Method of power recycling in CoAxial Mach-Zehnder interferometers for low noise measurements

We present the first experimental study of a new type of power recycling microwave interferometer designed for low noise measurements. This system enhances sensitivity to phase fluctuations in a device under test, independent of input power levels. The single sideband thermal white phase noise floor of the system has been lowered by 8 dB (reaching −185 dBc/Hz at 1 kHz offset frequency) at relatively low power levels (13 dBm).