High-Capacity Directly Modulated Optical Transmitter for 2-μm Spectral Region

• Published in: Journal of lightwave technology 2015-04, Vol.33 (7), p.1373-1379
• Main Authors: Zhixin Liu, Yong Chen, Zhihong Li, Kelly, Brian, Phelan, Richard, O'Carroll, John, Bradley, Tom, Wooler, John P., Wheeler, Natalie V., Heidt, Alexander M., Richter, Thomas, Schubert, Colja, Becker, Martin, Poletti, Francesco, Petrovich, Marco N., Alam, Shaif-ul, Richardson, David J., Slavik, Radan
• Format: Article
• Language: English
• Subjects: Amplifiers; Bandwidth; Digital signal processing; Fibers; Modulation; Optical fiber amplifiers; Optical fiber communication; Optical modulation; Optical transmitters; Semiconductor lasers; Spectra; Transmitters; Wave propagation
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2015.2397700

The 2-μm wave band is emerging as a potential new window for optical telecommunications with several distinct advantages over the traditional 1.55 μm region. First of all, the hollow-core photonic band gap fiber (HC-PBGF) is an emerging transmission fiber candidate with ultra-low nonlinearity and lowest latency (0.3% slower than light propagating in vacuum) that has its minimum loss within the 2-μm wavelength band. Second, the thulium-doped fiber amplifier that operates in this spectral region provides significantly more bandwidth than the erbium-doped fiber amplifier. In this paper, we demonstrate a single-channel 2-μm transmitter capable of delivering >52 Gbit/s data signals, which is twice the capacity previously demonstrated. To achieve this, we employ discrete multitone modulation via direct current modulation of a Fabry-Perot semiconductor laser. The 4.4-GHz modulation bandwidth of the laser is enhanced by optical injection locking, providing up to 11 GHz modulation bandwidth. Transmission over 500-m and 3.8-km samples of HC-PBGF is demonstrated.