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Raman injection laser


Stimulated Raman scattering is a nonlinear optical process that, in a broad variety of materials, enables the generation of optical gain at a frequency that is shifted from that of the incident radiation by an amount corresponding to the frequency of an internal oscillation of the material1,2. This effect is the basis for a broad class of tunable sources known as Raman lasers2,3. In general, these sources have only small gain ( 10-9 cm W-1) and therefore require external pumping with powerful lasers, which limits their applications. Here we report the realization of a semiconductor injection Raman laser designed to circumvent these limitations. The physics underlying our device differs in a fundamental way from existing Raman lasers3,4,5,6,7,8: it is based on triply resonant stimulated Raman scattering between quantum-confined states within the active region of a quantum cascade laser that serves as an internal optical pump—the device is driven electrically and no external laser pump is required. This leads to an enhancement of orders of magnitude in the Raman gain, high conversion efficiency and low threshold. Our lasers combine the advantages of nonlinear optical devices and of semiconductor injection lasers, and could lead to a new class of compact and wavelength-agile mid-and far-infrared light sources.

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Figure 1: Diagrams showing the Raman effect and the band structure design.
Figure 2: Spectral characteristics.
Figure 3: Power output and temperature dependence.


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We thank C. Gmachl for many discussions. A.B. acknowledges support from the TAMU TITF Initiative.

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Correspondence to Mariano Troccoli or Alexey Belyanin.

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Troccoli, M., Belyanin, A., Capasso, F. et al. Raman injection laser. Nature 433, 845–848 (2005).

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