Ziran Zhang

Fiber-Wireless-Fiber Link for 100-Gb/s PDM-QPSK Signal Transmission at W-Band

We propose and experimentally demonstrate a W-band seamlessly-integrated fiber-wireless-fiber system enabled by photonic millimeter-wave generation and demodulation techniques, in which up to 109.6-Gb/s polarization division multiplexing quadrature phase shift keying signal can be first transmitted over 80-km single-mode fiber-28 (SMF-28), then delivered over a 2-m 2 × 2 multiple-input multiple-output wireless link at 95 GHz and finally transmitted over another 80-km SMF-28 with a bit-error ratio less than the third-generation forward-error-correction limitation of 2 × 102. The proposed fiber-wireless-fiber integration system has throughput comparable with that of fiber-optic communication and is suited to emergency back-up communications.

W-Band 8QAM Vector Signal Generation by MZM-Based Photonic Frequency Octupling

We propose a novel scheme for photonic multiamplitude quadrature-amplitude-modulation (QAM) vector signal generation at microwave/millimeter-wave bands enabled by Mach-Zehnder modulator (MZM)-based adaptive photonic frequency multiplication. In order to attain an electrical millimeter-wave vector signal displaying multiamplitude QAM modulation, such as 8QAM, after square-law photodiode detection, the driving radio-frequency (RF) signal, carrying multiamplitude QAM transmitter data, should be both amplitude- and phase-precoded before used to drive the MZM. We experimentally demonstrate 8QAM vector signal generation at W-band adopting photonic frequency octupling (×8) enabled by our proposed scheme. The MZM is driven by a 12-GHz precoded RF signal carrying 1-GBaud 8QAM transmitter data. The generated 1-GBaud 8QAM vector signal at W-band is air transmitted over 2-m distance. To the best of our knowledge, it is the first time to realize the generation and reception of multiamplitude QAM vector signal by one external modulator at W-band.

QAM Vector Signal Generation by Optical Carrier Suppression and Precoding Techniques

We numerically and experimentally investigate and compare photonic constant- and multi-amplitude quadrature-amplitude-modulation (QAM) vector signal generation at radio frequency (RF) bands enabled by a Mach-Zehnder modulator (MZM)-based optical carrier suppression (OCS) modulation. In order to attain an electrical vector RF signal displaying multi-amplitude QAM modulation, such as 8 QAM and 16 QAM, after square-law photodiode detection, the driving RF signal carrying multiamplitude QAM transmitter data, should be both amplitude- and phase-precoded before used to drive the MZM. However, for constant-amplitude QAM modulation, such as quadrature-phase-shift-keying (QPSK), only phase precoding is needed. We experimentally demonstrate 1-GBd vector signal generation at 12 GHz enabled by an MZM-based OSC modulation, adopting QPSK, 8 QAM, and 16 QAM modulation, respectively. We also experimentally compare the bit error rate performance of the three different vector signals, and the QPSK case is the best, while the 16 QAM case is the worst.

High-Frequency Photonic Vector Signal Generation Employing a Single Phase Modulator

In this paper, we propose a novel and simple method to generate millimeter-wave vector signals using only one phase modulator (PM) and phase-precoding technique, in which the precoded microwave vector signal is used for the drive of the single PM. We experimentally demonstrate that this concept of the generation of quadrature-phase-shift-keying-modulated vector signal can be employed in our radio-over-fiber (RoF) system architecture based on our proposed scheme. By this scheme, we simplify the configuration and reduce the cost of the RoF system.

OFDM Vector Signal Generation Based on Optical Carrier Suppression

We propose a novel method to generate photonic quadrature-phase-shift-keying (QPSK) orthogonal frequency division multiplexing (OFDM) vector signal using only one Mach-Zehnder modulator, in which the OFDM signal is phase precoded and amplitude precoded according to the square-law characteristic of the photodetector. We theoretically analyze and experimentally demonstrate that this concept of the generation of the QPSK OFDM vector signal can be employed in our system architecture based on our proposed scheme. The results show that the bit-error ratios of the transmission system are less than the forward-error-correction threshold of 3.8 × 10-3. By this scheme, we simplify the configuration and reduce the cost of the OFDM transmission system.

W-band OFDM photonic vector signal generation employing a single Mach-Zehnder modulator and precoding.

We present a simple radio-over-fiber (RoF) link architecture for millimeter-wave orthogonal frequency division multiplexing (OFDM) transmission using only one Mach-Zehnder modulator (MZM) and precoding technique. In the transmission system, the amplitudes and the phase of the driving radio-frequency (RF) OFDM signal on each sub-carrier are precoded, to ensure that the OFDM signal after photodetector (PD) can be restored to original OFDM signal. The experimental results show that the bit-error ratios (BERs) of the transmission system are less than the forward-error-correction (FEC) threshold of 3.8 × 10(-3), which demonstrates that the generation of OFDM vector signal based on our proposed scheme can be employed in our system architecture.

20-Gb/s PDM-QPSK signal delivery over 1.7-km wireless distance at W-band

We experimentally demonstrate 1.7-km wireless delivery of 20-Gb/s@85.5-GHz PDM-QPSK signal with a BER less than 3.8×10-3, which, to the best of our knowledge, is the longest wireless transmission distance at W-band up to now.

Experimental Investigation on Fiber-Wireless MIMO System With Different LO at W Band

We experimentally demonstrate an optical-wireless transmission system at W band, which can support long-distance wireless transmission and tolerate some frequency difference of the local oscillators (LOs) at the receiver. The generation of millimeter-wave signal is based on the photonic technique by heterodyne mixing of an optical polarization division multiplexing quadrature phase shift keying (PDM-QPSK) signal and an optical LO signal. After 20-km fiber transmission, tens of gigabit-per-second millimeter-wave signals are delivered over multiple-input-multiple-output (MIMO) wireless links by different polarization antennas. Then, analog downconversion is performed before the received signal is demodulated by coherent detection and advanced digital signal processing. Using this system, we experimentally demonstrate the transmission of 18.7-, 29.9-, and 37.4-Gb/s PDM-QPSK wireless signals at W band over 80-, 40-, and 20-m wireless links, respectively, with bit error rate less than the forward error correction threshold of 3.8 × 10-3. In addition, we investigate the effect of different frequency LOs on the MIMO system performance, finding that the system can tolerate about 1.25-GHz frequency difference for a 10-Gbaud signal. The proposed system can be suitable for the building-to-building broadband connection, in-building hybrid fiber-wireless access networks, and some scenarios that bridge natural obstacles and difficult-to-access terrain.

Demonstration of 60 Gb/s W-Band Optical mm-wave Signal Full-Duplex Transmission Over Fiber-Wireless-Fiber Network

In this letter, we propose and experimentally demonstrate a W-band (75-110 GHz) full-duplex transmission fiber-wireless-fiber system with the rate up to 60 Gb/s for the first time. Both the uplink and downlink in our proposed system consist of two spans of 80 km single-mode fiber-28 (SMF-28) and a 1-m wireless link. We experimentally demonstrate that our proposed system can simultaneously transmit a 60 Gb/s upstream quadrature-phase-shift-keying (QPSK) signal carried by 99 GHz carrier frequency over the uplink and a 60 Gb/s downstream QPSK signal carried by 101 GHz carrier frequency over the downlink. Both millimeter-wave generation and demodulation are enabled by photonic techniques. Wireless crosstalk that occurs between the uplink and the downlink is effectively avoided because the pair of antennas adopted in the uplink is polarization orthogonal to that adopted in the downlink. With the optical signal-to-noise ratio (OSNR) of 20 dB, the bit error ratios (BERs) for 60 Gb/s signal transmission are less than the third-generation forward-error-correction (FEC) limitation of 2 × 10-2.

Demonstration of 120 Gbit/s full-duplex signal transmission over fiber-wireless-fiber network at W-band

We demonstrate full-duplex transmission of 120-Gb/s PDM-QPSK signal over simplified fiber-wireless-fiber network at W-band for the first time. The network is realized by photonic generation and demodulation techniques with a BER less than 2×10-2.