Far-infrared (FIR) and submillimeter astronomy is a crucial frontier in modern astrophysics, providing unique insights into the formation and evolution of cosmic structures that remain hidden at other wavelengths. This thesis presents the development of advanced spectroscopic instrumentation designed to push the boundaries of observational capabilities in FIR/Submm astronomy. By addressing key limitations in current technology, these instruments enable groundbreaking studies of galaxy formation, planetary system evolution, and the chemical composition of astrophysical environments. At the core of this work is the development of high-performance spectrometers for two state-of-the-art observatories: the Epoch of Reionization Spectrometer (EoR-Spec) to be used on the Fred Young Submillimeter Telescope (FYST), a 6 meter aperture telescope sited at an elevation of 5600 meters on Cerro Chajnantor, and the Virtually Imaged Phased Array (VIPA) on the Planetary Origins and Evolution Multispectral Monochromator (POEMM), a NASA mission on with a 1.8 meter telescope suspended at 35 km elevation on a long duration balloon. EoR-Spec is designed to study star and galaxy formation and the growth of structure from the epoch of reionization, when the first luminous sources began to ionized the neutral intergalactic medium to cosmic noon when the peak of star formation per unit co-moving volume occurred. At the high site, FYST leverages exceptionally dry atmospheric conditions to conduct sensitive measurements in the millimeter and submillimeter regimes. POEMM will explore the complex chemistry of protoplanetary disks and planetary atmospheres, offering critical insights into the processes that shape planetary systems. This thesis bridges technological innovation with scientific discovery, demonstrating how novel spectrometer designs can enhance instrument performance and expand the reach of FIR/Submm astronomy. By overcoming challenges related to spectral resolution and detector sensitivity, the instruments presented here open new pathways for investigating the Universe’s most elusive phenomena. The advancements documented in this work not only enhance current observational capabilities but also lay the groundwork for future missions that will continue to redefine our understanding of the cosmos.