Frequency conversion ; Harmonic generation, including higher-order harmonic generation ; Glasses, quartz ; High-field and nonlinear effects ; In the development of high bit-rate capacity in telecom systems, fiber technology and/or integrated glass waveguides provide a means to implement low cost active optical devices with low insertion losses and fiber compatibility. Presently glass-based devices are limited in efficiency and it is of the utmost importance to increase the non linear optical response. In this context the present investigation compares the induced second-order optical nonlinearity generated after electro-thermal poling process in a series of borophosphate glasses of molar compositions 0.3[(0.9 - x) Ca(PO3)2–x Zn(PO3)2–0.1 CaB4O7]–0.3 Nb2O5 (x = 0–0.4). The mechanisms involved are tentatively explored.