REFLECTIVITY-MODULATED GRATING MIRROR

摘要

The invention relates to vertical cavity lasers (VCL) incorporating a reflectivity-modulated grating mirror (1) for modulating the laser output. A cavity is formed by a bottom mirror (4), an active region (3), and an outcoupling top grating mirror (1) formed by a periodic refractive index grating region in a layer structure comprising a p- and a n-doped semiconductor layer with an electrooptic material layer (12) arranged there between. The grating region comprises a grating structure formed by periodic perforations to change the refractive index periodically in directions normal to the oscillation axis. A modulated voltage (91) is applied in reverse bias between the n- and p-doped layers to modulate the refractive index of the electrooptic material layer (12) and thereby the reflectivity spectrum of the grating mirror (1). The reflectivity of the grating mirror (1) can be modulated between a reflectivity with little or no out coupling and a reflectivity with normal out coupling, wherein lasing in the VCL is supported at both the first and the second reflectivity. As the out coupling mirror modulates the output, the lasing does not need to be modulated, and the invention provides the advantage of lower power consumption at high modulation speeds.

主权项

1. A vertical cavity laser with a reflectivity-modulated grating minor, comprising:
a cavity formed by a first and a second reflector formed in different layers on a substrate and an active region formed in the cavity, the cavity being arranged to support light oscillation along an oscillation axis normal to the substrate, wherein the first reflector is an outcoupling grating mirror formed by a refractive index grating region in a layer structure comprising a p-doped semiconductor layer and an n-doped semiconductor layer with an electrooptic material layer arranged there between, said grating region comprising a 1D or 2D grating structure formed by a plurality of perforations so that a refractive index changes periodically or nonperiodically in the grating region in directions normal to said oscillation axis; and electric contacts to apply electrical bias to the electrooptic material layer and to the active region independently, wherein the p-doped semiconductor layer and the n-doped semiconductor layer of the grating minor act as electric contacts for the electrooptic layer.