Embodiments relate generally to electromagnetic radiation detector devices, systems, and methods using a planar Golay cell. One device includes a cell body forming a cavity therein, wherein the cavity includes a wavelength selective absorber having a predetermined absorption spectral range and the cavity is filled with a gas and a pressure sensing element fluidly connected to the cavity to measure a change in pressure within the cavity. One device may include a plurality of planar Golay cells, wherein the cell bodies of the Golay cells are stacked against one another, wherein the pressure sensing elements of the Golay cells are located adjacent to the stacked sides of the cell bodies, and wherein radiation from a single light source is directed through the plurality of Golay cells.