Combining MEMS FTIR Spectrometer and Widened-Spectrum Mode-Locked Fiber Laser for Gas-Sensing

Mode-locked fiber lasers are characterized by having high peak power and brightness, in addition to a high spatial coherence with output confined in the small diameter of a single mode fiber. However, due to their relatively narrow spectral width, their use in spectroscopic applications is hindered. In this work, we use a section of low-cost non-zero dispersion-shifted fiber (NZDSF) (ITU-T G.655) to widen the spectral width of a mode-locked laser, rendering it suitable for use in gas-sensing. The NZDSF has a relatively low dispersion, allowing the non-linearity of the fiber to dominate its dispersion, which causes an increase in the spectral width [1]. This broad spectrum is used in conjunction with a microelectromechanical system (MEMS)-based miniaturized Fourier transform infrared (FTIR) spectrometer [2, 3] to detect CO
₂
gas inside a multi-pass gas cell.