Bipolar tap photonic microwave notch filter using electroabsorption modulator-integrated distributed feedback laser diodes in a parallel configuration

We propose a bipolar tap photonic microwave notch filter scheme, which can be used to realize a fully integrated, semiconductor-based notch filter. The scheme is based on two electroabsorption modulator (EAM)-integrated distributed feedback laser diodes in a parallel configuration. We show that two filter taps with opposite polarities can be readily obtained by using the negative and positive slopes of the U-shaped electro-optic transfer functions of the EAMs under special design and operating conditions. An experiment was carried out to verify the working principle of the proposed scheme. Notch frequency tuning was also demonstrated by varying the laser wavelength spacing; the spacing was varied by changing the temperature. A frequency tuning range of ~1.8 GHz with a notch depth of ~40 dB was achieved.