7th WEA International Conference on Electric Power ytem, High Voltage, Electric Machine, Venice, Italy, ovember -3, 007 36 Lo Reduction of A/AC etwork with Holograhic Otical witche Jiun-hiou Deng, Chien-Yi Lee, Ming-Feng Lu, and Yang-Tung Huang Det. of Electronic Engineering, MingHing Univerity of cience and Technology, Hin-hing Rd., Hin-Feng, Hin-Chu, Taiwan, 304, R. O. C. Det. of Electronic Engineering and Intitute of Electronic, ational Chiao Tung Univerity Abtract: - Uing holograhic otical witche to imlement litter/ combiner network not only ignificantly ave the ace of the whole ytem and efficiently eliminate all interconnection line and croover, but alo reduce the number of witche from - to log. The ytem inertion lo can alo be ignificantly minimized by combining the unique feature of the litter/ combiner network and holograhic otical witche. Key-word: holograhic otical witch, otical witch, olarization beam litter, otical interconnection network, ytem inertion lo, olarization elective element. Introduction litter/ combiner (A/AC) network [, ] have ome advantage uch a trictly nonblocking, imle routing-algorithm, low ytem-inertion-lo, zero differential lo, fewer driver, and the bet ignal-to-noie ratio characteritic. However, it require a large number of witche, interconnection line, and croover to contruct an A/AC network. In recent reearche, thee drawback can be olved by uing olarization elective element, like holograhic and rim olarization elective element (PB) [3-6]. An A/AC network a hown in Fig. conit of litter and combiner. The number of litter and combiner are both. The baic otical witching element of litter and combiner are and otical witche, reectively, a hown in Fig.. Both of litter and combiner are formed by - witche arranged in a log -tage binary tree tructure [, ], and only one otical beam can a through each litter or combiner. Holograhic Otical witche Fig. 3 and 3 how the two tate of a holograhic otical witch (HO). A HO conit of a holograhic PB and two electro-otic halfwave late () [7]. The are ued to kee the olarization of outut beam the ame a that of inut, and can be controlled by ingle driver. Fig.. The tructure of an A/AC network. Inut litter litter litter Outut Inut Fig.. The baic otical witche in A/AC network: otical witch. otical witch. The initial inut and final outut otical beam are -olarized a hown in thee figure. When are in, the olarization of the otical beam i not altered, o it direction will not be altered by the holograhic grating. In thi cae, the HO rovide traight function a hown in Fig. 3. imilarly, the otical ignal Outut
7th WEA International Conference on Electric Power ytem, High Voltage, Electric Machine, Venice, Italy, ovember -3, 007 37 from the outut channel will follow the ame ath backward with correonding olarization and finally reach the inut channel. in Inut HG I HG O in Outut Inut Fig. 3. The HO with holograhic PB; traight tate and turn tate, where i the electro-otic halfwave late and the HG i the holograhic grating. When are, the olarization of the otical beam i rotated by 90 and i -olarized. Thi otical beam i diffracted by the inut couling holograhic grating (HG I ) and normally couled out with a conjugate diffraction by the outut couling holograhic grating (HG O ). In thi cae, the HO rovide turn function a hown in Fig. 3. Alo, the otical ignal from the outut channel can follow the ame ath backward with correonding olarization and finally reach the inut channel. Obviouly, thi HO rovide bi-directional witching function. Therefore, a HO can act a a HO. By the unique feature of the A/AC network, the tructure of HO can be imlified a hown in Fig. 4. A imlified HO conit of a holograhic PB and an electro-otic halfwave late () [4, 5]. All of the witching ituation are hown in Fig. 4. In Fig. 4 and, the inut otical beam are -olarized and in Fig. 4(c) and (d), the inut otical beam are -olarized. In Fig. 4, an -olarized inut otical beam ae directly through the in and the dielectric ubtrate. In Fig. 4(c), the inut otical beam i -olarized and the i. After aing through the, the olarization of the otical beam i rotated by 90 and i -olarized. In thi ituation, thi otical beam can directly a through the dielectric ubtrate. Therefore, both of Fig. 4 and (c) rovide the traight tate and the outut otical beam are -olarized. HG I θ D HG O Outut in Inut in Inut (c) Outut Outut Inut Fig. 4. A imlified HO conit of a holograhic PB and an electro-otic halfwave late; traight tate, turn tate, (c) turn tate, and (d) traight tate, where i the electro-otic halfwave late. In Fig. 4, the i. While the inut otical beam aing through the, the olarization of the otical beam i rotated by 90 and i -olarized. Thi inut otical beam i diffracted by the inut couling holograhic grating (HG I ) and normally couled out with a conjugate diffraction by the outut couling holograhic grating (HG O ). In Fig. 4(d), the inut otical beam i -olarized and the i in. In the dielectric ubtrate, thi inut otical beam will follow the ame ath a Fig. 4 to outut. Hence, both of Fig. 4 and (d) rovide the turn tate and the outut otical beam are -olarized. Obviouly, thi HO rovide bi-directional witching function. Therefore, a HO can act a a HO. The otical beam from the outut channel can follow the ame ath backward with correonding olarization and finally reach the inut channel. 3 A/AC etwork with Holograhic Otical witche A 4 4 A/AC network with ordered tage number i hown in Fig. 5, which conit of 4 litter and 4 combiner. The number of 4 litter and 4 combiner are both four. A 4 litter with HO conit of three HO a hown in Fig. Inut (d) Outut Outut
7th WEA International Conference on Electric Power ytem, High Voltage, Electric Machine, Venice, Italy, ovember -3, 007 38 6. Becaue only one otical beam ae through thi 4 litter, two HO at tage can be driven by one driver; therefore, only need one. Thee two holograhic PB can be combined together into one holograhic PB. After otimal deign, both of interconnection line can be eliminated a hown in Fig. 6 [4]. connect to O 4 and the outut otical beam i -olarized. Both of thee two tage of HO are in turn tate. Inut tage tage O () O () tage tage tage tage 3 4 O 3 () O 4 () Inut tage tage O () 3 3 O () O 3 () 4 4 O 4 () Fig. 5. 4 4 A/AC network with ordered tage number. Table The witching tate of HO of the 4 litter. HO witching tate Outut Cannel Polarization of the Outut Otical Beam tage tage O traight traight -olarized O traight Turn -olarized O 3 Turn traight -olarized O 4 Turn Turn -olarized According to the witching tate of thee two HO, the connection ath in the 4 litter can be determined a hown in Table. While thee two tage of HO are in traight tate, the inut connect to O and it i -olarized at outut channel. If tage i in traight tate and tage i in turn tate, the inut i connected to O and the outut otical beam i -olarized. In the ooite cae, tage i in turn tate and tage i in traight tate, the inut i connected to O 3 and the outut otical beam i -olarized. At the lat cae, the inut Fig. 6. 4 litter with three imlified HO; a comact tructure of 4 litter with two imlified HO. A 4 4 A/AC network with HO i hown in Fig. 7. In thi figure, there are ome olarization tate between the litter and the combiner are unmatched, uch a from I to O. In thi ituation, the econd outut of the firt litter i connected to the firt inut of the econd combiner. When the inut and outut otical beam are -olarized, the olarization of the econd outut of the firt litter and the firt inut of the econd combiner are - and -olarized, reectively. In thi cae, thi connection ath can not be built. By cacading a halfwave late (HWP) between thee two oint a hown in Fig. 7, the roblem can be olved. However, thee halfwave late increae the inertion lo and ytem cot. Thee roblem can be olved by uide down the arrangement of the even number litter and combiner a hown in Fig. 8. In thi figure, all of the connection ath have the matched olarization. Comared with the original deign
7th WEA International Conference on Electric Power ytem, High Voltage, Electric Machine, Venice, Italy, ovember -3, 007 39 [4], half of the number of will be reduced. Becaue each tage of HO ha been reduced one, the ytem inertion lo will be decreaed from log (L +L PB ) to log (L +L PB ), where L and L PB are the inertion loe of the electro-otic halfwave late and holograhic PB, reectively. Hence, the inertion lo and ytem cot can be efficiently reduced. I I I 3 I 4 HWP Fig. 7. A 4 4 A/AC network with HO in which need ome halfwave late (HWP) to olve the olarization unmatched roblem. 4 Concluion In thi tudy, uing holograhic otical witche to build the litter/ combiner network ha been rooed. With the unique feature of comactne and flexibility, holograhic otical witche eliminate all interconnection line between witche. ot only the volume of all ytem but alo the number of required comonent are reduced ignificantly. Eecially, the number of witche of an litter/ combiner network decreaed from - to log. In thi reentation, according to the network characteritic, the tructure of the holograhic otical witch ha been modified. Becaue each tage of HO ha been reduced one, the ytem inertion lo will be decreaed from log (L +L PB ) to log (L +L PB ). Thi modification reult that the inertion lo and ytem cot can be efficiently reduced. O O O 3 O 4 I I I 3 I 4 Fig. 8. A 4 4 A/AC network with HO in which the arrangement of the even number litter and combiner have been uide downed to olve the olarization unmatched roblem. Acknowledgement Thi reearch wa uorted by MingHing Univerity of cience and Technology under contract MUT 96-E-003. Reference: [] R. A. anke, Architecture for Guided- Wave Otical ace witching ytem, IEEE Communication Magazine, vol. 5, 987,. 4-48. [] C. C. Lu and R. A. Thomon, The Double- Layer etwork Architecture for Photonic witching, IEEE Tranaction on Lightwave Technology, vol., 994,. 48-489. [3] J.-. Deng and Y.-T. Huang, Multitage Tye etwork with Holograhic Otical witche, Proceeding of PIE, vol. 400, 995,. 35-43. [4] J.-. Deng, C.-P. Lee, M.-F. Lu, and Y.-T. Huang, A/AC etwork with Holograhic Otical witche, International Journal Of Microwave And Otical Technology, vol., 006,. 570-575. [5] G. A. De Biae, Otical Multitage Interconnection etwork for Large-cale Multiroceor ytem, Alied Otic, vol. 7, 988,. 07-0. O O O 3 O 4
7th WEA International Conference on Electric Power ytem, High Voltage, Electric Machine, Venice, Italy, ovember -3, 007 330 [6] M. Cao, Q. Hua, Z. Wana, F. Luo, A novel routing otical matrix witching method, Otic Communication, 00,. 63-70. [7] Dilaytech Aia-Pacific, htt://www.dilaytech.com/roduct/hotonic /index.html.