Reduction of Fresnel Back-Reflection at Splice Interface Between Hollow Core PCF and Single-Mode Fiber

Optical feedback from the Fresnel reflection at the air-silica interface of a splice between a hollow core photonic crystal fiber (HC-PCF) and a conventional fiber can cause laser instability or damage. The reported solution consists of the preparation of angle cleaved fibers, spliced together using a filament fusion splicer. A reduction of 44 dB of the return loss is observed. The method will considerably reduce potential damage such as fiber fusion in case of a fiber laser. The method is also demonstrated to decrease the Fabry-Perot effect in setups such as saturable absorption when the spliced HC-PCF is used as a gas cell device.