Abstract: In an optical fiber communication system a pulse reshaper can transform a distorted input light pulse into a reshaped output light pulse. The disclosed pulse reshaper is an all-optical pulse reshaper that comprises an optical waveguide having an effective length, the waveguide connecting the input and the output and comprising optical non-linear material, with a periodic variation of an effective refractive index of the optical waveguide. The optically non-linear material and the periodic variation are selected such that the reshaped output light pulse is a substantially transform-limited output light pulse.

Abstract: In accordance with the invention, an optical switch employs a long-period grating for switching light between alternative optical paths. In essence, the device comprises a variable intensity light source, a length of optical waveguide dimensioned for co-propagating light in two distinguishable modes, and a long-period grating in the waveguide for coupling between the two modes. The waveguide is nonlinear so that the effective refractive index is a function of intensity. As a consequence the coupling produced by the grating is a function of intensity. Thus different levels of light intensity can switch between the separate modes. Advantageously a mode separator is provided for directing light in the two modes onto respectively different optical output paths. A variety of two-mode switches and optical limiters are described, as well as an optical system using the switch.

Abstract: An organic laser according to the invention comprises an electrically pumped source of incoherent radiation with organic active region, and further comprises a waveguide structure that receives the incoherent radiation. The core of the waveguide comprises organic material that absorbs the incoherent radiation and emits coherent radiation of longer wavelength. The laser forms a unitary structure, with the source of incoherent radiation being close to the waveguide core, exemplarily less than 10.lambda. from the core, where .lambda. is the laser wavelength. Exemplarily the laser is embodied in a planar waveguide laser, in a microdisk laser, or in a laser comprising a photonic bandgap structure.