A solid-core tellurite glass fiber with $1.8\mathrm{dB}/\mathrm{m}$ loss at $1.55\mathrm{\mu m}$ was made by using the built-in casting preform fabrication method and rod-in-tube fiber drawing technique. Pumping a $10\mathrm{cm}$ fiber piece with picosecond pulses of 3– $5\times {10}^{12}\mathrm{W}/{\mathrm{cm}}^2$ , 0.1% of the fundamental power limited by the coherence length of 0.3– $5\mathrm{\mu m}$ was converted into visible third-harmonic power tunable over a broad near-IR wavelength ranging from 1500 to $1680\mathrm{nm}$ . Frequency conversion from the mid-IR to near-IR was found to be even more efficient due to the longer coherence lengths of 12– $20\mathrm{\mu m}$ in the wavelength range of 2200– $2500\mathrm{nm}$ .