  Inter-orbital coupling refers to the possibility of exciting orbital states
by otherwise orthogonal non-interacting modes, a forbidden process in photonic
lattices due to an intrinsic propagation constant detuning. In this work, using
a femtosecond laser writing technique, we experimentally demonstrate that
fundamental and excited orbital states can couple each other when located at
different spatial positions. We perform a full characterization of an
asymmetric double-well like potential and implement a scan method to
effectively map the dynamics along the propagation coordinate. Our fundamental
observation constitutes also a direct solution for a spatial mode converter
device, which could be located in any position inside a photonic glass chip. By
taking advantage of the phase structure of higher-order photonic modes and the
effective negative coupling generated, we propose a trimer configuration as a
phase beam splitter ($\pi$-BS), which could be of great relevance for
multiplexing and interference-based photonic concatenated operations.
