Planar and channel waveguides on Na:CBN formed by oxygen ion implantation

We reported the fabrication of the planar and channel waveguides in Na-doped calcium barium niobate (CBN) with multiple-energy oxygen-ion implantation. Multiple-energy implants can broaden the barrier width to reduce light leakage from the waveguide to the substrate through the barrier wall. The guiding modes and the near-field intensity distribution of the light were measured by the prism-coupling method and the end-facing coupling arrangement separately. The refractive index profiles of planar and channel waveguides were both typical “well + barrier” distribution, and we used the finite-difference beam propagation method (FD-BPM) to simulate the light propagation. After annealing at 200 °C for 30 min, the waveguide propagation loss of the planar and channel waveguides could be reduced down to ∼3.7 dB/cm and ∼3.5 dB/cm. The calculated results were in excellent agreement with the measured waveguide modes, indicating the feasibility of designing these devices.