Optical wavelenght converter with a dynamic Brillouin filter and an electronic compensating device

We present an experimental and theoretical study of a highly robust wavelength converter at 10 Gbit/s that is based on a narrow bandstop Brillouin filter. The wavelength conversion takes place in a semiconductor optical amplifier in a cross-gain-phase process, which operates in a weak-modulation mode. The signal then undergoes a carrier reduction by a spectrally narrow bandstop filter. Since we use a Brillouin grating as the narrow filter, the signal is distorted owing to the filter's finite spectral width (∼20 MHz). To overcome this problem, we use a relatively slow electronic mechanism to effectively narrow the filter's spectral width and to improve its signal-to-noise ratio. We elaborate on this electronic mechanism by developing the underlying theory and showing how it is implemented in practice. Although we focus on an application for wavelength conversion, this technology can be implemented in many other cases in which an effective narrowing of a bandstop filter is required.