Optical Amplification at 1.3 μm in a Praseodymium‐Doped Sulfide‐Glass Fiber

Praseodymium‐doped glasses were prepared in the Ga‐Na‐S (GNS) system and their optical properties were studied. A single‐mode fiber with an attenuation loss of 1.2 dB/m at a wavelength of 1.31 μm was fabricated using an extrusion method, and the amplification characteristics were measured in the bidirectional pumping configuration. We demonstrated a gain coefficient of 0.81 dB/mW at a wavelength of 1.34 μm, which is the highest we have ever reported, and achieved a net gain of 32 dB for a pump power of 90 mW. Highly efficient optical amplification at a wavelength of 1.3 μm was demonstrated in the praseodymium‐doped GNS fiber.