This paper gives an experimental result on the measurement of the maximum coupling coefficient and the coupling length between the active waveguide and the passive output waveguide in GaAs/AlGaAs integrated twin-guide (ITG) injection lasers prepared by LPE. Very high coupling efficiency between the active and the passive waveguides was experimentally confirmed. The maximum coupling coefficient and the coupling length were measured to be about 90% and 250 µm, respectively. These values were in agreement with theory. At properly chosen parameters, the threshold current density on an ITG-type" laser was as low as 3 kA/cm2 at room temperature.

In this paper, a numerically exact analyzing method is formulated for the diffused optical waveguide which consist of anisotropic or isotropic medium. By this analytical method, the guided modes of the diffused waveguide are determined and a measurement method for the diffusion coefficient is proposed as an application of this analysis. In the case that there is gradient of the dielectric constant, the exact analysis of the TM-modes is ordinarily difficult. In this analysis the index distribution for the anisotropic medium whose optical-axis is perpendicular to the waveguide or parallel to the waveguide-axis is sliced into multi-layers for successive numerical calculation. It is found, from the waveguides can be discussed with the equivalent film-width defined analytical results, that the propagation properties of the diffused in this paper which is analogous to that of the slab-waveguides. The diffusion coefficients and the activation energies of T1 and Ag in a fused-quartz and Vycor glass are measured with application of the analytical results.