L-Band Wavelength-Tunable Er³⁺-Doped Tellurite Fiber Lasers

The spectroscopic properties of Er³⁺-doped tellurite glasses were investigated and a 1 wt.% Er³⁺-doped tellurite fiber was fabricated for L-band lasers. Wavelength-tunable fiber lasers in a linear cavity based on Littrow configuration were developed and studied with different gain fiber lengths as well as output coupling ratios. Wavelength tunable range of 38 nm from 1589-1627 nm was achieved in the experiment with a 3-m Er³⁺-doped tellurite fiber laser pumped at 1570 nm. A maximum output power of 52.4 mW was obtained at 1614 nm. Compared to L-band Er³⁺-doped silica fiber lasers, the demonstrated Er³⁺-doped tellurite fiber lasers exhibit much higher optical signal-to-noise ratio (>30 dB), even at the longest operating wavelength of 1627 nm. Our simulation shows that the laser wavelength can be further extended to 1634 nm if the tellurite fiber loss is improved and the fiber cavity is optimized.