In the proposed scheme, only three Mach–Zehnder modulators (MZMs) in cascaded mode are employed to generate a frequency 12-tupling millimeter wave (mm-wave) signal. In order to eventually get the frequency 12-tupling mm-wave signal, it is necessary to generate ±6th order harmonics. Therefore, the next work is to generate pure ±6th order optical sidebands to obtain a high-quality frequency 12-tupling signal. First of all, by adjusting the MZM bias voltage at peak point to suppress odd order sidebands; then, by controlling the phase differences to cancel even order sidebands except for the (6n)th order; lastly, by setting the modulation index to eliminate the 0th order optical carrier. Based on the above, the pure ±6th order optical harmonics are obtained. Moreover, the feasibility of the scheme has been demonstrated through a simulation. The optical sideband suppression ratio (OSSR) and radio frequency spurious suppression ratio (RFSSR) of the generated signal are 59.45 dB and 44.44 dB, respectively. In the end, the non-ideal factors that will affect the signal quality are also analyzed.

In this paper, a filterless 32-tupling millimeter wave generation scheme based on eight MZMs is proposed. The system has an upper and lower parallel two-branch structure. The upper branch consists of two subsystems Sub-A and Sub-B in cascade, each subsystem contains four MZMs, and the MZMs are all operating at maximum transfer point (MATP). Sub-A mainly generates ±8th order optical sideband signal as the incident light signal of Sub-B. After modulation of Sub−B, the output signal is mainly ±16th order optical sideband signal containing the central optical carrier component. The optical attenuator (OATT) and optical phase shifter (OPS) of the lower branch are used to regulate the phase and amplitude of the optical carrier. The upper and lower branches are coupled, and the central optical carrier component is superimposed and cancelled so only the ±16th order optical sideband signal is retained. Finally, the 32-tupling frequency millimeter is generated by the photodiode (PD) receiver after photoelectric detection which receives and generates a 32-tupling frequency millimeter wave signal. The simulation results show that the 160 GHz millimeter wave signal can be obtained by driving the MZM with a 5 GHz RF signal, and the optical sideband suppression ratio (OSSR) and the RF sideband suppression ratio (RFSSR) are 52.6 dB and 44.75 dB, respectively. Theoretical analysis and simulation experiments are carried out for the proposed scheme which proves the feasibility of the scheme.

A new photonic scheme is proposed for the generation of a frequency 16-tupling millimeter wave (mm-wave) signal, based on four cascaded polarization modulators (PolMs). Firstly, through the precise control of these four PolMs, odd harmonics can be effectively suppressed sequentially. Next, combined with the modulation index of the PolMs, only the pure ± 8th-order optical harmonics are retained and enter the photodetector to beat the frequency. After multiple rounds of detailed, mathematical formula derivation and computer simulation, the accuracy and advantages of the proposed solution can be demonstrated. As a result, a 160 GHz mm-wave signal is obtained, which is produced from a 10 GHz radio frequency (RF) signal. By properly setting the modulation index and the angle of three phase differences, the optical suppression ratio (OSSR) and the radio frequency suppression ratio (RFSSR) of the acquired signal are 64.21 dB and 60.99 dB, respectively. Further, the impact of the variables on the OSSR and the RFSSR are analyzed and discussed.

A quantum noise stream cipher (QNSC) is a physical layer encryption technology based on quantum noise. Bit error rate loopback measurement (BER-LM) is a method to measure the BER of a loopback channel and extract channel characteristics. Then, channel characteristics can be extracted, and consensus keys can be obtained through negotiation. In previous studies, encryption and key distribution were implemented in independent channels. In this paper, we propose a scheme that combines these two technologies in a single fiber channel to achieve encrypted transmission and key distribution. We verified a 20 Gbps QPSK coherent optical transmission system with a PSK/QNSC scheme. The results show that by reasonably setting the negotiation bit position, the consensus key could be obtained through negotiation, and the requirements of transmission performance could be met. When the negotiation bit position was set to seven, the Q-factor of the system was nine, which met the error-free condition of the 7% forward error correction (FEC) limit.

This paper proposes a novel key distribution method based on the masking effect of fiber channel noise in a power transmission system. The two physical layer signal processing technologies used in this solution are frame synchronization and resampling. The random data sent and received is digitally processed by these two techniques. An experimental platform is built, and the key performance is assessed by analyzing the measured bit error rate (BER) dynamic curve, setting different decision thresholds and the amplitude of the state basis. Experimental results show that the key distribution rate can reach 10 kbit/s with a key consistency rate of 98%. This is of great significance to the development of safe optical communication technology in power transmission systems. In the power communication system, a large number of optical fiber communication devices are used. The key distribution method proposed in this paper can effectively improve the security of optical fiber communication, which is of great significance.