High power semiconductor lasers have the advantages of high electro-optical efficiency, easy modulation, small size and light weight. Thermal effects can reduce the laser output power, electro-optical conversion efficiency, and even reduce the service life. High-power semiconductor laser package requirements for transition heat sink are mainly two aspects, low thermal resistance and low thermal mismatch. According to Fourier's law, the thermal resistance of the laser is inversely related to the thermal conductivity, the higher the thermal conductivity of the heat sink material, the more effectively reduce the thermal resistance of the device.
Compared with aluminum nitride transition heat sink with thermal conductivity of 230W/(K-m), diamond heat sink has high thermal conductivity (up to 1800W/(K-m)), which can significantly improve the heat dissipation of the laser as a transition heat sink for high power semiconductor lasers. Diamond film with thickness greater than 150um and thermal conductivity greater than 6W/(K -cm) as thermal sink can significantly reduce the laser thermal resistance effect. Compared with the device using Cu heat sink, a diamond film heat sink with thickness 350~400um and thermal conductivity between 12~14W/(K -cm) can reduce the thermal resistance by 45~50% and increase the optical output power by 25%.