A hybrid vertical cavity laser (100, 600) for a photonic integrated circuit, the laser comprising: a first low refractive index layer; a second low refractive index layer (140, 640) on the first low refractive index layer; a grating mirror between the first and second low refractive index layers, (112, 140); an optical waveguide optically coupled to one side of the grating mirror in a first direction; a Group III-V semiconductor layer on the second low refractive index layer, the Group III-V semiconductor layer including an active layer; a top mirror on the Group III-V semiconductor layer; and characterised in that: the grating mirror includes a plurality of bars that are spaced apart from each other and arranged in a two-dimensional array, the first and second low refractive index layers (112, 140) each having refractive indices that are lower than a refractive index of the plurality of bars; and the hybrid vertical cavity laser further comprises a third low refractive index insulator layer having a lower refractive index than silicon and than the bars, which is arranged between the plurality of bars of the grating mirror and the second low refractive index layer (140, 640), wherein a pattern of the third low refractive index insulator layer corresponds to a pattern of the plurality of bars (522, 124). a first low refractive index layer; a second low refractive index layer (140, 640) on the first low refractive index layer; a grating mirror between the first and second low refractive index layers, (112, 140); an optical waveguide optically coupled to one side of the grating mirror in a first direction; a Group III-V semiconductor layer on the second low refractive index layer, the Group III-V semiconductor layer including an active layer; a top mirror on the Group III-V semiconductor layer; and characterised in that: the grating mirror includes a plurality of bars that are spaced apart from each other and arranged in a two-dimensional array, the first and second low refractive index layers (112, 140) each having refractive indices that are lower than a refractive index of the plurality of bars; and the hybrid vertical cavity laser further comprises a third low refractive index insulator layer having a lower refractive index than silicon and than the bars, which is arranged between the plurality of bars of the grating mirror and the second low refractive index layer (140, 640), wherein a pattern of the third low refractive index insulator layer corresponds to a pattern of the plurality of bars (522, 124). the grating mirror includes a plurality of bars that are spaced apart from each other and arranged in a two-dimensional array, the first and second low refractive index layers (112, 140) each having refractive indices that are lower than a refractive index of the plurality of bars; and the hybrid vertical cavity laser further comprises a third low refractive index insulator layer having a lower refractive index than silicon and than the bars, which is arranged between the plurality of bars of the grating mirror and the second low refractive index layer (140, 640), wherein a pattern of the third low refractive index insulator layer corresponds to a pattern of the plurality of bars (522, 124).