Photonic microwave harmonic down-converter based on stabilized period-one nonlinear dynamics of semiconductor lasers.

Photonic microwave harmonic down-conversion is demonstrated using an optically injected semiconductor laser operating at period-one (P1) nonlinear dynamics. In this method, the P1 oscillation is stabilized through low-frequency local oscillator signal modulation, thus generating high-order harmonics in the optical domain. Meanwhile, a radio-frequency (RF) signal is received by an intensity modulator. After the subsequent optical heterodyning, photonic microwave harmonic down-conversion can be realized. In the proof-of-concept experiment, the 4th, 6th, 9th, and 12th harmonic down-conversions are demonstrated; i.e., an RF signal with a frequency of 39 GHz is down-converted to frequency-tunable intermediate frequency (IF) signals within 2 GHz. The resultant IF signal mainly holds the microwave linewidth and phase noise comparable to those of the original high-frequency one.