Based On Lithium Niobate <sub> 3 </ Sub> 1 ¡Á 2y Branch Digital Optical Switch Design

With the development of optical network and optical communication,optical switch and optical switch array is playing a more and more important role.The digital optical switch(DOS)has become a very attractive component for space switching in multi-wavelength optical communication system applications.Its step-like switch response to applied voltage makes the DOS highly insensitive to wavelength, polarization,refractive index,temperature,and other physical parameters that may affect switching characteristic.Because of its low crosstalk,high extinction ratio,low insert loss,low driving voltage and independence of polarization,the digital optical switch will become a competitive optical switching device.Due to its high electro-optic coefficient and acousto-optic coefficient,ease of fabricating and its environmental stability,LiNbO₃ has been used in optical devices extensively.In this paper,we computed and found the main parameter for facture of Ti: LiNbO₃ waveguide according to the function of Ti diffusion profile in LiNbO₃ and the waveguide mode's cut-off condition.The parameters include waveguide width:7μm, diffusion temperature:1050℃and diffusion time:9～10h.From the experiment result, we prove that when the waveguide width is 7μm,the output of light field is single mode.With the purpose of designing Y branch DOS integrated with S-bend VOA,we designed the structure of S-bend VOA,1×2Y branch DOS and 1×2Y branch DOS integrated with S-bend VOA.Simulation was based on BPM,the Y branch angle was 0.15 degree,S-bend waveguide width was 5μm and asymmetrical electrodes were used,the crosstalk of the DOS we designed is -30dB when a voltage 6v was applied; Then experiment was carried out to realize the S-bend VOA,1×2Y branch DOS and 1×2Y branch DOS integrated with a S-bend VOA,and the result proved that our design was available.The attenuation of VOA was about 27dB when a negative voltage 18.5V was applied;The crosstalk of 1×2Y branch DOS was about 24dB,and its two switch states driving voltage were 15.4V and -14V;In the end,lower driving voltage was achieved in 1×2Y branch DOS integrated with S-bend VOA,that is 12.4V and -12.6V,and the crosstalk is about 23dB.