Photonic-crystal fiber achieves 10 Gbit/s transmission in the visible

Increasing demand for broadband services is encouraging researchers to improve the performance of photonic-crystal (PC) fibers, which offer the potential for communication systems with a bandwidth of 260 THz or more, relying on a large spectral bandwidth. Researchers at NTT (Ibaraki, Japan) have moved closer to practical implementation of such fibers by demonstrating successful 10 Gbit/s transmission over a 1 km length of PC fiber using a 780 nm single-mode grating-stabilized laser diode, and 1 Gbit/s transmission using a 783 nm Fabry-Perot laser diode.

The 125 µm outer-diameter, 11 µm core-diameter PC fiber contained 60 air holes with a hole-diameter to hole-pitch ratio of 0.5. For the 783 nm transmission over a 1 km length of fiber, optical loss was 4.9 dB/km, chromatic dispersion was -107 ps/nm-km, and a bit-error rate (BER) of 10-9 was observed with a received power level of -30 dBm. With the use of the grating-stabilized 780 nm source, the BER improved to 10-11, realizing the first penalty-free 10 Gbit/s visible transmission for a PC fiber. Contact Kenji Kurokawa at kurokawa@ansl.ntt.co.jp.