We change feedback phases of two coupled chaotic lasers to achieve bidirectional simultaneous transmission of signals between the two lasers. The partial transparent mirror between the lasers can induce delay and the chaotic dynamics. Numerical simulation of laser rate equation considering delay proves that the two lasers can achieve high-quality synchronization. The encoding and decoding process starts with the change of the feedback phases of the two lasers induced by signals. And then the difference in the optical power of the chaotic carrier in the two lasers is detected and compared with the difference with the local signal, finally, the digital messages sent by sender are recovered. Based on the eye diagram of recovered signal, it reveals that this system has a high transmission quality. In this scheme, the eavesdroppers cannot know the local signal even if he can get the difference of the transmitted signals. So the security of transmission performance of this system can be guaranteed as the eavesdroppers are unable to demodulate the sender's information.