A Phase-Modulation I/Q-Demodulation Microwave-to-Digital Photonic Link

Abstract

We present theory and experiments for a microwave-to-digital photonic link capitalizing on the linearity of optical phase modulation and coherent optical I/Q demodulation to achieve unprecedented gain and dynamic range performance. We demonstrate, with an optical amplifier noise limited system, direct demodulation spur-free dynamic range (SFDR), gain, and noise figure of 126.8 dB-Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> (86.8 dB in 1 MHz noise bandwidth), 8 dB, and 18.6 dB, respectively for inputs up to 1 GHz. Additionally we demonstrate complimentary all-photonic downconversion allowing the extension of input operating bandwidth to a modulator limited 40 GHz. Demonstrated microwave to intermediate frequency conversion loss ranges from <; 4 dB @ 4 GHz to <; 13 dB @ 40 GHz. Linear all-photonic downconversion and demodulation is demonstrated at 3 and 10 GHz with optical amplifier noise limited SFDR better than 107 dB-Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> (67 dB in 1 MHz noise bandwidth). System design issues are discussed including critical parametric sensitivities and optical-electrical-digital sub-system dynamic range matching and technology capability for downconverting microwave-to-digital SFDR performance in excess of 125 dB-Hz <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2/3</sup> (85 dB in 1 MHz) with current technology.