工作波长为1050 nm高透亚波长光栅的设计

Design of 1050 nm High Transmission Sub-wavelength Grating

高透射性的亚波长光栅可扩大微机电可调谐垂直腔面发射激光器的波长调谐范围,而使波长调谐范围达到最优,就需要亚波长光栅的透射率最大,这需要优化光栅参数。利用严格耦合波方法,结合遗传算法,设计了一种1050 nm波长亚波长光栅结构。计算分析得出:对于TE偏振,在光栅周期为204 nm、占宽比为0.19、槽深为142 nm的结构参数下,透射率可高达99.99%;对于TM偏振,在周期为169 nm、占宽比为0.72、槽深为138 nm的结构参数下,透射率可高达99.99%。通过分析结构参数对光栅透射率的影响,证明该光栅结构对周期、占宽比、槽深具有优良的工艺容差。该设计方法的运用简单快速,能够避免陷入局部最优,且具有较强的通用性,可为其他类似光栅的优化设计提供借鉴。

The high transmission sub-wavelength grating can improve the wavelength tuning range of micro-electromechanical tunable vertical cavity surface emitting lasers.To achieve the optimal wavelength tuning range,it is necessary to maximize the transmission of the sub-wavelength grating,which requires optimizing the grating parameters.Using the method of rigorous coupled wave and genetic algorithm,a sub-wavelength grating structure with a wavelength of 1050 nm was designed.The calculation and analysis show that:for TE polarization,the transmittance can be as high as 99.99%under the structural parameters of a grating period of 204 nm,a duty cycle of 0.19 and a groove depth of 142 nm;for TM polarization,at a period of 169 nm,a duty cycle of 0.72 and a groove depth of 138 nm,the transmittance can be as high as 99.99%.By analyzing the influence of the structure parameters on the transmittance of the grating,it is proved that the grating structure has good process tolerance for the period,duty cycle and the groove depth.This design method is simple and fast.It can avoid falling into local optimum and have strong generality,which can provide reference for the optimal design of other similar gratings.