Abstract

Semiconductor laser diodes operating at visible and near infrared wavelengths have revolutionised electro- optic applications because of their small size, high spectral purity, high modulation frequency, ruggedness and long lifetime. There is considerable interest in longer wavelength devices operating in the mid-infrared for several applications, including remote detection of pollutant and toxic gases, general spectroscopy, eye- safe range finding and secure communications. There are several alternative material systems and device structures for lasers in the mid infrared band, including intersubband devices in GaInAs/AlInAs; strained or unstrained type II superlattices or quantum wells in several InAs based systems; and a variety of II-VI and IV-VI bulk or quantum well structures. We have chosen to develop lasers based on InSb, which is the only direct gap III-V system for wavelengths in excess of 4μm and for which very high quality epitaxial growth and fabrication techniques exist.

© 1996 IEEE