The present invention provides methods, systems, and apparatus of improved fiber-based optical parametric oscillators (FOPOs). These oscillators can be used in the creation of short pulsed laser radiation, which are useful in numerous applications, such as characterization of materials and molecules. A relationship between fiber length and performance is realized, where shorter lengths counterintuitively provide greater power and width of output bands. This relationship is used to develop improved FOPOs. For example, fibers of 10 cm or less may be used to obtain superior performance in terms of wavelength tunability (e.g. bandwidth of 200 nm and greater) and output power (e.g. pulse power of 1 nJ). Other realized relationships between length and wavelength position of output bands are also used to select the wavelength range output from the FOPO. The diameter of the fiber may be selected to provide positioning (e.g. a centering) of the range of attainable output wavelengths.