A broad-band millimeter-wave optical modulator using a passively modelocked semiconductor laser with phase noise compensation

A new and simple technique to produce efficient optical modulation at millimeter-wave frequencies by compensating for the phase noise of a 0.85-μm passively modelocked semiconductor laser is presented. The passively modelocked laser is intensity modulated with the electrically mixed product of its phase noise and the millimeter-wave information signal. One of the resulting sidebands to the modelocked note is identical to the millimeter-wave frequency information because of the cancellation of the phase noise of the modelocked signal. A carrier-to-noise ratio (CNR) of 87 dBc/Hz at 41.9 GHz is demonstrated and it is shown that optical modulation at subcarrier frequencies up to 100 GHz and a CNR of 120 dBc/Hz is possible.