Terahertz flip-mode via 3D printed π-step phase plate - Alaba, Kenneth Jay; Verona, Ivan Cedrick; Fernandez, Kristiene Joy; Arcilla, Jose Mari Sebastian; Dela Rosa, Lourdes Nicole; Bardolaza, Hannah R.; Stantchev, Rayko Ivanov; Hermosa, Nathaniel P.; Estacio, Elmer S. (Proceedings of the Samahang Pisika ng Pilipinas, 2025)