In this work, binary phase masks are designed and implemented for use with a photoconductive terahertz (THz) emitter in order to shape the frequency response of the emitted THz waveforms. Theoretical and experimental results are applied to study the system. The theoretical results are presented in the form of both numerical simulations (to characterize and uniquely identify the underlying time-delayed photogeneration and resulting charge-carrier dynamics) and a simplified model (to conceptualize the system). The theoretical and experimental results are found to agree. It is ultimately shown that the phase delay through the binary phase mask can be used to preferentially allocate power into bands within the THz spectrum. Such results can lay the groundwork for future studies needing precise control of power within the THz spectrum. Index Terms-frequency response, optical beams, photoconductivity, terahertz radiation. I. INTRODUCTION VER the past decades, ultrafast pulsed lasers have enabled numerous advances in pure and applied studiesmany of which rely upon the effective emission and detection of terahertz (THz) radiation [1], [2]. This THz radiation, spanning 0.1-10 THz, has traditionally been difficult to emit and detect [3]-[6], due to the low photon energy, but the advent of sub-picosecond pulse durations with modern ultrafast pulsed lasers has enabled access to the THz spectrum. We now see THz radiation applied to communications, given its high carrier frequencies [7]-[9], biomedical imaging, given its low (and typically safer) photon energies [10], [11], and spectroscopy, given its extreme sensitivity to molecular absorption lines [12], [13].