Dr Liu's research interests are focused on i) Design, fabrication and characterisation of advanced photonic devices, in particular, the Asymmetric Fabry-Perot modulator (AFPM) which can be used as both a light intensity modulator and a photodetector in a single device. ii) Radio-over-fibre systems and techniques. Novel and low-cost transmission techniques for wireless multiple-input-multiple-output (MIMO) signal over fibre. iii) Microwave Photonics. High-speed photonic sampling techniques. iiii) Real-time indoor location systems using active RFID tags, optical fibres and associated signal processing techniques.