High-power operation of 1cm laser diode bars on funryu heat sink cooled by fluorinated-refrigerant

We investigated the properties of fluorinated refrigerants for high-power laser diode bars mounted on a funryu heat sink. The thermal conductivity of fluorinated refrigerants is about ten times lower than that of water, but they are less corrosive to funryu heat sinks. Using 3M's "Fluorinet" FC77 and "Novec" HFE-7300 and comparing them with water as refrigerants, we developed a new fluorinated refrigerant cooling device that is suitable for removing heat from highpower LDs and LD modules. This device achieved CW light-output power from a 1-cm LD bar equivalent to that for a cooling device using ion-exchange water. With HFE-7300 as the refrigerant, we achieved over 100 W of output power at a drive current of CW 120 A and over 1.5 kW for a stacked-LD module operated at a constant current of 55 A in continuous-wave (CW) mode. High-power LD bars subjected to lifetime testing under these conditions have been successfully running for over 15,000 consecutive hours.