Low-loss High-dispersion Technology; Enabling Component for Ultrafast Real-time Imaging using Amplified Dispersive Fourier Transform

摘要

The ability to control chromatic dispersion is in serial time encoded amplified microscopy (STEAM) where dispersion is used to slow down fast signals so that they can be digitized in real-time. Unfortunately, these dispersive elements suffer from one or more of the following restrictions: (i) limited operational bandwidth, (ii) limited total dispersion, (iii) low peak power handling, or (iv) large spatial footprint. This project was aimed at identifying new dispersive device technologies that can operate at any spectral range and with low loss. Here we report new type of tunable dispersive device, which overcomes these limitations by leveraging the large modal dispersion of a multimode waveguide in combination with the angular dispersion of diffraction gratings to create chromatic dispersion. We characterize the device s dispersion, and demonstrate its ability to stretch a sub-picosecond optical pulse to nearly 2 nanoseconds in 20 meters of multimode optical fiber. Using this device, we also demonstrate single-shot, time-wavelength atomic absorption spectroscopy at a repetition rate of 90.8 MHz. This technology will allow STEAM based imagers, as well as other systems that exploit group velocity dispersion such as chirped pulse amplifiers, to operate at wavelengths where conventional dispersive elements are incapable of operating.