BUTT-COUPLING LOSS OF 0.1DB INTERFACE IN INP/INGAAS MULTIPLE-QUANTUM-WELL WAVE-GUIDE-WAVE-GUIDE STRUCTURES GROWN BY SELECTIVE-AREA CHEMICALBEAM EPITAXY/

The lateral coupling of waveguiding structures in both [011] and [<0(1 )over bar>1] directions is studied using embedded selective area epita xy by chemical beam epitaxy. All growth steps are carried out under th e same growth conditions on (100) InP substrates misoriented by 0.5 de grees towards (111)B. Both planar and selectively grown material exhib its bright luminescence and narrow PL linewidths (8 meV FWHM at 4 K), up to the lateral junction. Moreover, no degradation of the original m aterial properties is observed after regrowth. SEM images show very fl at layers and excellent lateral coupling for all four types of junctio ns. After reactive ion etching of waveguide ridges, the optical coupli ng losses have been determined using a Fabry-Perot setup at 1530 nm (T E polarization). Values of 0.1 dB/interface with excellent uniformity are presented. From our results we conclude that, by optimization of t he sample preparation prior to regrowth, values of 0.1 dB/interface ca n be obtained reproducibly for both perpendicular coupling directions.