Research On Thermal And Mechanical Properties And Optimization Design Of Thermal Optical Waveguide Switch In MEMS

All optical network plays an significant part in modern informational society.Ituses the optical switch instead of the existed electric network switch, which can highlyincrease the efficiency of information transmission. Optical switch is one of the mostessential devices that help fulfill the all optical network. This dissertation studies thethermal and mechanical properties of plain wave thermal-optical switch and analyzeshow the material property and the device structure of the thermal-optical switchinfluences its performances.This paper gives the thermal-elastic coupling equation with heat delay time inmicro-structure. By simulating the thermal elastic vibration in micro-structure, it studythe factors influencing the beam amplitude, which illustrating the good applicability ofgeneralized thermoelastic theory in the micro mechanical heat transfer. The way howmaterial coefficient and core structure influence the power consumption and responsetime will be studied using Non Fourier heat transfer theory, explaining the advantage ofthe mixed waveguide optical switch in response speed. Considering the stack of thetemperature caused by reflection of the thermal wave on the boundary layer andwaveguide device interface reflection, the average temperatures of the core layer withdifferent core layer shape and heat delay time is compared. Combining previous work instructural design, the structure with vacuum isolation on both sides and the thermalinsulation layer made in polymer is designed: these two kinds of structure can reducethe power consumption without deep influence of response time.The thermal mismatch caused by the great difference among the materialparameters of the SiO2and organic polymer in the mixed wave thermal-optical switchhave hidden trouble stability of the structure. This paper studies the curvature and theenergy release rate of interface trap in the SOI-SU and PMMA-SU. According to thestructural characteristics and working principle of thermal waveguide optical switch, thebeam-membrane model is developed based on the existing plate-membrane model andthe curvature of the structure is analysised, illustrating the advantages of the new model.Then the energy release rate of interface defects is calculated: obtaining KIusingthermal coupling equations and the stress intensity factor extrapolation; obtaining KIIincombination with the simplified model of mechanics for crack propagation.Thus energy release rate of interface defects is concluded. The reference for the stability of theoptical switch design is provided by comparing interface fracture work of the similarstructure.