Micro-Grating Array-Enabled Power Efficiency Improvement for a DMD-Based Optical Switch

Digital micro-mirror device (DMD)-based optical switch can dynamically change the channels reallocation and provide flexibility in optical networking with the advantages of fast time response and scalable port number. However, the DMD as a binary diffraction device has a limited efficiency of 10.1% at the +1st diffraction order. Here we propose and demonstrate a DMD-based optical switch with improved efficiency enabled by a blazed micro-grating array. The blazed micro-grating array is designed and fabricated to diffract and make use of the wasted -1st order beams of the DMD. Using this device, we achieve ~2 dB efficiency improvements for a $2\times 2$ optical switch with all switching states. We experimentally demonstrate high speed switching of channels carrying 15 and 30 Gb/s ON-OFF keying signals. The micro-grating array has the potential to develop for the DMD-based optical switch with multiple channels.