Homodyne and heterodyne detection

1. What is homodyne and heterodyne detection?
2. What is the difference between heterodyne and homodyne?
3. How does homodyne detection work?
4. What is heterodyne technique?

What is homodyne and heterodyne detection?

Homodyne detection is a powerful yet simple method for measuring the quadrature components of electric field. Using heterodyne detection, we can down-convert a high-frequency signal to lower frequency.

What is the difference between heterodyne and homodyne?

Homodyne systems can use a common laser source, but everything else (interferometer, detection, and signal processing) must be duplicated per axis. Heterodyne systems, conversely, can use a common laser source, optical reference, and signal processing electronics for multiple axes.

How does homodyne detection work?

A homodyne detector directly measures the phase dependent quadrature of the quantum state's electric field. Therefore homodyne detection enables continuous variable quantum key distribution schemes with classical and non-classical states [1-4]. It also allows phase estimations at the Heisenberg limit [5, 6].

What is heterodyne technique?

Heterodyning is used to shift signals from one frequency range into another, and is also involved in the processes of modulation and demodulation. The two input frequencies are combined in a nonlinear signal-processing device such as a vacuum tube, transistor, or diode, usually called a mixer.