Experimental investigation into femtosecond fiber ring laser with passive mode locking

Abstract

A passively mode‐locked Er3+‐doped fiber ring laser is experimentally investigated, with the emphasis on its practical design by considering the effects of ring cavity length, pumping light power, and optical amplification on the femtosecond optical pulses obtained. It is shown that the designed fiber ring laser can operate at the center wavelength of 1550 nm to produce a train of periodic optical pulses with full width at half maximum (FWHM) of 270 fs, repetition frequency of 20 MHz, and average output optical power of 146 μW. The resulting femtosecond optical pulses are then amplified by using three kinds of Er3+‐doped optical fibers with different lengths and Er3+‐doped concentrations, respectively, while employing the same pumping laser. In the experiments, both the FWHM of amplified optical pulses and the amplifier gain are measured under different conditions. The optimization of optical pulse width is also carried out in terms of pumping light power. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 63–67, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23985