Abstract
Interband cascade lasers (ICLs) [1, 2] combine two concepts for semiconductor lasers, in particular the long carrier lifetime of photodiodes together with the voltage-efficient cascading of the quantum cascade laser. The low threshold power makes them very attractive for mobile systems used for spectroscopy, process control or medical applications. To date no suitable overgrowth process exists for GaSb-based ICLs, which prohibits the usage of a top-grating etched into the cladding layer. Single-mode emission from a ridge facet has been achieved via sidewall gratings [3], patterning of germanium on the surface [4] or lateral metal gratings [6]. Light outcoupling towards the surface of the ICL has been demonstrated with vertical-cavity surface-emitting lasers [6].
Highlights
In contrast to the azimuthal polarization of ring quantum cascade lasers, we observe a radial polarization of the projected nearfield of ring interband cascade lasers
The demand for compact, portable, and energy-efficient laser sources for selective measurements of trace gases leads to the development of different device concepts
While interband laser diodes1 dominate in the lower wavelength region up to 3.3 lm, the quantum cascade laser2 (QCL) has become a well-established laser source from 3 lm up to the THz spectral range
Summary
Martin Holzbauer,1,a) Rolf Szedlak,1 Hermann Detz,1,2 Robert Weih,3,4 Sven Ho€fling,3,5 Werner Schrenk,1 Johannes Koeth,4 and Gottfried Strasser1 We demonstrate interband cascade lasers fabricated into ring-shaped cavities with vertical light emission through the substrate at a wavelength of k % 3.7 lm. These findings underline the fundamental physical difference between light generation in interband and intersubband cascade lasers, offering new perspectives for device integration.
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