| dc.description.abstract | Silicon-on-insulator (SOI) waveguides have received much attention as a platform for planar lightwave circuits (PLCs) due to their compatibility with complementary metal oxide semiconductor (CMOS) technologies. Light in the silicon layer of SOI is naturally confined in the vertical direction because of the high index contrast between the bottom oxide layer, Si layer, and air. However, owing to the inherently large index contrast between si and air, the core size of a single-mode SOI waveguide is generally less than sub-micro size, resulting in a very serious coupling problem.
Rib waveguide with specific structure can provide a core width with large cross-section, but still maintain in single-mode operation. In this paper, a large single-mode rib waveguide is designed and demonstrated. For easily coupling to SMF, the upper silicon layer is chosen to 10 μm, and the corresponding width of core is 6 μm with etching depth equal to 3.5 μm. On the basis of the above design, a calculation results of a butt-joint interconnect from SMF can be as high as -1.25 dB. The polarization-dependence loss is less than 0.01 dB, and wavelength- dependent loss preserves 1 dB variation within 100 nm.
For the purpose of high-density integration in PLC, a phase- compensated air-based microprism is introduced to a wide-angle bending rib waveguide. An air microprism, which can be made by directly dry etching up to oxide layer, compensates the phase difference in this rib waveguide bend, and then properly tilts the planar wavefront to the designed bending angle. A 10° bending waveguide with radius of curvature of only 27.1 μm is designed and fabricated.
In the last section of this paper, a monolithic integration of guide-mode resonance (GMR) filter and rib waveguide is proposed and analyzed. This GMR with structure of grating and waveguide can be directly fabricated by dry-etching process on the top Si layer of SOI. A 1310/1550 nm filter by this monolithic structure is designed. Strong modulation in the grating structure with two-filling factor design can enlarge the operating wavelength window to more than 40 nm, which can avoid general wavelength shift by temperature variation. | en_US |