Heterodyne detection

1. What is homodyne and heterodyne detection?
2. Why use heterodyne detection?
3. What is the heterodyne principle?
4. What is the difference between heterodyne and homodyne?

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.

Why use heterodyne detection?

In practice, heterodyne detection can offer a much greater advantage in terms of sensitivity, because direct detection reaches the shot noise limit only for rather high signal powers, whereas with heterodyne detection the standard quantum limit can be reached for much lower signal powers.

What is the heterodyne principle?

The principle that multiple frequencies applied to a nonlinear device produce new frequencies that are sums and differences of the applied frequencies and their harmonics.

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.