Wavelength-tunable ultrafast light sources, with tunability far beyond the gain bandwidth of (rather few) naturally-available laser media, enable a great variety of applications ranging from bio-spectroscopy to safety inspection. Presently available solution of optical parametric generation (OPG) can provide emission extending from ultraviolet (UV) to the mid-infrared (MIR). However the need of mechanical readjustment for wavelength tuning leads to operational reliability issues, and thus limits the applications of OPG outside dedicated optical labs. On the other hand, the simple configuration and operational robustness of supercontinuum (SC) fiber lasers take advantage of simpler fiber technology, but with a high inherent noise figure. In this talk, I will present a simple and cheap fiber technology based on fiber-optic Cherenkov radiation in tapered photonic crystal fibers. This laser technique allows one to resonantly convert the emission wavelength of a standard pulsed laser to a wide continuous range of desired wavelengths, with very low inherent noise, and without mechanical adjustment of any of the elements of the laser.