RF modules 1-6G microwave optical fiber transmission module(RF over fiber link) is composed of transmitter module and receiver module, and the working principle as shown below. The transmitter uses a high linear linear direct-mode DFB laser (DML) and integrates automatic power control (APC) and automatic temperature control (ATC) circuit, so that the laser can have efficient and stable output.The receiver integrates a high linear PIN detection and low noise broadband amplifiers. Microwave signal modulates laser to produce intensity modulated optical signal directly to achieve electro-optical conversion, after single-mode fiber transmission, the receiver completes photoelectric conversion, and then the signal is amplified and output by the amplifier.