Spectrometrists probing the midinfrared with semiconductor lasers have had to be content with the higher noise and spectral width of pulsed operation or else use cryogenic cooling to achieve continuous-wave (CW) operation. A quantum cascade device developed at Applied Optoelectronics Inc. in Sugar Land, Texas, has taken a step toward bridging this problem. The laser, centered at 5.2 µm, still required cooling to 210 K to achieve CW operation at 8 mW, but this is within the ability of less-expensive thermoelectric coolers. The company applied material advances and thermal engineering to know-how it licensed from Lucent Technologies Inc. in Murray Hill, N.J. Engineers at Applied Optoelectronics believe they can demonstrate the same results for 4.6-µm devices.