Vernier frequency sampling: a new tuning approach in spectroscopy-application to multi-wavelength integrated path DIAL

摘要

We present novel frequency tuning methods for broadband mid-infrared spectroscopy that take advantage of the unique frequency sampling properties of our recently developed "nested dual-cavity doubly resonant optical parametric oscillator" (NesCOPO). These methods, referred to as Vernier frequency sampling, enable mode-hop tuning with an adjustable virtual-cavity intermode spacing. Both frequency resolution and span are widely adjustable and can be tailored to fulfill the requirements either for broadband spectroscopy (>50 cm~(-1) spectral coverage) at low resolution or for high resolution (<0.01 cm~(-1)) narrow band spectroscopy. The technique is applied to short-range (10 to 30 m) atmospheric CO_2 measurements at 4.2 μm using integrated path differentia] absorption LIDAR.