Grating-coupled surface emitting quantum cascade ring lasers

Abstract

We report on the fabrication and operation of quantum cascade ring lasers providing grating-coupled surface emission. The devices exhibit tunable far fields, ranging from spot- to ring-shaped symmetric beam cross sections, depending on the grating period. This—along with threshold current densities as low as for comparable Fabry–Pérot lasers—demonstrates the compatibility of reduced beam divergence and two-dimensional integrability, resulting in an attractive light source for applications in midinfrared spectroscopy and imaging.

Time-resolved spectral characterization of ring cavity surface emitting and ridge-type distributed feedback quantum cascade lasers by step-scan FT-IR spectroscopy

“…The lasers used in this study were based on the material published in [15] and processed as described in [16]. The experimentally obtained temperature tuning rate was −0.085 cm −1 /K [17].…”

Ring cavity induced threshold reduction in single-mode surface emitting quantum cascade lasers

“…This type of resonator allows for vertical emission by incorporating second-order gratings on top of the laser. 16 Moreover, it was shown that the beam divergence can be significantly reduced in MIR and THz QCLs by utilizing such a circular cavity design. [17][18][19] The QCL structure used in this work is based on an In 0.53 Ga 0.47 As/ In 0.52 Al 0.48 As two-phonon resonance design for an emission wavelength of Ϸ 8.05 m, as in Ref.…”

Grating-Induced Beam-Tuning in Quantum Cascade Ring Lasers

“…We present QC ring lasers that provide both surface emission as well as the capability of producing circularly symmetric far fields [6]. Several 18 µm wide ring lasers, with an outer radius of 200 µm, that utilize rectangular dry-etched surface gratings with different periods were processed by means of combined electron beam and optical lithography.…”