Planar optical waveguides in Bi₄Ge₃O₁₂ crystal fabricated by swift heavy-ion irradiation

We report on the fabrication of the planar waveguides in the Bi₄Ge₃O₁₂ crystal by using 17 MeV C⁵⁺ or O⁵⁺ ions at a fluence of 2×10¹⁴ ions/cm². The reconstructed refractive index profiles of the waveguides produced by either C⁵⁺ or O⁵⁺ irradiation are the “well” + “barrier” pattern distribution. The two-dimensional modal profiles of the planar waveguides, measured by using the end-coupling arrangement, are in good agreement with the simulated modal distributions. After thermal annealing treatment at 260°C for 30 min, the propagation loss for C⁵⁺ and O⁵⁺ irradiated waveguides could be reduced down to ~1.1 dB/cm and ~4.8 dB/cm, respectively, which exhibit acceptable guiding qualities for potential applications in integrated optics.