Wideband multimode fiber with an optimized core size and fluorine-doped cladding for high-speed SWDM and CWDM transmission.

We propose a novel multimode fiber (MMF) with a 30 μm-core and fluorine-doped cladding for both high-speed short wavelength division multiplexing (SWDM) and coarse wavelength division multiplexing (CWDM) transmission. By optimizing the core size, the mode field diameter (MFD) mismatch between the proposed fiber and both the standard single-mode fiber (SMF) and MMF is minimized, which enables the quasi-single mode operation in the CWDM window and a compromised coupling loss with standard MMFs and SMFs. By adopting a fluorine-doped silica cladding, the bandwidth dependence on wavelength of the proposed fiber is minimized, which indicates that the modal bandwidth performance at the longer wavelength can be effectively improved without compromising modal bandwidth at 850 nm. The error-free 100 Gb/s (4×25.78 Gb/s) multimode transmission over 250 meter-long fiber is achieved using a commercially available VCSEL-based SWDM transceiver. The applicable distance can be extended to 300 meters when a biterror rate just below the forward error correction (FEC) threshold of 5×10  is acceptable. Besides, the 100 Gb/s error-free single-mode transmission over 10 km-long fiber was also demonstrated with a commercially available directly modulatedlaser (DML)-based CWDM transceiver. The results imply that the proposed MMF may be useful for large-scale data center applications.