In order to study the technology of optoacoustic communication between aerial platforms and underwater objects, a method of laser-generated sound with high repetition rate for underwater acoustic communication is presented in a thermal expansion mechanism. The narrow-band acoustic signal is calculated and validated by experimental results. n-frequency-shift keying (n-FSK) and n-multiple frequency-shift keying (n-MFSK) modulated signals are generated in this method. The in-water range, bandwidth and data rate are analyzed for different modulation methods based on existing laser technology. The performance of modulation method with high repetition rate is compared with existing method (modulation method with long pulse). The results show that this method can be used for communication of short range. Compared to n-FSK modulation, the performance of n-MFSK modulation is better on data rate but worse on in-water range. The in-water range of modulation method with high repetition rate is 1000 m, which is 40% further than that with long pulse for n-FSK modulation.