Design and fabrication of multilayr thin film 3D optical planar circuit using birefringence

在本研究中，通过多层薄膜结构实现TE和TM板模传播常数的广泛分离，基于光学平面电路理论分析了单模工作或保偏工作的三维光波导。制作了相应的三维光波导，进行了测量，并与分析结果进行了比较。同时，作为二维平面光电路横向约束光场的基础研究，对大弯曲角弯管、大分支角Y支路和圆形弯管等简单光电路进行了分析和实验。得到了以下初步结果。(1)采用TiO2/SiO2构建多层薄膜板状波导，10层足以实现充分的TE-TM模式分离，计算和实验也证实了这一点。(2)此时的损耗在TM模式下测量为1.6 db /cm，在TE模式下测量为3dB/cm。(3)对于三维光波导的分析，假设上下金属边界在合适的位置，TE和TM大约需要25个高度模式来实现切向场分量的连续性。(4)对于多层三维光波导，0.3mu厚度可以单模工作，0.6mu厚度可以多模工作，阶梯形侧约束，肋型侧约束再次使该结构单模工作。(5)对多层结构介质条加载三维光波导进行了理论分析。由于电场的exp衰减，介质厚度的影响随厚度而饱和。(6)利用上述结构，根据几何光学原理估算出最大弯曲角度。实验证实了这一结果。(7)对非对称结构的肋型多层三维光波导进行了理论分析，其中两侧的层数分别控制。得到了有趣的结果。(8)指出采用上述结构的平行耦合光波导可以广泛地控制耦合强度。计算了平行耦合波导的传播常数，证实了强耦合的存在。(9)此外，必须注意的是，强约束三维光波导不连续的场分析和相应的实验与多层光波导的研究是并行进行的。少

In this research, wide separation of TE and TM slab-mode propagation constant being realized by multilayred thin-film structure, three dimentional (3D) optical wave guides, where single mode operation or polarization-maintaining operation are expected, are analyzed based on optical planar circuittheory. The corresponding 3D optical waveguides are fabricated, measured and compared with the analytical results. Also as a basic research for optical planar circuit with 2D pattern to confined the optical field laterally, simple optical circuit such as bend with large bend angle, Y branch line with large branching angle and circular bend are analyzed and experimented. Following results, still preliminary, are obtained.(1) Multilayred thin-film slab waveguide being constructed by TiO2/SiO2,10 layrs are enough for sufficient TE-TM mode separation, which is also confirmed by calculation and experiment.(2) Loss at this time is measured to be l. 6dB/cm for TM mode and 3dB/cm for TE mode.(3) As for … More the analysis of 3D optical waveguide, supposing the top and bottom metal boundary at the proper position, about 25 height modes of TE and TM are necessary to realize the continuity of the tangential field components.(4) As for multilayred 3D optical wave guide, single mode operation is possible for 0.3mu thickness but multi mode operation for 0.6mu with step-type side-confinement, Rib-type side-confinement again makes this structure single mode operation.(5) Dielectric strip loaded 3D optical waveguide with multilayred structure is analyzed theoretically.Effect of the dielectric thickness is saturaed with thickness because of exp decay of the field.(6) Using the above structure, maximum bend angle is estimated based on geometrical optics. This result is confirmed by experiment.(7) Rib-type multilayred 3D optical waveguide with asymmetrical structure is analyzed theoretically, where number of layrs at both side are controlled separately. Interesting results are obtaind.(8) It is pointed out that parallel coupled optical waveguide using above structure can control the coupling strength widely. Propagation constant of the parallel coupled waveguides is calculated, which confirms the existence of strong coupling.(9) In addition, it must be noted that field analysis of the strongly confined 3D optical waveguide discontinuity and thecorresponding experiment has beeen carried out in parallel with the research of the multilayred optical waveguide. Less