Arrayed-waveguide grating lasers and their applications to tuning-free wavelength routing

The authors propose two kinds of tunable arrayed-waveguide grating (AWG) lasers. One is an AWG ring laser using an AWG multiplexer and an erbium-doped fibre amplifier (EDFA). The other is an AWG Fabry-Perot laser constructed using an AWG multiplexer with the minimum number of inputs/outputs and laser diode (LD) amplifiers; fewer than the desired number of wavelengths. These fabricated 1.55 μm tunable AWG lasers are shown to oscillate successfully at 16 and 32 wavelengths with a 0.8 nm wavelength spacing. As the useful application of the tunable AWG laser source for dense wavelength division multiplexing (WDM) networks, a new lightwave transrouter (LTR) is constructed using the AWG multiplexer formed of an appropriate pair of a fibre ring laser and a wavelength router. The LTR can successfully route a lightwave signal to a desired wavelength-addressed channel. The fabricated 1.55 μm 15-channel tunable LTR is routed automatically to the corresponding channel. The unique configuration is particularly attractive because of the principle tuning-free mechanism. Additionally, a reflective modulator is introduced into a sourceless optical network unit (ONU) for WDM passive optical networks (PONs) and then its fine-signal response is obtained