Bridging Theory and Experiment in Virtually Imaged Phased Array (VIPA) Spectrometers

Abstract

Virtually imaged phased array (VIPA) spectrometers provide high resolution and fast acquisition in a compact design, but their performance as dispersive instruments is sensitive to fabrication tolerances, component dimensions, and alignment. Here, leveraging numerical simulations validated by experimental data, we present a framework to identify the parameters that limit VIPA spectrometer resolution. This framework is applied to the construction of a new mid infrared VIPA spectrometer, tested at wavelengths near 4.6 um with both continuous-wave and frequency-comb laser sources, with a resolving power predicted by analytical expressions to be as high as RP = 830 000 (corresponding to a resolution of 78 MHz). Validated numerical simulations, however, provided a more realistic estimate that captures limits set by all the optical components. By correcting aberrations and optimizing alignment, a resolving power of RP = 440 000 (150 MHz) was experimentally achieved, corresponding to 80% of the value predicted by numerical simulation of the entire spectrometer. These results bridge the gap between analytical design expressions and experimental results for compact, high-resolution VIPA spectrometers to enable more efficient fabrication and advanced design across critical areas like applied space optics, line-by-line pulse shaping, and broadband spectral sensors.