Optical I/O

摘要: In this chapter, we describe the design of these two types optical input/output coupling techniques: fibre grating couplers in Section 5.2, and edge 5.3. A method creating a mask layout for focusing coupler is presented. Methods polarization management are also discussed 5.4. The challenge to silicon photonic chips Owing large refractive index contrast between core ( n = 3.47 at 1550 nm) dioxide cladding 1.444 nm), propagation modes highly confined within waveguide with dimensions on order few hundred nanometers (see Sections 3.1 3.2). Although benefit large-scale integration, small feature size raises problem huge mismatch mode an waveguide. cross-sectional area (with diameter 9°m) almost 600 times larger than that 500 nm × 220 hence requires components adjust mode-field accordingly. Several approaches have been demonstrated tackle aforementioned mismatch. Edge using spot-size converters lensed fibres one solution used address this, high-efficiency insertion loss below 0.5 dB has [1]. addition, both TE TM polarizations can be efficiently coupled. However, approach only chips, implementation such designs complicated post-processes high-resolution alignment, which increase packaging cost. Grating alternative issue Compared coupling, several advantages: alignment during measurement much easier couplers; fabrication does not require post-processing, reduces cost; put anywhere chip, provides flexibility as well enabling wafer-scale automated testing.