We present a novel spectroscopic method based on a phase-modulated interferometer which is suitable for the high-precision measurement of absorption and index of refraction profiles. A comparison with competing methods, that is with interferometry and FM spectroscopy, is given. The combination of these two methods, the phase-modulated interferometer, is shown to be best suited for experiments aiming at the realization of novel optical media, for example media exhibiting an ultra-large index of refraction or strong dispersion without absorption. The theory of operation and a theoretical and experimental signal-to-noise analysis are presented. Current detection limits for optical phase shift and relative absorption are 1.1×10-5 rad/ and 2×10-5 / , respectively. We demonstrate the effectiveness of this novel technique by investigating the absorption and index of refraction profiles of the 4s21S0-->4s4p1P1 resonance transition at 423 nm in calcium.
Applied Physics B: Lasers and Optics
- Pub Date:
- June 2000
- PACS: 07.65;