Phase noise measurements are highly relevant in the development of electromagnetic wave sources. In the terahertz (100 GHz-10 THz) range, these are carried out with microwave base devices and waveguide-based frequency extenders. This has two disadvantages: 1) The waveguide bands are usually limited to a tunability of about 50% of the center frequency, 2) The mounting accuracy & the surface roughness make access to frequencies > 1.5 THz difficult.



The developed phase noise analyzer combines the tunability of photonic systems with the advantages of electronic measurement technology and low-noise photoconductors. Two laser systems provide a differential frequency in the terahertz range that can be set over several octaves, e.g. by means of two continuous wave lasers or two lines of a frequency comb. The photoconductor mixes the optical difference signal with the measurement signal and generates an easily measurable intermediate frequency signal