Phase-Modulated Analog Photonic Link With a High-Power High-Linearity Photodiode

Abstract

We investigate phase-modulated analog photonic link performance using interferometric detection with a Mach–Zehnder interferometer (MZI) under different bias conditions and a high-power high-linearity modified unitraveling carrier (MUTC) photodiode (PD). Expressions for radio frequency (RF) small signal gain and the optimal MZI bias point for RF gain are derived, and noise figure (NF) and third-order spurious free dynamic range (SFDR3 ) are analyzed. Using a 28- μ m-diameter MUTC single PD with 23 dBm RF output power under 155-mA saturation current at 10 GHz, we measured a record-high link gain of 25 dB, 18 dB NF, and ${\text{114}}\;{\text{dB}} \cdot {\rm{H}}{{\rm{z}}^{{\text{2/3}}}}$ SFDR3 at 130 mA photocurrent with an optimally biased MZI. By using a 24- μ m-diameter balanced MUTC PD pair with 21 dBm RF output power at 108 mA at 10 GHz, we obtained a 16 dB link gain, 16 dB NF, and ${\text{118}}\;{\text{dB}} \cdot {\rm{H}}{{\rm{z}}^{{\text{2/3}}}}$ DR3 at 100 mA total dc photocurrent when the MZI was biased at quadrature. The RF gain at both MZI bias points is in good agreement with our calculations.