Leveraging Digital Twin Technologies: All-Photonics Networks-as-a-Service for Data Center Xchange in the Era of AI [Invited Tutorial]. - Hideki Nishizawa; Kazuya Anazawa; Tetsuro Inui; Toru Mano; Takeo Sasai; Giacomo Borraccini; Tatsuya Matsumura; Hiroyuki Ishihara; Sae Kojima; Yoshiaki Sone; Koichi Takasugi (CoRR, 2026)