A Filter-Free Photonic Microwave Single Sideband Mixer

Single-sideband mixer plays an important role in microwave and millimeter wave systems. In this letter, a novel filter-free photonic microwave single-sideband mixer based on carrier-suppressed single sideband (CS-SSB) modulation is demonstrated by using a dual-parallel Mach-Zehnder modulator (DPMZM). In the method, when the optical CS-SSB-modulated signal consists of a
${+}1$
st-order sideband generated by the intermediate frequency (IF) signal and a
${-}1$
st-order sideband generated by the local oscillator (LO) signal, an up-converted upper sideband (USB) RF signal can be obtained after photodetection. On the other hand, when the CS-SSB-modulated optical signal contains two
${+}1$
st-order (or
${-}1$
st-order) sidebands, an up-converted lower sideband (LSB) RF signal is generated at the output of the mixer. An experiment is carried out. Both the undesired sideband and the LO leakages are suppressed by more than 30 dB when the single-sideband mixer is operating in either USB or LSB mode without using an optical or electrical filter.