We report the amplification of 250 GHz pulses as short as 260 ps without observation of
pulse broadening using a photonic-band-gap circuit gyrotron traveling-wave-amplifier. The
gyrotron amplifier operates with a device gain of 38 dB and an instantaneous bandwidth of 8
GHz. The operational bandwidth of the amplifier can be tuned over 16 GHz by adjusting the
operating voltage of the electron beam and the magnetic field. The amplifier uses a 30 cm
long photonic-band-gap interaction circuit to confine the desired TE 03-like operating mode …