The properties of a 1.3μm GaInNAs Double Quantum Well (QW) ridge waveguide (RWG) laser have been systematically studied for GaAs based uncooled long wavelength lasers. The threshold current, transparency current, optical gain, internal loss and quantum efficiency characteristics were assessed by light-current (L-I) measurement using devices with different geometries. Measurements of gain spectra versus injection current and temperature were taken and used to analyze GaInNAs as an active material in terms of gain, loss and transparency. The experimental observations are discussed. The results are compared with those obtained from lasers made by other conventional materials. The high characteristic temperature (T0=155K from 20°C to 75°C) and comparable stimulated emission to InP based lasers offer the promise of application as a light source for low cost data communication systems.
Early development work in the design of optical power splitters, likely influenced by similar construction in the microwave regime, placed heavy emphasis on Y-branch designs with the output waveguides immediately branching from the input waveguide at non-zero angle. This design approach, which is still prevalent, is fundamentally flawed from the perspective of both optical power flow and fabrication, as it leads to significant excess loss and/or a large
statistical variance. If inherent broadband response is not a critical requirement, directional-coupler or multimode-interference splitters are usually chosen instead. We demonstrate, choosing a minimal function perspective where the optical design is sensitive
to the smallest possible set of critical fabrication parameters, that robust and low-loss Y-branch designs are indeed possible. The minimum gap width between waveguides being the critical parameter, we reveal the dependence of the irreducibly simplest design on all
elements of the parameter space, as they relate to the critical one. In so doing, we show that the concept of bending angle is irrelevant.