Bistable optical device comprising a lightly doped optical fibre

Claim 1

A bistable optical device comprising: An optical cavity bounded by input and output reflecting means located respectively at an input end and an output end thereof, said optical cavity including therein, in series combination, both laser means and saturable absorber means; together with a first pumping source, arranged relative to the input end of the optical cavity to inject pumping radiation therein and to cause said pumping radiation to propagate along said optical cavity from said input end to said output end; also including a second pumping source and optical fiber coupler spliced to an optical fibre and is disposed within said optical cavity cooperative therewith to couple additional optical power into said laser means in which said laser means and said saturable absorber means are constituted by a common single-mode optical fibre, which optical fibre includes an active dopant selected from rare-earth and transition metal ions capable of providing a three-level lasing transition, said optical cavity is tuned to said three-level lasing transition, and said active dopant is active to provide both stimulated emission and saturable absorption corresponding to said transition.