Introduction

Over the past few years, new optical fibers with enhanced nonlinearity and tailored dispersion (Russell 2003; Knight 2003) have been providing a constantly growing platform for the development of advanced fiber-format devices and components for optical metrology (Jones et al. 2000; Udem et al. 2002), ultrashort-pulse laser technologies (Zheltikov 2007a), biomedicine (Hartl et al. 2001), quantum optics (Rarity et al. 2005), spectroscopy (Sidorov-Biryukov et al. 2006), and microscopy (Paulsen et al. 2003). Unique options offered by photonic-crystal fiber (PCF) technology (Russell 2006), such as dispersion management through fiber structure engineering (Reeves et al. 2003) and enhancement of optical nonlinearity due to a strong field confinement in a small-size fiber core (Fedotov et al. 2001), have been pushing the frontiers of fiber optics, allowing the creation of efficient sources of supercontinuum radiation (Ranka et al. 2000; Dudley et al. 2006; Zheltikov 2006), novel compact fiber lasers (Lim et al. 2002; Limpert et al. 2006), as well as frequency converters (Akimov et al. 2003), pulse compressors (Südmeyer et al. 2003), fiber components for biomedical optics (Flusberg et al. 2005a, 2005b), and optical sensors (Monro et al. 2001).

In the rapidly expanding field of nonlinear microscopy and spectroscopy, PCFs have been shown to possess a tremendous potential for making laser microscopes and spectrometers simpler and much more compact through the replacement of wavelength-tunable laser sources, such as optical parametric amplifiers and dye lasers, by a specifically designed segment of fiber.