Cascaded Mach-Zehnder Modulators Research Articles

Polarization division multiplexed photonic radio-frequency channelizer using an optical comb

A polarization division multiplexed photonic radio-frequency (RF) channelizer based on an optical comb is proposed and numerically investigated. A flat optical comb with nine lines is generated using two cascaded Mach–Zehnder modulators. The input broadband signal is simultaneously multicast by the optical comb and its frequency-shifted duplicate. These two combs are polarization multiplexed, spectrally sliced by a Fabry–Pérot etalon (FPE), polarization de multiplexed and then channelized by wavelength division multiplexers (WDMs). The key advantage of the proposed approach is that it releases the trade-off between the measurement range and accuracy of a conventional optical comb based channelizer by a factor of 2. The impact of the polarization misalignment, the capability of monitoring multi-frequency RF signals with different powers and the reconfigurability of the system are also evaluated.

A cost-effective WDM-PON architecture simultaneously supporting wired, wireless and optical VPN services

It is believed that next-generation passive optical networks (PONs) are required to provide flexible and various services to users in a cost-effective way. To address this issue, for the first time, this paper proposes and demonstrates a novel wavelength-division-multiplexed PON (WDM-PON) architecture to simultaneously support three types of services: 1) wireless access traffic, 2) optical virtual passive network (VPN) communications, and 3) conventional wired services. In the optical line terminal (OLT), we use two cascaded Mach–Zehnder modulators (MZMs) on each wavelength channel to generate an optical carrier, and produce the wireless and the downstream traffic using the orthogonal modulation technique. In each optical network unit (ONU), the obtained optical carrier is modulated by a single MZM to provide the VPN and upstream communications. Consequently, the light sources in the ONUs are saved and the system cost is reduced. The feasibility of our proposal is experimentally and numerically verified.

Analysis of an optical mm-wave generation scheme with frequency octupling using two cascaded Mach–Zehnder modulators

We propose a novel method to generate optical mm-wave signals with frequency octupling using two cascaded Mach–Zehnder modulators (MZMs). First, the scheme is investigated both theoretically and by simulation, and results show that an 80 GHz mm-wave is generated by a 10 GHz RF oscillator. Then, an analytical expression is developed to describe the performance of the scheme. The influences caused by non-ideal factors are discussed in detail, and undesired sidebands suppression ratios are plotted and analyzed. At last a RoF system using the mm-wave generation scheme is demonstrated and its BER curves indicate that the performance of the system is still good even if the parameters deviate from the ideal values to a certain degree.

Simplified optical millimeter-wave generation configuration by frequency quadrupling using two cascaded Mach–Zehnder modulators

We propose what we believe to be a novel method to generate optical millimeter-wave signals with frequency quadrupling using two cascaded Mach-Zehnder modulators (MZMs). Both theoretical analysis and experimental demonstration are presented. By symmetrically biasing the MZMs, without any optical filters or electrical devices, a high-quality millimeter wave at 40 GHz with an optical harmonic distortion suppression ratio of more than 25 dB is obtained. Furthermore, it is also proved to be valid that the proposed scheme is insensitive to the MZM bias drift, which demonstrates a relatively higher stability.

An optical (Q)PSK-RF-signal transmitter based on two cascaded Mach–Zehnder modulators

This paper proposes an optical transmitter to generate phase-shift-keying (PSK) radio frequency (RF)-signal, using two cascaded single-drive Mach–Zehnder modulators (SDMZMs). With input of a continuous-wave (CW) light, an electrical non-return-to-zero (NRZ) data, and an RF-local oscillator (RF-LO) signal at a frequency of ω l , the transmitter can simultaneously produce three PSK signals and two CW tones on both sides in spectrum, by employing nonlinear modulation technique. With the help of optical filters, the desired signals can be selected to mix at a photodetector (PD) to obtain a PSK-RF-signal with the carrier frequency of ω l , 3 ω l , or 5 ω l . Our scheme can be easily extended to generate quadrature PSK-RF-signal. The feasibility of our proposal is experimentally and numerically verified.