Virtual mesa and spoiler midinfrared angled-grating distributed feedback lasers fabricated by ion bombardment

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It is demonstrated that the suppression of parasitic Fabry–Perot-like lasing modes substantially enhances the beam quality and brightness of wide-stripe angled-grating distributed feedback lasers emitting in the midwave infrared. The direct facet-to-facet gain path is blocked by loss regions that are created by ion bombardment with 900 keV silicon ions. Both virtual mesa structures, in which loss regions bound both sides of the 300-μm-wide angled gain path, and spoiler structures, in which loss is induced only near the facets, decrease the etendue of the output by nearly an order of magnitude, and increase the brightness by up to a factor of 3.