改善多层电光聚合物调制器直流弛豫的一种简单方法的分析与模拟(英文)

ANALYSIS AND SIMULATION OF A SIMPLE WAY TO OPTIMIZE DC FIELD RELAXATION IN MULTI-LAYER ELECTRO-OPTIC POLYMER MODULATORS

电场分布和直流漂移对多层电光聚合物调制器的器件稳定性和极化效率有着重要的影响 .本文由电磁场理论建立出等效电路模型 ,分析结果表明多层聚合物调制器的稳态直流场分布取决于材料的电特性 ;材料的弛豫时间常数τ(τ=ε/σ2 ,其中σ是电导率 ,ε是介电常数 )是最大程度上消除直流场弛豫的关键 .当外加直流电压时 ,波导层的场分布由初态到稳态指数变化 ,这一过程由波导层和覆盖层的弛豫时间差决定 .当两者相差为零时 ,弛豫消失 .但在实际工艺中很难作到这一点 ,为此 ,本文经过分析、模拟 ,提出一种简单的“自抑制”机制 ,能够很好地改善多层电光聚合物调制器设计中的直流漂移问题 .

Electric field distribution and DC drift in a multi layer electro optic (EO) polymermodulator play important roles in device stability and polarization efficiency.Based on an equivalent circuit model of electromagnetic theory,analytical results show that steady state DC field distribution on multi layer polymer modulator depends on the electrical properties of the materials.And the polymer material′s relaxation time constant τ(τ=ε/σ,where σ and ε are the conductivity and the dielectric constant respectively) is proved to be the key point in maximally eliminating the DC field relaxation on the active guiding layer.When a step DC voltage is applied to the electrodes,field across the waveguide layers will relax exponentially from an initial state to a steady state depending on the difference between the dielectric material relaxation times of the guiding and cladding layers.To entirely eliminate the DC field relaxation,the relaxation time of the three layers must be equal at the operating conditions.However,in real devices,they can not be absolutely equal.After further analysis and simulation,we have found that if the dielectric relaxation time difference between the upper layer and the active layer is the same as that between the lower layer and the active layer,but in the opposite direction,the DC field drift in the active waveguide layer would be significantly reduced.That works like a “self constrained” mechanism.Thus,we suggest a simple way to achieve a more stable DC bias in multi layer EO polymer modulator design.