Nd3+-doped fluoroaluminate glasses for a 1.3 mu m amplifier

A Nd3+-doped 1.3 mu m fiber amplifier has the potential to be an efficient, high-gain device. A major problem to overcome is the long wavelength of th e gain spectrum. In the majority of Nd3+-doped glasses the gain is shifted out of the second telecom window as a result of long-wavelength emission an d signal excited-state absorption (ESA). In this article we present new flu oroaluminate glasses developed as hosts for the 1.3 mu m Nd3+-doped fiber a mplifier. Nd3+ emission peaks below 1320 nm were demonstrated in bulk glass es. Gain in the 1310-1320 nm region was measured in unclad fibers, with evi dence of significantly reduced ESA. Another serious problem in amplifier de sign lies in overcoming the competing amplified spontaneous emission (ASE) at 1050 nm. We discuss ASE filtering using in-fiber Bragg gratings and pres ent results supporting its feasibility. The article also examines thermal a nd viscous properties of matched core and cladding glasses in relation to p reform and fiber fabrication. (C) 2000 American Institute of Physics. [S002 1-8979(00)08605-9].