Optical parametric oscillator (OPO) is a kind of light source similar to a laser but based on parametric gain from amplification in a nonlinear medium rather than from stimulated emission. It features wide frequency tunability and high power narrow linewidth output, which enables its application to laser spectroscopy and atom-light interaction. Although OPOs could provide two synchronized pulse trains for coherent anti-Stokes Raman spectroscopy (CARS) imaging, they remain bulky and sensitive tools requiring careful alignment, making these devices unpractical for surgical situations. Thus, all-fiber source for coherent Raman imaging have generated interest among clinical researchers and doctors. Thanks to recent advances in the understanding of nonlinear pulse evolution in optical fibers and engineering of PCF structures, fiber-based OPOs have achieved performance comparable to conventional solid-state devices. This thesis discussed the previous effort towards an all-fiber source of pulses for use in CARS imaging, as well as principles behind picosecond pulse generation and coherent Raman imaging. An all-fiber OPO pumped by commercial solid state laser and divided pulse amplifier is demonstrated based on frequency conversion of picosecond pulses through four-wave mixing process in customized photonic crystal fiber. This will be another step further towards an all-fiber device for coherent Raman microscopy.