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A compact packaging module for direct liquid cooling of room-temperature quantum cascade lasers is implemented. The light was coupled out of the hermetically sealed package through a mid-infrared fibre epoxy-bonded to the laser. The threshold current reduces by ∼10%, compared to convectional substrate-side cooled lasers when using low boiling temperature (boiling point (b.p.)=34°C) 3M HFE-7000 coolant. No reduction was observed with high boiling point 3M FC-77 (b.p.=97°C) coolant.