Photonics for mmW signal generation

Microwave signal generation based on photonics has been demonstrated to provide high-quality and software-defined RF signals with unprecedented frequency tuning in a very large RF spectrum including the millimeter wave (mmW) spectral range, for new generations of extremely adaptive and high-resolution radar systems. An important feature of the photonics-based RF generation is the high and constant performance on the whole interval of operation frequencies. In this way, photonics overcomes the limitations of electronic technologies, whose performance strongly degrade with the frequency increase. Moreover, photonics-based RF generation can be implemented on chip through photonic integrated circuits, making the solution competitive with today's RF oscillators, also in terms of size, weight and power consumption. Different photonic techniques can be adopted for mmW signal generation, i.e., based on injection locking of independent continuous wave lasers, multi-frequency lasers (e.g., mode locked laser, or opto-eletronic oscillators). This paper will detail on these techniques and it will show few important results demonstrating the large band of operation and the unprecedented performance of the photonics-based RF signal generators. Finally, an analysis of the requested integrated photonics technologies will be reported.