Tong Shao

100 Gb/s Multicarrier THz Wireless Transmission System With High Frequency Stability Based on A Gain-Switched Laser Comb Source

We propose and experimentally demonstrate a photonic multichannel terahertz (THz) wireless system with up to four optical subcarriers and total capacity as high as 100 Gb/s by employing an externally injected gain-switched laser comb source. Highly coherent multiple optical carriers with different spacing are produced using the gain switching technique. Single- and multichannel Terahertz (THz) wireless signals are generated using heterodyne mixing of modulated single or multiple carriers with one unmodulated optical tone spaced by about 200 GHz. The frequency stability and the phase noise of the gain switched comb laser are evaluated against free-running lasers. Wireless transmission is demonstrated for single and three optical subcarriers modulated with 8 or 10 GBd quadrature phase-shift keying (QPSK) (48 or 60 Gb/s, respectively) or for four optical subcarriers modulated with 12.5 GBd QPSK (100 Gb/s). The system performance was evaluated for single- and multicarrier wireless THz transmissions at around 200 GHz, with and without 40 km fiber transmission. The system is also modeled to study the effect of the cross talk between neighboring subcarriers for correlated and decorrelated data. This system reduces digital signal processing requirements due to the high-frequency stability of the gain-switched comb source, increases the overall transmission rate, and relaxes the optoelectronic bandwidth requirements.

Convergence of 60 GHz Radio Over Fiber and WDM-PON Using Parallel Phase Modulation With a Single Mach–Zehnder Modulator

We propose a converged radio over fiber and wavelength division multiplexing passive optical networks (WDM-PON) system compatible with wired and 60 GHz band wireless transmission by implementing two-band modulation with a single Mach-Zehnder modulator as parallel phase modulators. In this paper, broadband millimeter wave generation, which is compliant with the ECMA 387 standard, and 2.5 Gbps baseband transmission, which feeds up the requirement of fiber-to-the-home, are simultaneously realized after 25 km long optical fiber transmission. Furthermore, the interference between RF and baseband modulations is theoretically and experimentally investigated. The RF modulation impacts to the baseband signal for different RF modulation formats are deeply investigated.

25-Gb/s OFDM 60-GHz Radio Over Fiber System Based on a Gain Switched Laser

A 25-Gb/s OFDM 60-GHz radio over fiber (RoF) transmission system employing a gain switched DFB laser for millimeter-wave generation is demonstrated. Transmission performance below the 7% FEC limit is achieved over 50 km of fiber initially by employing precompensation. This precompensation overcomes phase noise caused by the optical phase decorrelation induced by chromatic dispersion on the two optical channels separated by 60 GHz. An externally injected gain switched laser is subsequently employed to eradicate the need for the precompensation, thus reducing phase noise and increasing the tolerance to the induced time delay between the optical tones. Transmission performance below the 7% limit is achieved over 25 km of fiber with 2-m wireless transmission in this case.

Phase Noise Investigation of Multicarrier Sub-THz Wireless Transmission System Based on an Injection-Locked Gain-Switched Laser

In this paper, we propose a multi-carrier THz wireless communication system using an injection-locked gain-switched laser as an optical comb source. The phase noise of the 192 GHz signal resulting from the beating of two optical comb lines is theoretically analyzed and experimentally examined. Moreover, a three channel, 10 Gbaud QPSK THz signal is generated, and transmission over 40 km standard single mode fiber (SSMF) is experimentally demonstrated.

60 GHz Radio Over Fiber System Based on Gain-Switched Laser

A radio over fiber (RoF) transmission system based on a gain-switched laser as an optical comb source is proposed and demonstrated. 12.5 Gb/s 16 quadrature amplitude modulation (16 QAM) signal generation and transmission over 25 km standard single-mode fiber is experimentally demonstrated using a 60 GHz carrier. The phase noise of the 60 GHz signal resulting from the beating of two partially phase uncorrelated optical tones is theoretically studied and experimentally investigated. Phase noise comparison with different linewidth comb sources is implemented in the proposed RoF system, and the performance of the various systems with different levels of phase noise is presented.

Chromatic Dispersion-Induced Optical Phase Decorrelation in a 60 GHz OFDM-RoF System

We propose and demonstrate a 25-Gb/s 16-quadrature amplitude modulation orthogonal frequency division multiplexing 60-GHz radio over fiber transmission system based on a gain-switched optical comb source. The impact of the phase noise caused by the optical phase decorrelation due to the chromatic dispersion is theoretically studied and experimentally investigated by employing a high linewidth comb source and transmitting over a 50-km standard single-mode fiber reel. A time delay precompensation is deployed based on the study of phase noise in order to reduce the phase noise impact, and thereby improve system performance.

100 km coherent Nyquist ultradense wavelength division multiplexed passive optical network using a tunable gain-switched comb source

We propose and experimentally demonstrate a long-reach Nyquist ultradense wavelength division multiplexed passive optical network using a tunable optical frequency comb source and a digital coherent receiver. Each of the six comb tones on a 12.5 GHz grid is modulated with a 12 Gbaud Nyquist polarization division multiplexed quadrature phase shift keyed signal which includes a 20% overhead for forward error correction. Unrepeated downlink transmission of 100 km is demonstrated at three different operating wavelengths across the C-band. A worst-case channel sensitivity of -35.3 dBm (59 photons/bit) is achieved at a bit error rate of 1.5 × 10-2, yielding a system loss budget of 35.7 dB.

DM-DD OFDM-RoF System With Adaptive Modulation Using a Gain-Switched Laser

We propose a 60-GHz orthogonal frequency division multiplexing (OFDM) radio over fiber system based on direct modulation-direct detection using an externally injected gain-switched DFB laser with adaptive modulation format. Power fading due to chromatic dispersion is mitigated by optimizing the bias current. Adaptive modulation for OFDM is used to improve the signal transmission performance. A 15.31-Gb/s 60-GHz OFDM signal generation and transmission over 25-km standard single-mode fiber is experimentally demonstrated.

Simultaneous transmission of gigabit wireline signal and ECMA 387 mmW over fiber using a single MZM in multi-band modulation

We propose a multi-band radio over fiber system compatible with wired and 60GHz band wireless transmission by implementing two-band modulation with a single Mach-Zehnder modulator. In this paper, broadband millimeter wave at 60 GHz band, which is compliant with the ECMA 387 standard, is generated by photodetection after 25 km long optical fiber transmission. Furthermore, baseband transmission, which feeds up the requirement of fiber-to-the-Home, has been realized simultaneously.

Injection Locked Wavelength De-Multiplexer for Optical Comb-Based Nyquist WDM System

We report a standalone four-output wavelength de-multiplexer (de-mux) using optical injection locking for simultaneous comb tone separation, amplification and power equalization. Optical amplification from -30 to 5 dBm per output wavelength is achieved. We illustrate the flexibility of the de-mux by separating two input combs with tone spacing of 12.5 and 6.25 GHz into 12.5-GHz spaced outputs. The system performance of the de-mux is demonstrated in a 100-km Nyquist ultra-dense wavelength division multiplexed network where the de-multiplexed comb tones are each encoded with 12-GBd Nyquist polarization division multiplexed quadrature phase shift keying. Experimental results indicate a worst case 1.5-dB receiver sensitivity penalty at 1.5e-2 bit error ratio for the transmitted comb tone channels when compared with the 400-kHz linewidth comb source seeding laser.