An additive {hacek over (S)}olc filter (ASF) includes i) a first polarizer for receiving an input light, such as from a monochromatic light source, and transmitting a first polarized output, ii) at least one birefringent plate positioned to receive the first polarizer output and transmit an output with wavelength-dependent polarization state, and iii) a second polarizer for receiving the plate output and transmitting a second polarized, filtered output. An ASF spectroscopy system includes the ASF; a monochromatic light source input, e.g. a laser; a sample chamber for exposing a sample to the second polarized, tuned output and generating a signal characteristic of the sample that is filtered by the ASF; and a detector for acquiring the characteristic signal.