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

在本研究中，利用多层薄膜结构实现TE和TM板条模传输常数的大范围分离，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，对其进行了测量，并与分析结果进行了比较。作为二维图形平面光路横向限制光场的基础研究，对大弯角弯曲、大分支角Y分支线和圆形弯曲等简单光路进行了分析和实验。得到了如下初步结果：(1)由二氧化钛/二氧化硅构成的多层薄膜平板光波导足以实现充分的TE-TM模分离，这一点也得到了计算和实验的证实。(2)此时的损耗为L，TM模为6db/cm，TE模为3db/cm。(3)对于…而言对三维光波导作了进一步的分析，假设上下金属边界在适当的位置，要实现切向场分量的连续，大约需要25个TE模和TM模。(4)对于多层3D光波导而言，对于0.3微米厚的多层光波导而言，可以实现0.3微米厚的单模运转，而对于0.6微米的阶梯型侧向限制，可以实现0.6微米的多模运转。从理论上分析了介质条加载的多层结构的三维光波导，由于场强的经验衰减，介质厚度的影响随厚度饱和。(6)利用上述结构，基于几何光学理论估算了最大弯曲角。从理论上分析了不对称结构的脊形多层三维光波导，其中两侧层数分别进行了控制。得出了一些有趣的结果。(8)指出采用上述结构的并行耦合光波导能很好地控制耦合强度。计算了平行耦合光波导的传输常数，证实了强耦合的存在。(9)另外，必须注意的是，强受限三维光波导不连续性的场分析和相应的实验是与多层光波导的研究并行进行的。较少

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