Real-time spectroscopy with subgigahertz resolution using amplified dispersive Fourier transformation

Dispersive Fourier transformation is a powerful technique in which spectral information is mapped into the time domain using chromatic dispersion. It replaces a spectrometer with an electronic digitizer and enables real-time spectroscopy. The fundamental problem in this technique is the trade-off between the detection sensitivity and spectral resolution, a limitation set by the digitizer’s bandwidth. This predicament is caused by the power loss associated with optical dispersion. We overcome this limitation using Raman-amplified spectrum-to-time transformation. An extraordinary lossless −11.76ns∕nm dispersive device is used to demonstrate single-shot gas absorption spectroscopy with a 950MHz resolution—a record in real-time spectroscopy.