Photonic Vector Modulator Research Articles

Automatic bias control suitable for a microwave photonic vector modulator

Automatic bias control suitable for a microwave photonic vector modulator

Microwave photonic signal processing techniques and radio-over-fiber transmission demonstration

Radio-over-fiber (RoF) utilizing microwave photonic signal processing techniques is a powerful solution for the future super-broadband wireless access. In this paper, we review our recent works on photonic processing techniques of microwave signals for RoF applications and experimental demonstration of RoF transmissions. Our works specifically focus on impulse-response ultra-wideband (IR-UWB) pulse generation for UWB-over-fiber systems, photonic vector modulation, novel analog modulation format, multi-service RoF system design and experimental demonstrations.

Photonic DPASK/QAM signal generation at microwave/millimeter-wave band based on an electro-optic phase modulator

We have proposed and experimentally demonstrated two novel photonic architectures to generate differential-phase amplitude-shift keying and circular quadrature amplitude modulation signals at microwave/millimeter-wave band based on an electro-optic phase modulator. In our proposed schemes, the electronic driven circuits were greatly simplified by employing the photonic vector modulation technique.

Photonic Generation of M-QAM/M-ASK Signals at Microwave/Millimeter-Wave Band Using Dual-Drive Mach–Zehnder Modulators With Unequal Amplitudes

Based on photonic vector modulation (PVM) techniques, several novel schemes are proposed to generate 4-ary amplitude shift keying (4-ASK), 16-ary quadrature amplitude modulation (16-QAM), and 16-ary amplitude shift keying (16-ASK) signals at microwave/millimeter-wave (mm-wave) band. First, a 4-ASK signal generation architecture based on dual-drive Mach-Zehnder modulators (MZMs) with unequal amplitudes is proposed and experimentally demonstrated. Then by combining two 4-ASK signal generation schemes in parallel, PVM architectures for 16-QAM and 16-ASK signal generation are proposed employing three MZMs, a tunable optical delay line (ODL), and an optical attenuator. The detailed theoretical analysis, experiment, and simulation certification of these structures are carried out. Compared with the conventional methods, the electronic driven circuits in the proposed schemes are simplified by employing PVM techniques.

Performance Analysis of Photonic Vector Modulation Techniques for Multi-Gb/s Wireless Links

Broadband access networks evolution towards 10-Gb/s user connectivity will foster the evolution of the photonic and wireless technologies needed to implement multi-Gb/s wireless links. In particular, provision of data rates in excess of 1 Gb/s using wireless technologies is limited by currently available electrical technologies due to the required bandwidths and frequencies of operation in the millimeter-wave (mm-wave) band. Microwave photonic techniques and technologies have shown a clear potential to overcome these limitations. In this paper, the detailed study of a photonic vector modulator (PVM) architecture and its performance limitations are presented. The PVM architecture is based on direct baseband modulation and dispersion induced quadrature condition. The limitation of this architecture is the presence of a local oscillator (LO) component in the generated mm-wave spectrum which limits the system dynamic range. To overcome this limitation, a third continuous-wave (CW) laser is used to remove the unwanted LO component by properly adjusting its wavelength and emitted power. After presenting the theoretical model, the LO suppression feature is demonstrated experimentally by generating a 1.25-Gb/s QPSK 41-GHz modulated carrier. The two options (with and without LO carrier) are compared in terms of relevant performance parameters.

A Novel Direct Detection Microwave Photonic Vector Modulation Scheme for Radio-Over-Fiber System

This letter demonstrates the feasibility of a novel direct detection microwave photonic vector modulation scheme for the radio-over-fiber (RoF) system. Unlike the traditional double-sideband with optical carrier suppression modulation scheme, which can carry only the on-off keying data format, the proposed scheme encodes the electrical vector signal on either the upper sideband (USB) or the lower sideband (LSB) only and a pure optical subcarrier on the other sideband. Therefore, phase and amplitude information will be preserved after direct detection. A frequency doubling scheme is employed to reduce the cost of RoF systems. Additionally, the relative intensity between USB and LSB can be easily tuned by adjusting the individual power of electrical driving signals to optimize the performance of the optical radio-frequency signals. A proof-of-concept experiment is conducted by using a 1.25 Gb/s BPSK signal at a carrier frequency of 20 GHz. After transmission over 50-km single-mode fiber, the receiver sensitivity penalty is less than 0.5 dB.

Generation of pure electrical quadrature amplitude modulation with photonic vector modulator

A photonic vector modulator architecture for generating pure quadrature amplitude modulation (QAM) signals is presented. An electrical quadrature-modulated signal at microwave-millimeter-wave frequencies is generated from its corresponding baseband in-phase (I) and quadrature (Q) components. In the proposed scheme, no electrical devices apart from the electrical tone oscillator are needed in the generation process. In addition, the purity of the generated signal is increased, and the hardware requirements are reduced when compared with previously proposed architectures so a highly compact low-cost architecture can be implemented. A pure 1.25 Gbit/s 4-QAM signal has been experimentally generated at a 42 GHz carrier frequency.

Generation of Multi-Gigabit-per-Second MQAM/MPSK-Modulated Millimeter-Wave Carriers Employing Photonic Vector Modulator Techniques

In this paper, two photonic vector modulator (PVM) architectures are presented, and their use in generating multi-gigabit-per-second M-ary quadrature amplitude modulation/M-ary phase shift keying modulated RF carriers in the millimeter-wave frequency regime is experimentally demonstrated. First, a highly scalable photonic quadrature amplitude modulation (QAM) architecture based on vector summation and dispersive delay lines, which directly generate multilevel signals from parallel in-phase and quadrature components, is proposed and experimentally demonstrated by generating up to 3-Gb/s quadrature phase shift keying (QPSK), four-level amplitude shift keying, and eight-level QAM at 39-GHz-modulated carriers. The possibility of also detecting the baseband components is shown, which allows the simultaneous feeding of baseband/RF signals over the same infrastructure. This architecture is limited to a certain length of fiber, as the quadrature condition is obtained for a certain aggregated dispersion. To overcome this limitation, a second PVM architecture is proposed, which is based on the use of two Mach-Zehnder modulators in parallel and an optical delay line to obtain the quadrature condition. The generation of a 2-Gb/s QPSK signal is experimentally demonstrated, including a 1-km standard single-mode-fiber transmission.

Direct photonic generation of electrical vector modulations at microwave/millimeter-wave frequencies

In this letter, a novel quadrature photonic vector modulator architecture is proposed. An electrical quadrature-modulated signal at microwave/millimeter-wave frequencies is generated from its corresponding base-band in-phase (I) and quadrature (Q) components. In the proposed scheme, no electrical devices apart from the electrical tone oscillator are needed in the generation process and, therefore, high data rates at high electrical frequencies can be obtained. In addition, the hardware requirements are reduced when compared to previously proposed architectures so a highly compact low-cost architecture can be implemented. Experimental results demonstrate the feasibility of the architecture.

Microwave photonic vector modulator for high-speed wireless digital communications

The authors present the design, realization, and experimental results of a microwave/photonic circuit suitable for high-speed direct digital modulation of microwave signals. The modulator employs a combination of microwave, photonic, and digital techniques to produce a discrete phase and amplitude (i.e., vector) modulated carrier signal. The proof-of-concept demonstration presented in this paper was performed using a carrier frequency of 1 GHz and supports BPSK, QPSK, and 16-QAM. The authors also discuss ways to modify the modulator to simultaneously achieve data rates on the order of several hundreds of Mbs and wideband frequency hopping.