Phosphosilicate fiber opens door to 1300-nm Raman amplifiers with improved efficiency
At two Russian institutes, researchers have been developing an efficient 1300-nm Raman fiber amplifier to work with installed terrestrial fiber infrastructure, which operates predominantly at 1300 nm. The work from the Fiber Optics Research Center at the General Physics Institute (Moscow) and the Institute of Chemistry of High Purity Substances (N. Novgorod) advances the potential of Raman fiber amplifiers in both analog and digital telecommunications. Raman fiber amplifiers have been hampered by low efficiency and the need for a compact, low-cost pum¥source; the cascaded Raman fiber lasers that currently pum¥these amplifiers are complex and expensive. To improve the design, the researchers developed a phosphosilicate fiber-based Raman laser as a pum¥source to work with a 4-km-long, low-loss, high-index-of-refraction germanosilicate fiber amplifier. Experimental results show a Raman gain of 40 dB at a 1240-nm pum¥power of less than 700 mW.