High-dimensional communication on etchless lithium niobate platform with photonic bound states in the continuum

Photonic bound states in the continuum (BICs) have been exploited in various systems and found numerous applications. Here, we investigate high-order BICs and apply BICs on an integrated photonic platform to high-dimensional optical communication. A four-channel TM mode (de)multiplexer using different orders of BICs on an etchless lithium niobate (LiNbO3) platform where waveguides are constructed by a low-refractive-index material on a high-refractive-index substrate is demonstrated. Low propagation loss of the TM modes in different orders and phase-matching conditions for efficient excitation of the high-order TM modes are simultaneously achieved. A chip consisting of four-channel mode (de)multiplexers was fabricated and measured with data transmission at 40Gbps/channel. All the channels have insertion loss <4.0dB and crosstalk <-9.5dB in a 70-nm wavelength band. Therefore, the demonstrated mode (de)multiplexing and high-dimensional communication on LiNbO3 platform can meet the increasing demand for high capacity in on-chip optical communication. Here, the authors investigate high-order bound states in the continuum and apply them on an integrated photonic platform for high-dimensional optical communication. The demonstrated mode (de)multiplexing and high-dimensional communication can enhance the data capacity with low insertion loss and crosstalk.