Development of a millimeter-long Travelling wave THz photomixer

International audienceTHz sources based on the optical-heterodyne (photo)mixing in an ultrafast photodetector are very promising since they operate at room temperature, are potentially compact, cost-efficient and, above all, are widely frequencytunable. However, their widespread use is currently hampered by available power levels in the µW range at THz frequencies. We present here a travelling wave structure, with millimeter level coherence length at THz frequencies opening the way to large active area (~4000 µm 2) photomixing devices capable of handling optical pump power beyond 1 W well beyond the capabilities of standard lumped-element devices using small active areas (<50 µm 2) needed to maintain a capacitance level (