Polarization-independent all-optical clock division using a semiconductor-optical-amplifier/grating-filter switch

We propose and experimentally demonstrate, for the first time to our knowledge, polarization-independent all-optical clock division (CD) of an optical pulse train at 2.88 GHz. This is achieved using a semiconductor-optical amplifier (SOA)/grating-filter switch, where the SOA acts as a spectral shifter by a self-phase modulation (SPM) and the grating filter acts as a spectral shutter. The proposed scheme is very insensitive to the polarization of input pulses and requires very low switching energy (/spl sim/102 fJ). After the all-optical CD operation, we have obtained the output pulse train at 1.44 GHz, which is half the input repetition rate, with high extinction ratio (>20 dB).