摘要
针对多通道一维光子晶体滤波器不易精确调谐的问题,设计了一种以BaTiO_(3)材料为缺陷层的光子晶体双通道滤波器,通过分别改变两层BaTiO_(3)的外置电压来调节材料的折射率,从而实现双通道频率精确调谐,并引入遗传算法提高调谐效率。模拟结果表明:遗传算法在保证透射峰的透射率大于78%的条件下,可以在400代左右的计算进程中给出符合滤波目标的调谐电压组合;利用传输矩阵计算得出的分布曲面与拟合调谐函数对遗传算法给出的电压数据进行验证,证明了遗传算法的准确性与高效性。所设计的滤波器也可通过调节空气层厚度,实现双通道在(S,L)、(E,C)和(C,L)等波段的跨越式调谐。遗传算法的引入使得所设计模型易于实现调谐程序的自动化,可为微纳米滤波器的设计与调谐应用提供一定的参考。
Objective Photonic crystal filters can greatly increase the transmission capacity of optical communication systems,which is a research hotspot for optical wavelength division multiplexing technology.Tunable optical filters are key components in optical wavelength division multiplexing systems.A monotonic functional relationship can easily be formed between the transmission peak wavelength of a single channel filter and tuning parameters to help achieve precise tuning.However,the information capacity of this filter is limited.The coupling relationship between dual-channel or even multi-channel filtering structures and transmission peak wavelength is complex.The overall translation of multi-channel transmission peaks is mainly focused on current research and lacks discussion on precise tuning.We design a tunable dual-channel filter based on BaTiO3(BTO)defect layers and introduce a genetic algorithm to achieve precise tuning of dual channels.This onedimensional photonic crystal filter changes the refractive index of BTO by altering applied voltages,thereby achieving separate tuning of dual transmission peak positions.Purposeful genetic algorithms can both automatically find peaks and ensure transmissivity,relying on computer computing power to realize automatic tuning of filtering wavelengths.Methods By adopting the transfer matrix theory,transmission spectra of the filter are obtained,and surface functions of two transmission peaks with the variation of two voltages are fitted.By combining surface projection with surface functions,precise tuning of the positions of two transmission peaks can be achieved.Meanwhile,a genetic algorithm is also introduced to achieve automatic tuning.By employing an algorithm framework based on purposes,the program can automatically find voltage combinations that match target peaks,thus avoiding manual involvement in analyzing surfaces and functions.Additionally,the tuning process can be simplified,and efficiency can be improved with the help of computing power.Results and Discussions Structural parameters of the crystal filter are analyzed.Fig.3 shows that when the period number is set to be 4,the requirements of wavelength division multiplexing can be met,and the overall size of the structure is also reduced.Meanwhile,when the voltage difference between two external voltages is less than 50 V,a transmissivity over 78%can be ensured to satisfy the filtering requirements(Fig.4).By changing the thickness of the air layer in the middle of the filter,filtering can also be switched between bands such as(S,L),(E,C),and(C,L)(Fig.5).By conducting surface fitting,we find that the tunable ranges of the two transmission peaks are 1499‒1533 nm and 1572‒1615 nm respectively.The specific relationship between the position wavelengths of two transmission peaks and the voltages are shown in Eqs.(8)and(9).Traditional methods require precise tuning of the positions of two transmission peaks by curved surface projection.We take a transmission peak fixed at 1510 nm as an example and obtain a tunable function for the other transmission peak[Eq.(11)].By combining Eq.(10),the corresponding external voltage combination can be obtained.In selecting an appropriate fitness function[Eq.(13)]with a crossover rate of 0.6 and a mutation rate of 0.4,the genetic algorithm can autonomously search for external voltage combinations that match the target transmission peaks about an average of 400 generations.Additionally,we test the convergence performance of genetic algorithms for tuning three target wavelengths,including(1510 nm,1588 nm),(1515 nm,1595 nm),and(1520 nm,1599 nm).Fig.9 shows that when the target wavelengths are(1510 nm,1588 nm),the transmissivity of both peaks is higher than 94%with a convergence generation of 416 generations.Fig.10 shows that when the target wavelengths are(1515 nm,1595 nm)and(1520 nm,1599 nm),the transmissivity is higher than 92%and 97%respectively,with convergence generations of 373 and 395 generations.Due to the avoidance of relatively complex manual analysis processes,genetic algorithms can improve tuning efficiency with the help of computer computing power.Conclusions We design a photonic crystal dual-channel filter based on BTO defect layer.A genetic algorithm is introduced into the filter tuning for efficient and fast dual-channel simultaneous accurate filtering.The convergence performance of the genetic algorithm for tuning three target wavelengths is tested,including(1510 nm,1588 nm),(1515 nm,1595 nm),and(1520 nm,1599 nm).The voltage combinations for the above target wavelengths with transmissivity greater than 90%are obtained,and their convergence generations are 416,373,and 395 respectively.Similar calculations also indicate that genetic algorithms can converge within an average of 400 generations.By comparing and validating the above data using distribution surfaces and fitting tuning functions,we demonstrate the accuracy and efficiency of genetic algorithms in tuning.Meanwhile,the designed filter can also achieve dual-channel step tuning in the(S,L),(E,C),and(C,L)bands by changing the thickness of the intermediate air layer.Finally,our study will provide references for the design and application of photonic crystal filters.
作者
王海燕
张明达
费宏明
曹斌照
刘欣
杨毅彪
Wang Haiyan;Zhang Mingda;Fei Hongming;Cao Binzhao;Liu Xin;Yang Yibiao(College of Physics,Taiyuan University of Technology,Taiyuan 030024,Shanxi,China;College of Electronic Information and Optical Engineering,Taiyuan University of Technology,Taiyuan 030024,Shanxi,China;Key Laboratory of Advanced Transducers and Intelligent Control System,Ministry of Education,Taiyuan University of Technology,Taiyuan 030024,Shanxi,China)
出处
《光学学报》
EI
CAS
CSCD
北大核心
2024年第11期196-204,共9页
Acta Optica Sinica
基金
国家自然科学基金(11704275,62175178,U22A20258)
国家自然科学基金青年科学基金(11904255)。
关键词
光学设计
滤波器
遗传算法
精准调谐
光子晶体
传输矩阵
optical design
filter
genetic algorithm
precision tuning
photonic crystal
transmission matrix
