Two-frequency laser source stabilized on a single fiber interferometer for low phase noise and frequency-stable millimeter-wave generation

The constant evolution of wireless communication systems, where increasingly greater capacity of data volume management is required, has led many researchers to explore the millimeter-wave terahertz bands (0.1-10 THz). The generation of data signals at such frequencies often rely on optical techniques, among which the heterodyning of two lasers offers among other advantages a wide frequency tunability of the high frequency carrier. The frequency stability of the carrier is among the key parameters for the performances of a communication system. We report here on a scheme where two narrow-linewidth laser sources are stabilized on a single fiber interferometer, following a double optical frequency locked loop (OFLL) architecture. We show that with this simple setup involving only low-frequency electronics, the frequency stability of the heterodyne signal is improved from a few tens of MHz to below 100 kHz, while it can be tuned from a few tens of MHz up to a few THz.