Title :
Low-threshold grating-coupled surface-emitting lasers with etch-stop layer for precise grating positioning
Author :
Kjellberg, Torgil ; Hagberg, Mats ; Eriksson, Niklas ; Larsson, Anders G.
Author_Institution :
Dept. of Optoelectron. & Electr. Meas., Chalmers Univ. of Technol., Goteborg, Sweden
Abstract :
The authors discuss the operation of InGaAs/AlGaAs grating-coupled surface-emitting lasers with threshold-current densities as low as 118 A/cm/sup 2/, to the best of our knowledge the lowest reported for a surface emitter. The low threshold-current density is the result of high reflectivity and low absorption gratings in conjunction with a lateral effective refractive index step in the gain section. The gratings were fabricated using electron-beam lithography and chemically assisted ion-beam etching, producing uniform rectangular gratings. A thin etch-stop layer incorporated in the epitaxial structure made it possible to combine precise control of the grating position with a strained-layer SQW-GRINSCH structure for optimum low-threshold currents.<>
Keywords :
III-V semiconductors; aluminium compounds; diffraction gratings; electron beam lithography; gallium arsenide; indium compounds; reflectivity; refractive index; semiconductor lasers; sputter etching; InGaAs-AlGaAs; InGaAs/AlGaAs; SQW-GRINSCH structure; chemically assisted ion-beam etching; electron-beam lithography; epitaxial structure; etch-stop layer; gain section; grating position control; high reflectivity; lateral effective refractive index step; low absorption gratings; low-threshold grating-coupled surface-emitting lasers; optimum low-threshold currents; precise grating positioning; semiconductor laser diodes; strained-layer; surface emitter; thin etch-stop layer; threshold-current densities; uniform rectangular gratings; Absorption; Chemicals; Etching; Gratings; Indium gallium arsenide; Lithography; Reflectivity; Refractive index; Strain control; Surface emitting lasers;
Journal_Title :
Photonics Technology Letters, IEEE
