Homodyne detection

In optical interferometry, homodyne signifies that the reference radiation (i.e. the local oscillator) is derived from the same source as the signal before the modulating process.

The homodyne technique can suppress excessive noise and undesired quadrature components (90° out-of-phase), and provide stable access to information that may be encoded into the phase or polarity of images.

[5] However, challenges include reducing noise, increasing bandwidth and improving the integration of electronic and photonic components.

[6] Recently, these challenges have been overcome to demonstrate a free-space-coupled room temperature quantum sensor with large-scale integrated photonics and electronics.

An efficient receiver scheme for implementing QKD is balanced homodyne detection (BHD) using a positive–intrinsic–negative (PIN) diode.