Long cavity spectral disperser at sub-picometer resolution. Design and analysis

In many applications of spectrometry, a very high spectral resolution is of paramount importance for technologies such as wavelength division multiplexing, femtosecond laser pulse shaping, chemical analysis of gases, or astrophysics observations. A few techniques achieving such goal already exist as listed in the introducing paragraphs. In this article is described a long cavity spectral disperser that is likely to be integrated into a spectrometer and having the potential to attaining unsurpassed spectral resolving power equal to λ/dλ = ten millions or more. The basic relations of its angular dispersion, free spectral range, resolving power, transmission and contrast are established and a preliminary optimized design is presented.