Fabrication of tellurite fiber devices using laser irradiation techniques for all-optical switching applications

An optical fiber grating coupler (FGC) is a grating-written fused fiber coupler in which a refractive index modulated grating is written in its tapered region. The FGC can be applied to an all-optical switch using a cross phase modulation in the grating. However, the silica based FGC switch requires a control light with high power for the switching, therefore it is difficult to apply the FGC switch for practical use. One of the solutions to reduce the control power is introducing high nonlinear fibers for FGC fabrication. In this paper, a recent progress in research on tellurite fiber device fabrications using laser irradiation techniques for all-optical switching applications is reviewed. Fused tellurite fiber couplers were fabricated using CO₂ laser irradiation, where optical coupling to the cross port was confirmed similar to fused silica fiber couplers. The extinction ratio at the cross port was ~6%. Tellurite fiber gratings were also fabricated using picosecond pulsed Nd:YAG laser irradiation. We could successfully fabricate a long period tellurite fiber grating with -12.6 dB attenuation peak at 1556 nm wavelength.