We describe the first operation of an actively mode-locked Er fiber laser at 1.56 μm, Short pulse laser sources operating In the 1.5-μm spectral range are needed for two reasons. First, current fiber optical communication systems operate in this spectral region because of the low loss of silica fibers. Second, 1.56 μm falls in the region of the negative group velocity dispersion (GVD) of silica. It is well known that by combining the effects of a Kerr nonlinearity to produce a frequency chirped pulse and negative GVD, significant pulse compression can be achieved. The laser we describe is of particular significance because it has all the ingredients needed to produce significant nonlinear propagation effects. In addition to operating at a suitable wavelength, the doped silica fiber already Incorporates the Kerr nonlinearity and negative GVD. Thus, in contrast to other nonlinear laser systems1 which introduce an external cavity to produce the nonlinearity, in this laser the necessary nonlinear element is an integral part of the laser cavity. Currently the pulse peak powers in our laser are approaching the level at which nonlinear effects become significant.
© 1989 Optical Society of AmericaPDF Article