Heterodyne phase-shift-amplified interferometry with improved shot-noise-limited sensitivity and immunity to RIN

Phase-shift-amplified interferometry (PAI) is demonstrated using a heterodyne detection scheme. We demonstrate a sensitivity amplification factor of 35, giving $7.9 \cdot {10^{ - 4}}$7.9⋅10^-4 rad, or 40 pm displacement, resolution. This was achieved due to the improved immunity of PAI to the total relative intensity noise (RIN) of the system. In addition, we predict a factor of $\sqrt 2 $2 fundamental improvement to shot-noise-limited phase-shift sensitivity as compared to a regular heterodyne Mach-Zehnder interferometer.