1. EE16.468/16.568Lecture 3Waveguide photonic devices 1. Mach-Zehnder EO modulator Electro-optic effect, n2 changes with E -field a1 a2 a3 b1 b2 50% AA out b3 n2 n

2. EE16.468/16.568Lecture 3Waveguide photonic devices Switches High power modulators Filters Network configuration Dynamic routing data traffic Provide high-speed data stream for shared users Reduce noise 2. Optical Switches

3. EE16.468/16.568Lecture 3Waveguide photonic devices Types of Optical Switches Hard for switch array Hard for alignment Reliability issues 1. Micro-electro-mechanical systems (MEMS) Disadvantages: From Lucent, Bell lab

4. EE16.468/16.568Lecture 3Waveguide photonic devices Free space based, hard to integration Hard for alignment Large size 2. Liquid crystal based optical switch Disadvantages:

5. EE16.468/16.568Lecture 3Waveguide photonic devices 3. Thermo-optic switch, directional coupler based Wavelength sensitive Large size for switch array Disadvantages: P1P1 P 2 P2P2 P 0 =1 L Coupler TO switch Heater Input waveguide output waveguides

6. EE16.468/16.568Lecture 3Waveguide photonic devices 4. Thermo-optic switch, total internal reflection based n1n1 n2n2

7. EE16.468/16.568Lecture 3Waveguide photonic devices Advantages of TIR based thermo-optic switch Easy array operation Wavelength insensitive TIR TO switch array

8. EE16.468/16.568Lecture 3Waveguide photonic devices 2x2 thermo-optic switch and 8x8 switch arrays 2 optical chips, each with an array of 8x8 optical switches Input Wavegui des Output Wavegui des Electrod e Pads

9. EE16.468/16.568Lecture 3Waveguide photonic devices Device performance

10. EE16.468/16.568Lecture 3Waveguide photonic devices 5. Resonator based EO optical switch

11. EE16.468/16.568Lecture 3Waveguide photonic devices 5. Resonator based EO optical switch array Easy scale up to NxN arrayt Low power consumption, high yield and high reliability Very compact size

12. EE16.468/16.568Lecture 3Waveguide photonic devices Wavelength division multiplexing (WDM) technology

13. EE16.468/16.568Lecture 3Waveguide photonic devices Coarse Wavelength-division Multiplexing (CWDM) Dense Wavelength-division Multiplexing (DWDM)

14. EE16.468/16.568Lecture 3Waveguide photonic devices 3. Array waveguide grating (AWG)

15. EE16.468/16.568Lecture 3Waveguide photonic devices 3. Array waveguide grating (AWG) L0L0 L 0 +(m-1)  L Center channel Nc: index in channel ns

16. EE16.468/16.568Lecture 3Waveguide photonic devices 3. Array waveguide grating (AWG) L0L0 L 0 +(m-1)  L Upper one channel: f D D d L 0 +(m-1)  L – (D/f)(m-1)d