Silicon-on-insulator free-carrier injection modulators for the mid-infrared

Experimental demonstrations of silicon-on-insulator waveguide-based free-carrier effect modulators operating at 3.8 mu m are presented. PIN diodes are used to inject carriers into the waveguides, and are configured to (a) use free-carrier electmabsorption to create a variable optical attenuator with 34 dB modulation depth and (b) use free-carrier electrorefraction with the PIN diodes acting as phase shifters in a Mach-Zehnder interferometer, achieving a V pi L pi of 0.052 V. mm and a DC modulation depth of 22 dB. Modulation is demonstrated at data rates up to 125 Mbit/s. Published by The Optical Society under the terms of the Creative Commons Attribution 4.0 License.