The longest wavelength III-V semiconductor laser to date has been realized employing a quantum cascade configuration for the active material. It operates at lambda similar to 19 mu m on interminiband transitions in graded superlattices. The waveguide is based on surface plasmon modes confined at a metal-semiconductor interface. The devices emit peak output powers of 14 mW per facet at 10 K and laser action is achieved up to the maximum temperature of 145 K. (C) 2000 American Institute of Physics. [S0003-6951(00)02341-X].

A pulsed quantum-cascade distributed feedback laser operating at near room temperature was used for sensitive high-resolution IR absorption spectroscopy of ambient air at a wavelength of similar to8 mum. Near-transform-limited laser pulses were obtained owing to short (similar to5-ns) current pulse excitation and optimized electrical coupling. Fast and slow computer-controlled frequency scanning techniques were implemented and characterized. Fast computer-controlled laser wavelength switching was used to acquire second-derivative absorption spectra. The minimum detectable absorption was found to be 3 x 10(-4) with 10(5) laser pulses (20-kHz repetition rate), and 1.7 x 10(-4) for 5 x 10(5) pulses, based on the standard deviation of the linear regression analysis. (C) 2000 Optical Society of America OCIS codes: 140.5960, 280.3420, 300.6320, 010.1280.

The longest wavelength whispering gallery semiconductor disk lasers fabricated tc date are reported. The devices operate at lambda similar or equal to 16 mu m up to a temperature of similar to 120K. They employ the quantum cascade scheme based on interminiband transitions in graded superlattices and are realised in the InGaAs/AlInAs material system.