Q-factor enhancement in micro hemispherical resonators by laser welding

The quality factor (Q-factor) is a pivotal metric for affecting the precision and performance of micro hemispherical resonator gyroscopes. Currently, the primary impediment to enhancing the Q-factor is anchor loss, which is significantly affected by interlayer between the micro hemispherical resonator and substrate. Therefore, this paper proposes an innovative interlayer-free bonding technique based on femtosecond laser welding for integrating resonators with substrates. Firstly, an anchor loss simulation model was established to analyze the influence mechanisms of eccentric mass and interlayers on Q-factor. This analysis reveals that interlayer-free bonding significantly mitigates energy dissipation caused by eccentric mass. Secondly, a material temperature evolution model was constructed based on the interaction mechanism between femtosecond laser and fused silica, which reveals the influence of laser parameters on weld pool morphology. Subsequently, a laser welding platform was established and optimal process parameters were obtained via single-factor experiments. Finally, the experimental results show that the micro hemispherical resonator bonded by femtosecond laser welding achieves a maximum Q-factor of 11.77 million, representing a 37 % improvement compared to the conventional conductive adhesive bonding method. Notably, a decay time of 639.04 s was achieved, marking the longest decay time reported to date for micro hemispherical resonators. This research results validate the effectiveness of femtosecond laser welding in enhancing Q-factor, holding significant implications for manufacturing high-performance micro hemispherical resonator gyroscopes.