The 2nd International Conference on Optical and Terahertz Communications and Future Networks (OTCN 2026) will be held in Singapore, from September 11-13, 2026 (hybrid both in person and online). Building on the success of the first edition held in Japan, OTCN 2026 will continue to bring together leading researchers, engineers, industry experts, and innovators from across the globe to share groundbreaking work and foster collaboration in optical and terahertz communications, future network systems, and emerging applications. We warmly invite submissions worldwide to shape the future of communication technologies.