Millimeter-wave bands are attracting attention because of the availability of wideband for high-speed transmission.
However, due to the limitation of the performance of electric signal processing, it is rather difficult to modulate and
demodulate millimeter-wave signals with high-speed baseband modulation. In this paper, we describe optical signal
processing for high-speed modulation of millimeter-wave, based on high-speed and precise lightwave control. In optical
fiber communication systems, various types of modulation formats, such as quadrature-amplitude-modulation, are
reported to achieve high-speed transmission. Optical two-tone signals can be converted into millimeter-wave signals by
using high-speed photodetectors. This technique can be used for distribution of stable reference signals in large-scale
antenna arrays for radio astronomy. By using the millimeter-wave signal generation technique and the optical advanced
modulation formats, we can achieve high-speed modulation of millimeter-waves, where the carrier frequency and bit rate
can be over 90GHz and 40Gb/s, respectively.