Stable lightwave frequency synthesis over 1-THz span using Fabry-Perot cavity containing polarization-rotation elements and actively controlled tunable bandpass filter

We realized a lightwave synthesized frequency sweeper which has a >1-THz sweep span and operates stably. We employed an actively controlled tunable bandpass filter together with a Fabry-Perot cavity, which consisted of a Faraday rotator mirror and a polarization rotation mirror. We confirmed that the frequency information of an input pulse was preserved after 1000 round-trips in the cavity and that signal pulses could circulate stably for 12 h.