Long range correlations in a 97% excitonic one-dimensional polariton condensate

5 pages, 3 figuresInternational audienceWe report on the measurement of first-order spatial correlations on a one-dimensional 97% excitonic polariton condensate, excited in cooled ZnO microwires by nonresonant optical pulses. We find that, thanks to the tiny 3% photonic fraction, a coherence length as large as 10 μm can build up, i.e., orders of magnitude larger than any reported so far for an ultracold exciton gas. Based on a driven-dissipative mean-field model we show that the decay of correlations is mainly due to a shallow disorder and driven-dissipative conditions