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We demonstrate a monolithic Quantum Cascade Laser array. We show phase-locking and single-mode emission at =8.4m. It consists of narrow ridges buried into InP:Fe. Phase-locking is provided by evanescent coupling between adjacent ridges. This -structuration is simultaneously an answer to the excessive heating and poor beam quality of broad area lasers. First, it increases the surface of exchange between the multi-layer active region and the InP:Fe, which presents a higher thermal conductivity. Secondly, by choosing carefully the width of emitters and the distance between them, we insure phase locking and control of the supermode emission. We have investigated 2m wide emitters. In order to study the behavior of evanescent coupling, we have chosen spacing from 1 to 8 microns. The number of emitters ranges from 1 to 64. Technological feasibility was demonstrated up to 64 emitters, and lasing operation up to 32 emitters. We have obtained a pure dual-lobe far-field pattern as expected from an anti-symmetrical supermode. The width of each lobes narrows with an increasing array size as expected from the diffraction theory. The beam quality is insensitive to the injective current. The optical power scales linearly with the number of emitters.