Design And Research Of Technology For Bulk Silicon Micromechanical Optical Switch

With the development of optical fiber communication technology and application ofDense Wavelength Division Multiplexing(DWDM), all optical exchange has become a trend,and optical switch is a key device which can implement route selection, wavelengthselection, optical cross connects, self-cure protect. With the development of MEMStechnology, MOEMS optical switch arrays that integrate MEMS and optical device willbecome main device in all optical networks. Many academies at abroad are concentrated onthe research of MOEMS switch arrays, and have made a great deal of progress. Our countryhas also made much progress, though it has not been long since we researched MOEMSoptical switches. Most of the organizations that are doing research works are very famousuniversities and academies having advantaged technology such as 13th Institute of CETC,Jilin University, Shanghai Jiao Tong University, Tsinghua University, Shanghai Institute ofMicrosystem and Information Technology and etc. Recently the main researches are 1×2 and2×2 micro-mechanical optical switches. We have got a lot of achievements, for the reasonsof not enough research devotions, there is a long way at product quantity, performance toprice and application compared with abroad. In this paper, 2×2 micro-mechanical optical switches is fabricated, which changes inputlight spread direction by moving reflective micromirror. The optical switches includereflective micromirror, self-aligned optical fiber grooves and actuator structure. Reflectivemicromirror, optical fiber grooves and top electrode of static electricity driven torsion beamstructure are fabricated on (100) silicon wafer (or (110) silicon wafer). The fabricationprocess is simple, reflective micromirror and optical fiber grooves are fabricated in KOHsolution through once mask, and counter electrode of actuator is made of another siliconwafer. The insertion loss of optical switches has been analyzed by principle of single modeoptical connecting loss, the main reasons which cause insertion loss in the cross state arethe excursion brought by the axes, radial and angle of two connected optical fibers. Thereasons which cause insertion loss on reflective state include the loss of two optical fibersconnect, surface roughness and width of reflective mirror. When the insertion loss is lessthan 2dB on reflective state, the coupling between two common single mode optical fibers isquite difficult, so doing some special treatment to the fibers are necessary. 110吉林大学博士学位论文 The relationship between driven voltage and structure dimension of cantilever structureand torsion beam with common plane counter electrode is analyzed. The actuator with theslant counter electrode was proposed. Theoretical analysis indicates that the pull-in voltagebased on the slant counter electrode actuator is half of that based on the plane counterelectrode. The switching time of slant counter electrode actuator is calculated. The technology conditions of fabricating optical switches are decided, and the crystaldirection alignment pattern is designed and fabricated. The reflective micromirrors,the optical fiber grooves and the top electrode of torsion beam actuator are fabricated on(100) and (110) silicon wafers. The slant counter electrode is fabricated using tilted 2.5°(111) silicon wafer. By five-dimensions optical fiber adjusting frame, measuringmicroscope and other device, the micro-mechanical optical switches are assembled, the topelectrode and counter electrode are adhered together, and the optical fibers are fixed ingrooves. The pull-in voltage is 35.7V, the switching time from across state to reflective state andfrom reflective state to cross state are less than or equal 5ms, and the lifetime is more than107 cycle. The deviation is caused by the tolerance between the fabrication and the design.The insertion loss and crosstalk of optical switch are measured using s...