We report on the improvements of an InGaAs/InP quantum wire (QWR) laser leading to a new concept of a single QWR laser. Its index/gain guiding structure consists of a vertical waveguide in combination with a laterally patterned semi- insulating current blocking layer with an additional oxide layer, which is realized by a simple self-aligning sub-micrometers lithography step. A further improvement of the structure is possible by reducing the thickness of InP buffer layers, which were necessary due to technological reasons. One InP buffer layer may be omitted completely by increasing the growth temperature from 600 degree(s)C to 640 degree(s)C. By employing metal-organic vapor-phase epitaxy we found a significant increase of In-content of the QWRs at the raised temperature.