Terahertz communication systems based on cascade Mach-Zehnder modulators

In order to effectively solve the problem of signal modulation in THz communication systems affecting the performance of communication systems, a Terahertz communication system based on cascade Mach-Zehnder modulators was introduced. Pseudo random nonreturn to zero(NRZ) code and radio frequency local oscillator signal with frequency 10GHz were mixed into cascade Mach-Zehnder modulators. By adjusting the bias voltage of both modulators, they were biased at the maximum transmission point and the minimum transmission point respectively. The generated optical signal was amplified by erbium-doped optical fiber amplifier(EDFA), THz signal was generated by four-wave mixing effect in high nonlinear fiber and mode was selected by phase shifted fiber Bragg grating(FBG). Error rate of the transmission of terahertz communication system can be obtained by the recovery ofthe base band data after photoelectric conversion. The results show that THz signal is generated and modulated in the communication system based on cascade Mach-Zehnder modulators. The system has the significance of applications of THz communication systems.