Balanced Photonic Microwave/Millimeter-Wave Mixer And Frequency Converter

A novel, high isolation photonic mixer/frequency converter architecture consisting of two cascaded balanced bridge Mach-Zehnder modulators is presented. When compared with a traditional cascaded single output Mach-Zehnder modulator architecture, the new device can effectively minimize the Ieakthrough of microwave input and local oscillator signals at the intermediate frequency output for high electrical isolation applications. Device operation principles, requirements on coupling angles, and phase bias offset at each modulator section are analyzed for performance optimization. High isolation photonic mixing has been obtained experimentally using a single chip lithium niobate device. The Ieakthrough of the input and focal oscillator signals was suppressed over 50 dB at the intermediate frequency output. This photonic mixer can be used in fiber-optic microwave links for low noise and low distortion millimeter-wave frequency conversion applications, particularly when the frequency response is limited by the millimeter-wave input ports. When operating in the upconversion mode, this photonic mixer can extend the output bandwidth to the sum of each modulator in cascading, as demonstrated in our experiment.