Broadband Extended Dynamic Range Analog Signal Transmission Through Switched Dual Photonic Link Architecture

The design and experimental performance of a 40-GHz microwave photonic link scheme developed for broadband analog signal transmission that exhibits an increased input dynamic range compared with conventional microwave photonic links is presented. The scheme achieves an extension in the input power operating range by switching between two photonic links designed to operate at different input power levels, where the optical fiber provides the required delay for the switching operation. Although the extension in the dynamic range is noninstantaneous, the scheme has application in high-sensitivity receiver systems in a pulsed signal environment due to its feedforward gain control mechanism. This paper presents, through a realistic simulation study, the device parameter values required for optimized performance of a wideband (2-40 GHz) link with the noise figure, sensitivity, and dynamic range performance of each link and the composite link. A total "synthetic" dynamic range >;100 dB with a minimum detectable signal of -110 dBm at a 100-kHz noise bandwidth can be achieved for the 2-40-GHz frequency range operation. The simulation results compare well with experimental results obtained with a practical implementation of the dual link architecture. The design and operational details of the switching circuitry required are also presented.