We demonstrate a novel method to greatly enhance the narrowband millimeter-wave (MMW) power generation by use of a near-ballistic uni-traveling-carrier photodiode-based photonic transmitter (PT) excited by shaped optical pulses. The spectrum of the best tailored optical pulses is centered at 1545 nm and spread among 16 main frequency components (channels), each with a spectral width of 15.5 GHz and a spacing of 93 GHz. Compared with quasi-sinusoidal optical modulation, we achieve an enhancement in the spectral power density by similar to 25 times. The power-enhanced narrowband MMW signal can be tuned over similar to 80 GHz (60-142 GHz). In addition, we observe significant enhancement of MMW peak power with an increase of the reverse bias voltage.