Abstract: The present application provides a semiconductor Fabry-Perot dual mode lasing device having terahertz characteristics resulting in significant advantages over the prior art including for example operation at room temperatures and the absence of re-growth processing requirements.

Abstract: Disclosed is a laser (10) comprising a lasing cavity with a lasing medium and primary optical feedback means in the form of a facet (17) at either end of the cavity, the laser cavity defining a longitudinally extending optical path; and secondary optical feedback means formed by a plurality of refractive index perturbations (16, 22) in the laser cavity, each perturbation defining two interfaces (20, 21); characterized in that, for at least one perturbation, only one of the two interfaces contributes to optical feedback along the optical path. The present invention relaxes the lithographic tolerances for making single longitudinal mode devices and improves performance characteristics.

Abstract: The present application is directed at providing a new lasing device having increased production yields over other single mode laser devices. In particular, a semiconductor lasing device is provided having at least two lasing devices formed on a common substrate. The lasing device is arranged so that in use a preferred lasing device is operational and remaining lasing devices are redundant. This redundancy improves the production yield since only one of the lasing devices needs to function correctly as the others are unused.

Abstract: The present invention relates in general to semiconductor light emitting devices and in particular to methods of altering the spatial emission patterns of such devices. A known problem with these prior art light emitting devices (and laser diodes in general) is that their far-field emission patterns are elliptical and astigmatic in nature. The present invention addresses this problem by refractive index perurbations in the semiconductor device aligned in a direction substantially transverse to the light emission direction to achieve a desired spatial distribution of the emission.