This work reports the development of a high-gain and wideband photonic-assisted amplified radio over fibre (RoF) system based on the non-linear effect four-wave mixing (FWM). The microwave gain is defined as the difference between the electrical power photodetected using a FWM product and that from the conventional RoF system at the same optical power level. Numerical simulations and experimental results prove that microwave gain strongly depends on the system parameters, such as wavelength separation between pump sources, state of polarisation, radio frequency modulation frequency and DC bias voltage of optical modulator. Microwave amplification from 4 to 19 GHz, electrical signal-to-noise ratio higher than 51 dB and gain up to 26 dB at 17 GHz are demonstrated. Moreover, an optical-wireless network based on the photonic-assisted microwave application is proposed, with the purpose of illustrating its applicability.

The authors demonstrate the generation of soliton mode-locked pulses from an erbium-doped fibre ring laser incorporating molybdenum disulphide (MoS₂) saturable absorber (SA) with a net anomalous dispersion. The MoS₂ SA is prepared by mechanically exfoliating MoS₂ crystal and fixing the acquired MoS₂ flakes onto the end surface of a standard FC/PC fibre connector. A self-started mode-locked soliton pulse is generated by fine-tuning the rotation of the polarisation controller at the threshold pump power of 50 mW. Its solitonic behaviour is verified by the presence of Kelly sidebands in the output spectrum. The central wavelength, 3 dB bandwidth, pulsewidth, and repetition rate of the laser are 1598.94 nm, 5.4 nm, 0.83 ps, and 17.1 MHz, respectively. The maximum pulse energy is 74 nJ at pump power of 110 mW with the output power of 1.26 mW. The MoS₂ SA was constructed in a simple fabrication process and has a modulation depth of 11.3% to successfully produce the stable soliton mode-locked fibre laser.

A miniaturised red-emitting master-oscillator power-amplifier (MOPA) was developed. The MOPA emits a single longitudinal mode with a linewidth below 10 MHz and an optical output power of more than 300 mW at a wavelength of about 647 nm. The master-oscillator is a distributed-Bragg-reflector ridge-waveguide laser which provides the single mode with an output power of about 40 mW. The light is shaped by micro-lenses and guided through a miniaturised CdMnTe-Faraday isolator as well as a truncated tapered power amplifier; it is reshaped again afterwards to produce an almost circular, nearly diffraction-limited beam. The total length of the MOPA is below 50 mm, which fitted into a sealed butterfly package with a footprint of about 20 cm².

For improving energy efficiency and spectrum utilisation for elastic optical networks, an energy-efficient resources allocation algorithm based on spectrum-aware is put forward. In the proposed algorithm, a spectrum allocation algorithm based on spectrum integration is introduced first. The algorithm reduces spectrum fragmentation by taking the spectrum slots usage of neighbour links into account, which makes the subsequent arriving requests have more chance to be successfully transmitted on the paths with minimal power consumption. Moreover, a path re-routing mechanism, moving the requests which are not transmitted on their minimal power consumption paths to their minimal power consumption paths, is studied in the proposed algorithm. The simulation results show that the proposed algorithm not only improves energy efficiency, but also reduces the bandwidth blocking rate.

The authors propose a new high-resolution indoor positioning method based on visible light communication using two light emitting diode (LED) lightings and an image sensor of camera as a receiver. Through the proposed method, the authors can determine position of receiver using the real coordinate of two LED lightings and a captured image. In order to demonstrate the applicability of positioning method, they evaluated the positioning accuracy as changing receiver position. From the experimental results, positioning resolution of maximum 3 cm distance error is demonstrated under the square space with 96 cm height and maximum 6.5 cm distance error under the square space with 245 cm height.