Efficient Mode Conversion from a Standard Single-Mode Fiber to a Subwavelength-Diameter Microfiber

Efficient mode conversion is crucial for hybrid photonic systems. We present efficient light transition from a standard single-mode fiber (SMF) to a subwavelength-diameter microfiber via a relatively short tapered fiber. Numerical simulations were performed to design the tapered morphology with high transmittance (approximately 86%) for the fundamental modes. The designed tapered fiber was successfully fabricated on the top of a cleaved SMF tip by the direct laser writing (DLW) method. For the 1550 nm wavelength, the transmittance from the standard SMF to the subwavelength-diameter microfiber was determined to be 77%, accompanied by a change in the effective mode area from 38 mu m2 to 0.47 mu m2 within a very short length of 150 mu m. Our result demonstrated the versatility of the DLW technique for boosting the mode conversion efficiency of fiber-to-chip devices, enabling various applications in the future.

Automated summary

Efficient mode conversion from standard single-mode fiber to subwavelength-diameter microfiber was achieved using a tapered fiber, resulting in a significant change in mode area within a short length. This method is important for the development of hybrid photonic systems.