Superbroadband or multiwavelength transmitter for optical fiber communication systems

This paper describes a novel technical approach to build a multiwavelength laser source for WDM applications. Contrary to conventional tunable laser sources that can switch between different lasing wavelength in a given wavelength band, the superbroadband laser simultaneously emits at multiple wavelengths. The basic idea of this system is to maintain simultaneous lasing operation in an optical active gain medium at different wavelengths. The system uses a novel dispersive cavity. By designing this cavity structure appropriately, the system creates its own microcavities each lasing at a different wavelength within the fluorescence band of the gain medium. The experimental results of the superbroadband and multifrequency lasing are demonstrated on the basis of a LiF:F₂^- color center medium. A simultaneous generation across the whole emission region of the LiF:F ₂^- active medium (1.1-1.24 μm) with efficiency of 15 % and a simultaneous frequency doubling in the visible green-red spectral region (0.55-0.62 μm) was achieved as well as a regime of multi frequency lasing with a special pre-assigned spectral distribution (20 independent lines were obtained and up to hundreds of lines possible) was realized by placing a special mask or image controller into the pump beam. For applications in communications systems a version of this superbroadband laser using a semiconductor active gain material operating in one of the telecommunication wavelength bands around 1.3 or 1.5 μm is proposed