Variable attenuation slope compensator (VASC) using silica-based planar lightwave circuit technology for active gain slope control in EDFAs

摘要

We propose a novel planar lightwave circuit (PLC)-based device called variable attenuation slope compensator (VASC) specifically designed for use inside the EDFA. The VASC is an electrically controllable optical attenuator whose attenuation slope (wavelength dependence of attenuation) is variable while the average attenuation within the operational wavelength range is unchanged. The VASC consists of two asymmetrical Mach-Zehnder interferometers The EDFAs employing the VASC have exhibited a dynamic range as large as 20dB and dynamic gain tilt as small as 0.6dB. The noise figure of the EDFA employing the VASC is about 4dB for an input level of 28dBm/ch, and it increases by about 9dB whiles the input level is increased by 20dB. This deterioration of the noise figure in the EDFAs employing the VASC is smaller than that observed in the EDFAs employing a variable optical attenuator.