Super-broadband near-infrared photoluminescence from thulium, bismuth, and thulium-bismuth doped sodium germanium gallate glasses and waveguides

Substantial progress in the production of hydroxyl-free silica fibers (dry optical fibers) have led to transmission wavelength region from 1.2 to 1.7 µm, thus it is attractive to explore superbroadband luminescence sources for broadband near-infrared (NIR) optical amplifiers, and tunable lasers operating in this entire low loss wavelength region [1]. Rare earth ions (e.g., erbium, thulium, holmium, and praseodymium) doped material systems play a significant role in the optical amplification and laser sources at separate C-, L-, S-, E-, and O-band wavelength regions [2]. Novel gallate/tellurite oxide glasses have been investigated to further improve the bandwidth and the quantum efficiency of specific rare earth luminescence [3,4]. Also, wavelength/frequency resources located in the first window (1.45–1.65 µm) have been explored and obtained from Tm-Er codoped configuration due to their NIR emission characteristic in this region [5]. However, up to now it remains a challenge to obtain super-broadband luminescence/amplification covering the entire extended transmission window from rare earth ions doped materials due to their restricted gain bandwidth characteristics.