  Nanowire lasers are sought for near-field and on-chip photonic applications
as they provide integrable, coherent and monochromatic radiation. A
wavelength-scale nanowire acts as both the gain medium and the cavity for the
lasing action: the functional performance (threshold and wavelength) is
therefore dependent on both the opto-electronic and crystallographic properties
of each nanowire. However, scalable bottom-up manufacturing techniques often
suffer from inter-nanowire variation, leading to, often dramatic, differences
in yield and performance between individual nanowires. Establishing the
relationship between manufacturing controls, geometric and material properties
and the lasing performance is a crucial step towards optimisation, however,
this is challenging to achieve experimentally due to the complex
interdependance of such properties. Here, we present a high-throughput
correlative approach to characterise over 5000 individual GaAsP/GaAs multiple
quantum well nanowire lasers. Fitting the spontaneous emission provides the
threshold carrier density, while coherence length measurements measures
end-facet reflectivity. We show that the lasing wavelength and threshold are
intrinsically related to the width of a single quantum well due to quantum
confinement and bandfilling effects. Unexpectedly, there is no strong
relationship between the properties of the lasing cavity (facet reflectivity
and distributed losses) and the threshold: instead the threshold is negatively
correlated with the non-radiative recombination lifetime of the carriers. This
approach therefore provides an optimisation strategy that is not accessible
through small-scale studies. The quality and width of the quantum wells limit
the threshold of these nanowire lasers, rather than the cavity quality.
