What wavelengths of light specifically affect the type of film used in
the first movie containing an variable-density optical audio track? I
am specifically interested in the chemical composition of the optical
audio track.

From what I know, most of the more modern films are unaffected by red
light.

I'm thinking of a theoretical device using analog audio recording on
VD optical tracks containing the oldest film chemical composition. The
source of light are multiple laser beams consisting of wavelengths
that could record the audio onto the film. Each beam has a different
wavelength. The beams are then mixed together to get a single beam of
all the necessary wavelengths. The beam then shines onto the film to
record the audio.

I don't have much of an application here. I'm just in it for the
science.