Efficient narrow-band direct modulation of semiconductor injection lasers at millimeter wave frequencies of 100 GHz and beyond

Abstract

It has been demonstrated both theoretically and experimentally that it is possible to mode lock semiconductor lasers at millimeter wave frequencies approaching and beyond 100 GHz. The mode-locked output usually takes the form of sinusoidal modulation, and can be regarded for practical purposes as a highly efficient means of directly modulating an optical carrier in a narrow band at millimeter wave frequencies. In active mode locking, the external signal efficiently creates the optical modulation, while in passive mode locking a small external signal imposes its information on the optical carrier by injection locking the passive mode-locked output. Experimentally, we have demonstrated passive mode locking at 70 GHz using a tandem contact GaAs laser.