An optical mechanism for a miniaturized spectrometer comprises an input unit, an upper waveguide plate, a lower waveguide plate, and a miniature diffraction grating. The input unit is used to receive an optical signal and direct the optical signal to the interior of the optical mechanism. The upper waveguide plate has a first reflective surface. The lower waveguide plate having a second reflective surface aligned substantially parallel to the upper waveguide plate. The first reflective surface is located opposite to the second reflective surface. An optical channel is formed between the first reflective surface and the second reflective surface, so that optical signal from the input unit can travel in the optical channel. The miniature diffraction grating separates the optical signal transmitted in the optical channel into a plurality of spectral components and directs the spectral components to an image capture module at an end of the miniaturized spectrometer.