Abstract

The growing demand for increasing the resolution of spectral measurements in various applications stimulates the development of new methods and devices. The best resolution of today’s monochromator-based optical spectrum analyzers is 10 pm (1.25 GHz). This resolution can be enhanced up to ≈0.5 pm (62.4 MHz) using periodic spectral modulation by a sampled fiber Bragg grating [1] or a dispersive element followed by an optical phase modulator [2]. The resolution of widely used broadband techniques such as Fourier transform, cavity-enhanced and cavity-ringdown spectroscopy is mainly limited to tens of megahertz. High-finesse Fabry-Perot interferometers can provide much higher resolution, but they require high flatness and parallelism of mirrors, as well as careful matching between the cavity and input beam and high-precision stabilization. The main disadvantage of Fabry-Perot interferometers is that their working range is limited by free spectral range (FSR).

© 2013 IEEE