Direct liquid cooling of room-temperature operated quantum cascade lasers

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