Phase noise of an electro-optical phase modulator based electro-optical comb

Photonic millimeter wave and terahertz frequency generation and detection benefit from a large tunability of several octaves as opposed to electronic frequency generation and multiplication. However, reaching multiple 100GHz continuous tuning range while simultaneously featuring a linewidth in the Hz range and low phase noise is still very challenging. We present an electro-optical comb driving a photomixer with potential usability as an extension module based on side-band generation by an electro-optical phase modulator. This enables a Hz-level linewidth from microwaves to terahertz frequencies. We discuss the working principle of the mentioned electro-optical comb, characterize the phase noise of the optical subsystem up to frequencies of 40GHz where electronic phase noise analyzers are available and draw conclusions on the phase noise at higher frequencies in the THz domain.