We propose and demonstrate a flexible and high-speed impulse radio ultrawideband (IR-UWB) over fiber system using various modulation schemes. Two kinds of fully Federal Communication Commission (FCC) compliant UWB pulses are produced, which is based on the incoherent summation of multiple monocycle pulses with inverse polarities, proper time delays, and different weights. Theoretically, their spectral power efficiency can achieve 33.9% and 47.4%, respectively, which is much higher than that of the conventional monocycle and doublet pulses. A good agreement between the theoretical and experimental results for the generation of designed UWB pulses is also observed. Moreover, electrically reconfigurable multiple modulation formats such as on-off keying (OOK) modulation, binary phase shift keying (BPSK) modulation, pulse shape modulation (PSM), and pulse position modulation (PPM) are implemented experimentally. Furthermore, the UWB signals with OOK, BPSK, and PPM are transmitted over a combined wired (single-mode fiber) and wireless link. The transmission performance of the newly generated UWB pulses is then evaluated by electrical spectra, eye diagrams, and bit-error-rate measurements. For all the modulation formats, a forward-error-correction (FEC)-limit error-free operation is obtained, and the power penalties of transmission are less than 1 dB.