Polarization Independent Electro-optic Modulator Based On Photonic Crystal

As optical communication enters the 5G era,the requirements for communication capacity and communication speed are also increasing.In the field of silicon-based optoelectronics,research into electro-optical modulators with higher performance and smaller dimensions has become a hot topic.However,at present,most electro-optic modulation devices have polarization related problems,polarisation correlation can lead to polarisation losses and reduced performance of the modulator.Solving the problem of polarization sensitivity can effectively improve the performance of the modulator,so the study of polarization independent modulator is of great significance.In this paper,a photonic crystal polarization independent modulator based on mode conversion is proposed.The device is located in the center of silica cladding and consists of three parts:polarization beam splitting device,polarization rotation device and photonic crystal modulator.The light with two different polarization modes enters the modulation region.Before entering the modulation region,the polarized light converted into the same mode through polarization beam splitting and polarization rotation devices enters the modulation region.The modulation region uses an electro-optic modulator based on one-dimensional photonic crystal nano beam cavity.By changing the parameters of the cavity,the photonic crystal generates a photonic band gap to better localize the beam in the photonic crystal.Using the defect mode migration theory,a p-n junction is formed by doping the resonant cavity and applying an applied voltage to change the refractive index of the material at the resonant cavity to cause the resonant wavelength to migrate,so as to realize the on-off modulation of the optical signal.The device’s optical and electrical structural models are simulated using lumerical software to optimize its structural parameters for optimal performance,and the results show that the device is capable of modulating on and off for TE₀ and TM₀ mode incident light signals at 1554.7 nm,with extinction ratio of 16.2 d B,insertion loss of 0.8 d B,modulation depth of 0.97,modulation voltage of 1.32 V and modulation rate of 14.3 GHz.The integrated device can adapt to the trend of optoelectronic integration and has important application value in optical communication and optical interconnection technology in the future.