EXPERIMENTAL-MEASUREMENT OF GAIN IN ERBIUM-DOPED FLUORIDE FIBER AMPLIFIER IN THE 850-NM SIGNAL BAND

In this letter, we report an efficient single-mode Er3+ doped fluoride fiber amplifier (EDFFA) in the 850 mm signal band. The Ti-Sapphire la ser was used to pump the EDFFA at 792 nm with an estimated absorbed pu mp power of 35 mW. The EDFFA used a 4.2 meter long NA = 0.39, lambda(c ) = 850 nm fluoride fiber as the active medium. A peak gain of 25 dB w as observed at 852 nm. The gain was measured for a 10 nm region betwee n 847.5 nm and 857.5 nm. The 3 dB gain bandwidth is less than 4 nm, Ho wever, the gain exceeded 20 dB over wavelength region of at least 7.5 nm. The gain and the gain bandwidth can be further increased by optimi zing the length of the active fiber.