GaAs/AlGaAs rooftop reflector laser for optoelectronic integrated circuits

Abstract

GaAs/AlGaAs RTR laser was suggested as an integrable laser for optoelectronic integrated circuits (OEICs). Concept of the device was studied and the device was fabricated using GaAs material system. Effects of lateral inversion on the fundamental characteristics were investigated using beam propagation method. Monolithic integration processes using selective epitaxy technique were also studied. A roof prism and a cube-corner prism are two-dimensional and three dimensional retroreflectors, respectively. These prisms are used as the alignment-insensitive cavity elements of the solid-state and gas lasers for adverse environments such as field operation and operation on a vibrating support. A roof prism can be formed in the compound semiconductors such as GaAs and InP taking advantage of the anisotropic wet chemical etching. For application of this prism to the semiconductor laser diode, the properties of the rooftop reflector(roof prism as a reflector) and its resonator are studied first. Then, the operation of GaAs/AlGaAs RTR laser consisting of a cleaved facet and a GaAs rooftop reflector was demonstrated. The laser operation was confirmed by observing the narrowing of the spectral width as the injection current inceased. The TE modes were preferred to the TM modes and typical threshold current of the oxidestripe laser with stripe width of 20 $\mu$m and cacity length of 200 $\mu$m was in the range 180-200 mA. The results also showed that the rooftop reflector with the reflectivity exceeding 0.9 could be readily obtained. Next, the stripe-geometry GaAs/AlGaAs RTR laser was numerically studied. The axial beam incident upon the rooftop reflector of the laser is retroreflected by it and experiences lateral inversion and phase shift depending on the incident angle. This was modelled numerically and studied employing beam propagation method. From the results we can see that a perfect RTR acts as a plane mirror with power reflectivity 1.0 and other characteristics are ...