Optimal Biasing of a Self-Homodyne Optically Coherent RF Receiver

Abstract

We present a technique that achieves the most efficient use of the linear dynamic range of available photodiodes without sacrificing the linearity of the radio-frequency (RF) digital receiver and photonic link based on optical phase modulation and coherent in-phase quadrature $(I/Q)$ demodulation. We demonstrate, with a relative intensity noise (RIN)-limited optical system, that under these optimal bias conditions our 1-GHz coherent receiver achieves a link spurious-free dynamic range (SFDR), gain, and noise figure of 126.8 $\hbox{dB-Hz}^{2/3}$, 8 dB, and 18.6 dB, respectively, and show the capability, with a shot-noise-limited optical source, to achieve an SFDR of 135.3 $\hbox{dB-Hz}^{2/3}$ and a noise figure of 6 dB.

Keywords

• Coherent transmission
• microwave photonics
• $I/Q$ demodulation%22%2C%22default_operator%22%3A%22AND%22%7D%7D%7D"> <formula formulatype="inline"><tex Notation="TeX">$I/Q$</tex></formula> demodulation
• phase modulation