Abstract
Recently, our group presented the surface emitting ring cavity quantum cascade laser (QCL). This kind of light source shows lower thresholds, higher slope-efficiencies and narrower emission beams as compared to equivalent Fabry-Perot devices. Typically, such lasers show a doughnut-shaped, rotational symmetric far field with azimuthal polarization. When the excited modes in the cavity are off-resonance to the DFB grating, the light is emitted under a broader angle. This leads to a widening of this `doughnut' and the polarization of the far field switches to radial polarization. Additionally, we present ring-QCLs with linear polarized far fields. For this task, devices with PI-shifts in the grating period were used. The opposing fields in the ring resonator interfere constructively in the centre of the far field. We observed a central lobed far field, where pure linear polarization in this central lobe was measured. To extend this polarization property to the entire far field, a wire grid polarizer was fabricated onto the substrate with the wires perpendicular to the favoured polarization direction. The devices were optimized for substrate emission.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.