Using a multimode fiber as a high resolution, low loss spectrometer

Traditional grating based spectrometers rely on a one-to-one spectral-to-spatial mapping. However, this one-to-one mapping is not required as long as distinct spectral signals are mapped to unique spatial intensity distributions. A calibration step is required to record this complex spectral-to-spatial mapping, but after calibration, the input spectra can be reconstructed simply by measuring the intensity distribution for an arbitrary input spectrum [1]. This approach has enabled a variety of dispersive media to be used in spectrometers, including a disordered photonic crystal lattice [1], an array of Bragg fibers [2], and even a random medium [3]. However, each of these dispersive media suffers high insertion loss, limiting the device performance.