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Abstract: This study experimentally demonstrates the performance of optical frequency quadrupling generation and base-band signal up-conversion techniques based on the cascaded single-electrode Mach–Zehnder modulator (SEMZM) using different signal modulation schemes. The optical signals in microwave band with double-sideband suppressed-carrier (DSB-SC) modulated format exhibit that the receiver sensitivity and the spectral efficiency are maximized and the power penalty over long-distance delivery is minimized. A simple configuration and low-frequency bandwidth requirement for both electrical and optical components in the proposed schemes also are demonstrated. [Copyright &y& Elsevier]

Abstract: A general model of analog microwave photonic links employing cascaded amplitude and phase external modulation is theoretically derived. Chromatic dispersion is also included in the model showing a different dispersion induced attenuation response in comparison to pure phase or amplitude modulation. Thus, hybrid modulation can be used to increase the bandwidth of radio over fiber links without the need of single-sideband modulation or dispersion compensation. Experimental results agreeing with the derived theory are also provided. [Copyright &y& Elsevier]

The fiber optic communication is the one where the wired and the wireless communication systems are integrated to have high bandwidth, low cost, and high data rate with high user density. The RoF technology brings about high-performance network and the guaranteed quality of service for the increased demand for multimedia services. The RoF faces problems like distortion and chromatic dispersion in the RoF link, reducing the quality of the signal at receiver. To enhance the quality of the signal at the receiver side, several techniques have been reported. Those techniques concentrated on the RoF link and the modulation schemes used in the technology. This article reviews the complete RoF technology, which includes the challenges that limit the RoF network along with its compensation scheme and the RoF in the PON services with security. Along with that, the comparative study on the problems faced by the RoF and its mitigation schemes, such as linearization techniques and compensation for chromatic dispersion, are discussed. The linearization schemes will analyze the different pre-distortion circuits used to linearize the transmitting signal such that the signal received by the mobile unit is free of distortion. When these problems are reduced, the RoF with PON has faced another major problem of insecure transmission. Hence the performance of the existing encryption schemes is compared. [ABSTRACT FROM AUTHOR]

Abstract: A multi-tone radio over fiber (RoF) system design for three RF signals has been investigated for different modulation techniques like direct and external modulation with EDFA and SOA amplification techniques. Frequency response has been studied including the effects of third order intermodulation terms. Frequency separation between the modulating tones has been varied to study its impact on received carrier power. The performance in terms of electrical RF power of three receiving channels at different frequency separations using different amplification techniques have been measured and compared. An improvement in the received RF power and IM suppression has been observed by using an external modulation based system with EDFA amplifier. [Copyright &y& Elsevier]

• The generated signal repetition rate is quadruple that of the driving frequency, which means high-speed triangular-shaped signals can be obtained by using low-speed RF driving signal. • The scheme is immune to dispersion elements and filters, which make the repetition rate tunability more effective. • The modulation indexes required in our scheme are low and not fixed, which are preferred in practical. An improved photonic generation of full-duty-cycle triangular waveforms based on external modulation and orthogonal polarization control is proposed. The external modulation configuration consists a dual-parallel Mach–Zehnder modulator (DP-MZM) and a remodulation structure. After external modulation, four main sidebands with uniform frequency interval existed in the optical spectrum. To obtain the target triangular waveform, the modulation indices of modulators need to be carefully adjusted to guarantee the amplitude ration of inner-sideband and outer- sideband is desired 9.5 dB. Subsequently, polarization control is utilized to eliminate the coherent interference of different sidebands. Based on our proposal, triangular waveforms at 10 GHz, 20 GHz, 30 GHz and 40 GHz are achieved. The proposal might be attractive since that the generated signal repetition rate is frequency-tunable and frequency-quadrupled. [ABSTRACT FROM AUTHOR]