Low cost λ-tunable transmitter for indoor infrared wireless communication system

Optical wireless technology provides a future-proof solution for indoor communication due to its unparallel broadband features. Different from other applications, indoor communication networks are sensitive to the cost and complexity. Indoor beam-steered infrared wireless communication system (IWC) based on wavelength division device, e.g. arrayed waveguide grating is attractive due to its low cost. However, the traditional wavelength tunable transmitter is expensive. In this paper, we propose a low-cost wavelength tunable transmitter for an indoor beam-steered IWC system. The key device of such transmitter is a simple and low cost Fabry–Perot(F–P) cavity laser. Different from the external-modulator based solutions, the proposed transmitter provides gain rather than insertion loss, which further simplifies the system design and improves the system reliability. The optimal central offset in spectrum between the modulated signal and the wavelength division devices is also investigated to improve the system performance. A 4.5 Gb/s indoor IWC system incorporating 3.2-km single mode fiber and 1.1-m free space link is experimentally demonstrated.