The present investigation aims at elucidating the photoluminescence (PL) behaviour of Tb3+ doped SiO2–M2O3 (M=Al, Ga)–LiF–CaF2 optical glasses. The absorption spectra of these glasses have revealed the absorption bands due to 7F6 → (5L8, 5G3, 5L9, 5G4, 5D2, 5G5), 5L10, (5G6, 5D3) and 5D4 transitions. The Tb3+ excitation bands are assigned to the electronic transitions of 4f8 → 4f75d1 and 4f8 → 4f8. The PL spectra with the excitation wavelength 378 nm recorded at room temperature of these glasses have exhibited the following emission transitions: 5D4 → 7FJ (J = 6, 5, 4, 3). An attempt has also been made to throw some light on the relationship between the structural modifications and luminescence efficiencies of both the two glasses. And found the fluorescence intensity of 543 nm emission in SGLCT is 46% higher than that in SALCT due to the different metal oxides viz., Ga2O3 and Al2O3.