A vector system that uses a single laser source and a dual-polarized Mach-Zehnder modulator (MZM) to generate two channels of optical radio frequency signals at different frequencies is experimentally studied. Using the optical subcarrier multiplexing technology, two channels of quadrature phase shift keying (QPSK) signals can be carried by two optical subcarriers with different frequencies based on a modulator and an optical carrier. The polarization multiplexing technology is used to overcome crosstalk of optical signals with different frequencies, and the signals can be successfully transmitted over an 80-km-long single-mode fiber (SMF). In the experiment, 15- and 30-GHz QPSK signals are modulated using a dual-polarized MZM based on a single sideband modulation format. After the 80-km SMF transmission, the 15-GHz QPSK signal transmission performance is better than that of the 30-GHz signal. When the input power of a photodetector (PD) is more than -10.2 dBm, the bit error rate (BER) of a system after demodulation is less than 3.8×10 -3. The system has the advantages of simple structure, low complexity, and few electrical and optical devices, which effectively reduce cost and play a considerable role in the development of future access networks.