Experimental Observation of Interorbital Coupling

Interorbital coupling refers to the possibility of exciting orbital states by otherwise orthogonal noninteracting modes, a forbidden process in photonic lattices due to intrinsic propagation constant detuning. In this Letter, using a femtosecond (fs) 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 also constitutes 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, which could be of great relevance for multiplexing and interference-based photonic concatenated operations.

Automated summary

In this study, interorbital coupling is experimentally demonstrated using femtosecond laser writing technique, showing that fundamental and excited orbital states can be coupled at different spatial positions. A solution for a spatial mode converter device is proposed, and a trimer configuration is suggested as a phase beam splitter for multiplexing and interference-based photonic concatenated operations.