; sraigh sae an urn sae, where is he elecro-opic halfwave plae an he HG is he holographic graing. When elecro-opic halfwave plaes are acive, he polarizaion of he opical beam is roae by 90 an is p-polarize. This opical beam is iffrace by he inpu coupling holographic graing (HG I ) an normally couple ou wih a conjugae iffracion by he oupu coupling c IJMOT ISRAMT 006

3 57 ITERATIOAL JOURAL OF MICROWAVE AD OPTICAL TECHOLOGY VOL., O., AUGUST 006 holographic graing (HG O ). In his case, he HOS provies urn connecion as shown in Fig.. Also, he opical signal from oupu channel can follow he same pah backwar wih corresponing polarizaion an finally reach inpu channel. Obviously, his HOS provies bi-irecional swiching funcion. Therefore, a HOS can ac as a HOS. In his HOS, he isance beween wo oupu channels is c an he corresponing hickness of he ielecric subsrae is sub. The relaion beween hese wo parameers is sub = c co θ. () D where θ D is he iffracion angle. In oher wors, when he isance beween hese wo oupu channels in he HOS is change o c, he corresponing hickness of he ielecric subsrae nees o expan o sub. III. AS/AC ETWORK WITH HOLOGRAPHIC OPTICAL SWITCHES This secion escribes how o buil a AS/AC nework wihou inerconnecion line an crossover by using HOSs. Afer opimal esign, he final configuraion no only saves he space require for he whole sysem an eliminaes all inerconnecion lines an crossovers, bu also reuces he number of swiches. A AS/AC nework wih orere sages number is shown in Fig. 5, which consiss of acive spliers an acive combiners. The numbers of boh acive spliers an acive combiners are four. Fig. 6 shows a acive splier wih HOSs, which consiss of hree HOSs. Because only one opical beam passes hrough his acive splier, wo HOSs a Sage can be riven by one river; herefore, only nee one pair of s. These wo holographic PBSs can be combine ogeher ino one holographic PBS as shown in Fig. 6. Therefore, wo HOSs a Sage are replace by a single HOS. This acive splier only nees wo HOSs an he number of swiches is reuce. Wih he same meho, boh of he acive splier an acive combiner only nee log HOSs. Obviously, he number of swiches is ecrease by using HOSs o buil hese acive spliers an acive combiners. Therefore, an AS/AC nework consiss of acive spliers an acive combiners, an he numbers of hese spliers an combiners are boh. The number of swiches of an AS/AC nework has significanly been reuce from - o log. Sage Sage Sage Sage Fig. 5 AS/AC nework wih orere sages number. As shown in Fig. 6, wo inerconnecion lines connec he oupu channels of Sage an he inpu channels of Sage. The isance beween he oupu channels a Sage is, an he isance beween he inpu channels a Sage is. For eliminaing hese wo inerconnecion lines, hey have o be arrange parallel an compleely normal o HOSs. Therefore, he isance beween he oupu channels a Sage has o be ajuse o. Accoring o Eq. (), he corresponing hickness of he ielecric subsrae mus change o as shown in Fig. 6(c). Because boh of inerconnecion lines are parallel an compleely normal o HOSs, wo HOSs can be irecly packee ogeher as shown in Fig. 6(), an no inerconnecion lines are require. Because HOSs are bi-irecional evices, his acive splier can also funcion as a acive combiner. IJMOT ISRAMT 006

4 57 ITERATIOAL JOURAL OF MICROWAVE AD OPTICAL TECHOLOGY VOL., O., AUGUST 006 Sage Sage Sage Sage Sage Sage A AS/AC nework wih HOSs is shown in Fig. 7. In his figure, acive spliers or acive combiners on each sage all have he same srucure incluing he corresponing hicknesses of ielecric subsraes. All of he HOSs a he same sage can be forme on he same holographic PBS as shown in Fig. 8. In his figure, four s are forme on a holographic PBS a each sie. The firs pair of s are (0, ), which consruc he firs HOS. The secon, hir, an las pairs of s are (0, ), (0, ), an (0, ), respecively. Four HOSs are consruce by four pairs of s an one holographic PBS. Wih he same meho, HOSs can be consruce wih pairs of s an one holographic PBS. Because here are log sages in an AS/AC nework [, ], his nework nees log holographic PBSs wih ifferen corresponing hicknesses of ielecric subsraes o consruc log HOSs. Sage Sage Sage Sage (c) Sage Sage () Fig. 6 acive splier wih hree HOSs; acive splier wih wo HOSs; (c) he same as excep ha he inerconnecion lines are parallel an compleely normal o HOSs; an () a compac srucure of acive splier wih wo HOSs. Fig. 7 A AS/AC nework wih HOSs. Afer suiably ajusing he posiions an orienaions of all HOSs as shown in Fig. 9, all inerconnecion lines beween HOSs can be arrange o become parallel an compleely normal o HOSs. Therefore, all HOSs can be irecly packee ogeher as shown in Fig. 0, an no inerconnecion line is require. Finally, a compac nework is buil by using HOSs wihou any inerconnecion line an crossover. IJMOT ISRAMT 006

5 57 ITERATIOAL JOURAL OF MICROWAVE AD OPTICAL TECHOLOGY VOL., O., AUGUST holographic graing number of require componens are reuce significanly. Especially, he number of swiches of an acive splier an acive combiner nework ecrease from - o log. Sage Sage Sage Sage ielecric subsrae Fig. 8 Four HOSs consruce by four pairs of s form on a holographic PBS. Sage Sage Fig. 9 The AS/AC nework afer rearranging all HOS s posiion an orienaion. (All inerconnecion lines are parallel, an compleely normal o he swiches.) IV. COCLUSIO Sage Sage In summary, we emonsrae he acive splier an acive combiner nework which buil by holographic opical swiches. Wih he unique feaures of compacness an flexibiliy, holographic opical swiches efficienly eliminae all inerconnecion lines beween swiches. o only he volume of all sysem bu also he Fig. 0. Three-imensional compac configuraion of an AS/AC nework. ACKOWLEDGEMET This research was suppore by he aional Science Council of he R. O. C. uner conrac SC 89-5-E REFERECES [] R. A. Spanke, Archiecures for Guie- Wave Opical Space Swiching Sysems, IEEE Communicaions Magazine, vol. 5, pp. -8, 987. [] C. C. Lu an R. A. Thompson, The Double- Layer ework Archiecure for Phoonic Swiching, IEEE Transacions on Lighwave Technology, vol., pp. 8-89, 99. [] C.-T. Lea, Crossover Minimizaion in Direcional-Couple-Base Phoonic Swiching Sysems, IEEE Trans. on Communicaions, vol. 6, pp. 55-6, 988. [] Y.-T. Huang an Y.-H. Chen, Polarizaion- Selecive Elemen wih a Subsrae-Moe Graing Pair Srucure, Opics Leers, vol. 8, pp. 9-9, 99. [5] Y.-T. Huang an Y.-H. Chen, Opical swiches wih a subsrae-moe graing srucure, Opik, vol. 98, pp. -, 99. [6] Y.-T. Huang, Polarizaion-selecive volume holograms: general esign, Applie Opics, vol., pp. 5-0, 99. [7] J.-T. Chang, D.-C. Su, an Y.-T. Huang, Subsrae-moe holographic polarizaion- IJMOT ISRAMT 006

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