Centimeter-scale Yb-free heavily Er-doped silica fiber laser.

Abstract

The laser behavior of a centimeter-scale Er3+/Al3+ codoped silica fiber with core numerical aperture and core diameter of 0.15 and 8μm, respectively, is reported. The core glass was prepared by the sol-gel method combined with high-temperature sintering; it contained Er3+ ion concentration as high as 1.32×1020 ions/cm3 and an Al/Er mole ratio of 10. The high doping homogeneity of Er3+ ions in the fiber core was confirmed by an electron probe microanalyzer element scanning, long Er3+: I13/24 emission lifetime of 11.4ms, and low refractive index fluctuation of fiber core (±1×10-4). The signal gain of fibers with 4.6cm, 10cm, and 16cm lengths was tested in the 1500-1620nm range. A gain of 7dB is achieved at 1560nm in a 16-cm-long EDF under 230mW pump power. Aimed for CO2 sensor application, the laser behavior of Er/Al codoped fiber was tested at 1572nm. A slope efficiency of 12% and an output power of 15mW were achieved in a 10-cm-long fiber under 166mW absorbed pump power. The newly developed silica fiber is promising for use in high-repetition-rate lasers.