Brillouin laser spectrometer based on spectral compression

We introduce a spectrometer design that uses Brillouin lasing to perform broadband spectral compression. This approach enables the entire C-band (optical frequencies covering 4 THz, or 25 nm) be compressed into 230 MHz wide RF spectrum—allowing THz optical spectrum monitored continuously using standard analog-to-digital converter. technique is based on linear dependence of frequency shift wavelength. To use this for analysis, we couple input fiber ring cavity where it acts as an pump, exciting frequency-shifted spectrum. The then referenced copy original heterodyne detection, converting associated with each mode domain. narrow linewidth modes precise measurement individual lines uncertainty 28 (0.2 pm) across band at update rate 200 Hz. simple approach, constructed fiber-coupled telecom components, provides efficient method high-resolution, analysis.