Abstract

In this study, we designed and constructed a cost-effective electro-optic phase modulator (EOM) capable of generating a high modulation index and multiple sidebands without requiring an expensive, high-power RF amplifier by employing an RLC resonance condition, and evaluated its electrical and optical properties. At the resonance frequency of MHz, the electrical quality factor () of the phase modulator was measured to be 24. Through analysis using a Fabry-Pérot cavity, we demonstrated that a maximum phase modulation index of 6.8 could be achieved with a low input voltage amplitude of only 12 V. Furthermore, the constructed EOM was applied to modulation transfer spectroscopy (MTS) to systematically investigate the line shape variations of the MTS signal across a wide range of modulation indices. Our experimental results confirm that the slope of the frequency error signal is maximized near the modulation index of , independent of the pump beam intensity. The EOM construction and MTS signal optimization procedures presented in this study are expected to serve as a valuable educational and practical model for establishing low-cost, high-precision laser frequency stabilization systems in university-level modern physics and advanced optics laboratories with limited budgets.