Recent Results From the EU POF-PLUS Project: Multi-Gigabit Transmission Over 1 mm Core Diameter Plastic Optical Fibers

Recent activity to achieve multi-gigabit transmission over 1 mm core diameter graded-index and step-index plastic optical fibers for distances up to 50 meters is reported in this paper. By employing a simple intensity-modulated direct-detection system with pulse amplitude or digital multi-tone modulation techniques, low-cost transceivers and easy to install large-core POFs, it is demonstrated that multi-gigabit transmission up to 10 Gbit/s over 1-mm core diameter POF infrastructure is feasible. The results presented in this paper were obtained in the EU FP7 POF-PLUS project, which focused on applications in different scenarios, such as in next-generation in-building residential networks and in datacom applications

Analogue RF over fibre links for future radar systems

The distribution of analogue RF signals within a high performance radar system is challenging due to the limited space available and the high levels of performance required. This work investigates the gain, linearity and noise performance that can be achieved by an externally modulated direct detection link designed for operation up to 20 GHz using commercially available components. The aim was to assess the suitability of such links for use in future radar systems. Good correlation has been shown between modelled and measured results demonstrating that the performance should satisfy the linearity requirements for many radar applications

Radio frequency over fiber technology for SKA-low receiver

The signal reception chain is an essential element for achieving the square kilometer array-low (SKA-low) system requirements in terms of high sensitivity and dynamic range. The balance between gain, linearity, and low power consumption, as well as the cost, are fundamental parameters that influence the selection of the most suitable technology for SKA-low. Further factors, such as low self-generated radio frequency (RF) interference, high reliability, robustness under extreme environment, and last but not least, the distance between the antennas and the acquisition systems, have impacts on the selection for both architecture and receiver system design. The selected technology for the SKA-low RF signal transportation is RF-over-fiber systems, where the preamplified RF signal picked up by the antennas is carried via analogue modulation over optical fiber. The rationales behind the selection are reported, along with descriptions on the development of the receiver prototypes. The prototypes were deployed and installed on the demonstrator arrays at the selected SKA-low site in Western Australian. Particular attention has been put on the thermal characterization of the receiver system under the actual operating temperature on site, especially when both transmitting part and the optical medium are subjected to external ambient temperature variations. Performance issues encountered in the demonstrator arrays are also discussed along with some proposals for future activities

Exceeding octave tunable Terahertz waves with zepto-second level timing noise

Spectral purity of any millimeter wave (mmW) source is of the utmost interest in low-noise applications. Optical synthesis via photomixing is an attractive source for such mmWs, which usually involves expensive spectrally pure lasers with narrow linewidths approaching monochromaticity due to their inherent fabrication costs or specifications. Here, we report an alternative option for enhancing the spectral purity of inexpensive semiconductor diode lasers via a self-injection locking technique through corresponding Stokes waves from a fiber Brillouin cavity exhibiting greatly improved phase noise levels and large wavelength tunability of ~1.8 nm. We implement a system with two self-injected diode lasers on a common Brillouin cavity aimed at difference frequency generation in the mmW and THz region. We generate tunable sub-mmW (0.3 and 0.5 THz) waves by beating the self-injected two wavelength Stokes light on a uni-travelling carrier photodiode and characterize the noise performance. The sub-mmW features miniscule timing noise levels in the zepto-second (zs.Hz^-0.5) scale outperforming the state of the art dissipative Kerr soliton based micro-resonator setups while offering broader frequency tunability. These results suggest a viable inexpensive alternative for mmW sources aimed at low-noise applications featuring lab-scale footprints and rack-mounted portability while paving the way for chip-scale photonic integration.Comment: 31 page

36 Gb/s Narrowband photoreceiver for mmwave analog radio-over-fiber

Migrating toward higher frequencies and densification of the communication cells are two key enablers for increased wireless data rates. To make these trends economically viable, centralized architectures based on radio-over-fiber (RoF) are explored. This article describes the design of a photoreceiver that can be applied at the remote radio head in a 28 GHz analog RoF link. The devised photoreceiver comprises a Ge-on-Si photodetector and co-designed GaAs low noise amplifier offering 24 dB gain, corresponding to 224 V/W external conversion gain, over a 3-dB bandwidth between 23.5 and 31.5 GHz. The associated noise figure is 2.1 dB and an output referred third order intercept point up to 26.5 dBm can be obtained with a power consumption of 303 mW. Two possible applications are demonstrated in this article. First, the photoreceiver is tested in a 5G New Radio environment resulting in rms-EVM values below 2.46/3.47% for 100/400-MBaud 16-QAM transmission over the 24.25-29.5 GHz band. Secondly, very high data rates can also be supported, demonstrated by a 36 Gb/s link with an rms-EVM of 5.2%