Time-wavelength optical sampling spectroscopy based on dynamic laser cavity tuning

Time-wavelength optical sampling (TWOS) is proposed here as a scheme that leverages the advantages of both wavelength-time mapping and ultrafast optical sampling to achieve real-time spectral measurement with simple configurations and slow photodetectors. As a proof of concept, a TWOS spectrometer based on dynamic optical sampling by laser cavity tuning is developed. Real-time absorption spectroscopy with a 0.3-nm spectral resolution and a 60-nm total spectral range (laser limited) is demonstrated at a 150-Hz updating rate. Theoretical analysis and practical limiting factors are discussed in detail. Potential applications of TWOS include spectroscopy, imaging, metrology, and optical sensing. (C) 2018 Optical Society of America.