Fig. 1

Anatomy of microtaper spectrometers. a Schematics of microtaper spectrometer. b, c Side-view and top-view of the leaky mode patterns from a microtaper shines on the substrate. The wavelength of the incident laser used here is 600 nm. d Photo of a fabricated microtaper spectrometer. e, f Scanning electron microscope images of the microtaper on the CIS. g Fiber transmission curves versus the taper parameter. The 4 fibers are tapered with elongation (x) of 2.72 mm, 3.20 mm, 4.64 mm and 7.76 mm respectively. By carefully control the shape of the microtaper, the incident power can be transported to the leaky mode pattern with near 100% efficiency. h Fiber transmission as a function of interaction length. The interaction length is the contact length of the tapered fiber waist region and the CIS. The 4 fibers are tapered with elongation (x) of 5 mm, 6 mm, 7 mm and 8 mm respectively. The power projected from the microtaper can also be tuned by changing the interaction length