ECE 5212 L2, 0906, 2016 UConn, F. Jain One dimensional wave guiding, Pages 28-38-82 Two dimensional wave guiding: effective index method p. 50 Directional couplers and dual channel electro optic modulator based on directional couplers

Fig. 1. Cross sectional schematic of a three-slab waveguide. TE Modes Fig. 1. Cross sectional schematic of a three-slab waveguide.

15. This k should be written as Greek k

Overview of Optical Modulators ECE 5212 L2 Directional Couplers, Optical Modulators, 0906, 2016 UConn, F. Jain Overview of Optical Modulators Pages 81-82 Typical dual channel electro optic modulator based on directional couplers 1 2 V1 V2 (a) Substrate electrode (cross-sectional) V (b) Three electrode configuration (cross sectional schematic)

Mach-Zehnder modulator: It does not use optical tunneling like directional couplers but uses interference effect. The incident beam is divided into two paths and one path’s index of refraction is changed using electro-optic effect. This results in change in the phase of the propagating signal.

Bragg modulators: Electro-optic grating: It works on diffraction of incident beam by an electro-optic grating. Acousto-optic grating. Here a surface acoustic wave is launched that sets up a grating which diffracts the incident wave coupled from the left end.

Directional Coupler Equations Two sets of derivations: --one intensive and detailed (pages 71-76 leading to Eqs. 12 and 13. It solves for A(z) and B(z) coefficients (Eqs. 18 page 77) that defines the electric field in two waveguides. Also full power and no power transfer condition Eq. 22 on page 78. The important equation is 25 and 26 (page 79) which determine the coupling length and relate it to index of refraction change. -- Other overview starts from page 85 (Hunsperger material)