Compact fiber lasers for stimulated Raman scattering microscopy

The widespread use of coherent Raman scattering (CRS) microscopy outside of research laboratories has been hindered by the lack of suitable low cost, compact, and robust laser sources. It is thus important to develop these laser sources. This chapter reviews our work on the development of compact fiber lasers for CRS microscopy. The first step toward an all-fiber source of pulses for use in coherent anti-Stokes Raman scattering (CARS) imaging is a high-power picosecond (ps) fiber source that can be used to pump a solid-state optical parametric oscillator (OPO) to generate two synchronized ps pulse trains suitable for CRS microscopy. The next laser system that we have developed is an all-fiber source that provides two narrowband ps pulse trains that have been shown to provide good CRS microscopy performance. This laser design has also been commercialized and thus proven to be compact and robust enough for real applications in clinical settings. However, this laser is suitable only to excite molecules in the C H window. To address this challenge we describe our third fiber laser design concept based on four-wave mixing (FWM) in an optical fiber that can provide widely tunable and synchronized ps and femtosecond (fs) pulses suitable for CRS imaging. The most recent and last, laser system that we have developed is also an all-fiber source that generates two synchronized, broadband, chirped pulses for CRS microscopy based on spectral focusing. Detailed description and performance characteristics of this laser source are introduced in this chapter as well.