Development of 1 x 16 Thermo-optic MZI Switch Using Mullimode Interference Coupler

A 1x16 thermo-optic switch with small excess loss using multimode interference(MMI) couplers is designed, fabricated, and measured. This paper introduces the proposed 1x16 thermo-optic switch, and discusses the measurement results. The 1x16 thermo-optic switch is formed as 4-stage which consists of 15 unit devices. The unit devices are the 2x2 thermo-optic switches with Mach-Zehnder interferometer(MZI) structure. The characteristics of the 1x16 thermo-optic switch depends strongly on each unit device. The unit deviceconsists of two 3-dB general interference MMI couplers and two single mode waveguide arms as a phase shifter. First of all, the 3-dB optical splitter and 2x2 MZI thermo-optic switch have been tested to confirm the characteristics of the unit devices of the 1x16 MZI thermo-optic switch. Using the measurement results of the unit devices, the 1x16 MZI thermo-optic switch can be produced with better characteristics. The resultant structure of the MMI coupler with the optical light source of wavelength of 1550nm for the 1x16 thermo-optic switch is that the width and the optimized length are 25 mu m and 1580 mu m, respectively. The smallest excess loss for the unit device is -0.5dB and the average excess loss is -0.7dB.