Abstract

There is keen interest in ultrashort-pulse lasers that can operate at visible wavelengths, particularly between 500 and 600 nm, since these would extend the application of two-photon fluorescence microscopy to a wider range of biological molecules [1]. Raman shifting of conventional lasers to access new wavelengths is a common technique, often utilising a cavity around a Raman medium to resonate the Stokes wavelength(s). This has several significant advantages: it improves beam quality; it allows conversion of lower-power pulses and it provides control over the conversion and cascading of the SRS process to second and higher Stokes orders [2].

© 2009 IEEE