CW injection seeding of a modelocked semiconductor laser

The injection locking technique is extended to control the output of a modelocked semiconductor laser with an external CW signal. With this injection seeding technique, over 8 mW of average power in 30-psec pulses with side cluster suppression of over 20 dB was obtained from an actively modelocked AlGaAs semiconductor laser. This average output power compares favorably with the 12-mW CW output power of the extended resonator. The frequency spectrum of the laser is determined by the background noise level as set by the spontaneous emission. Injection seeding overrides the noise and concentrates over 99 percent of the available energy in a single nearly transform-limited pulse.