The doped colour center Nd: YAG crystal can be used as an active medium or a passive modulator. The passive Q-switching pulse width is equal to or greater than 7 ns, the active and passive mode-locking pulse width is equal to or greater than 270 ps. When the pulse repetition rate is within 1-10 kHz, the pulse duration is equal to or greater than 200 ns. Nanosecond or subnanosecond active and passive mode-looking pulse durations are obtained and the frequency-doubling average output power is about 300 mW.