Binary SnO−SiO2 and ternary SnO−SnF2−SiO2 glasses are investigated as potential alternative to lead containing glasses for the development of optical components using polarization light. Optical and thermal properties (including very small photoelastic constant, PEC) are reported herein. A minimum value of PEC (–0.008 × 10−12 Pa−1) is measured at a wavelength of 632.8 nm for the binary glass containing 43.6 mol% of SnO. The ternary glasses with fluorine of 8 − 9 mol% provide a very small PEC (–0.039 × 10−12 Pa−1) and blue-shifted optical absorption edge for 47.0 mol% of SnO+SnF2. The local structure of the silicate glass is investigated by micro-Raman and 119Sn, 29Si, and 19F nuclear magnetic resonance spectroscopies. It turns out that the zero PEC glass possesses a discrete silicate structure with meta- and pyro-silicate units. The relationship between the zero photoelastic property and the silicate structure is discussed.