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(Ga,In)(N,As) laser structures using distributed feedback

Tombling, C. (2002) (Ga,In)(N,As) laser structures using distributed feedback. WO/2002/045221.

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Abstract

A lasing structure comprises a distributed feedback grating associated with the active region, the grating defined by a periodic structure of quantum well intermixing. This quantum well intermixing (QWI) can be caused by focussed ion beam (FIB) implantation to the quantum well (QW) or multi-quantum well (MQW) active area. Subsequent annealing of the FIB damage will leave local periodic adjustments to the energy levels in the active region, providing the necessary DFB/DBR grating. Alternatively, or in addition, this periodic QWI structure or another periodic variation can be separated from the active region but associated therewith. For example, a QW or MQW structure which overlies the active region will carry the evanescent part of the waveform that is propagating in the active region. A periodic QWI structure in this region will thus affect the waveform. Other means by which this can be achieved are a periodic variation in the dopant concentration, for example created by FIB implantation or masked exposure to an ion beam or the like, a periodic variation in the material of the overlying layers, such as between semiconductor and insulator, and a periodic QWI structure in a QW or MQW structure overlying the active region.