Article

Dispersion-compensated wavelength beam combining of quantum-cascade-laser arrays.

MIT Lincoln Laboratory, Lexington, Massachusetts 02420, USA.
Optics Express (Impact Factor: 3.53). 12/2011; 19(27):26725-32. DOI: 10.1364/OE.19.026725
Source: PubMed

ABSTRACT A multiwavelength array of distributed feedback (DFB) quantum cascade lasers (QCLs) that spans λ = 8.28 to 9.62 μm is wavelength beam combined (WBC) using both single-grating and dual-grating designs. WBC with a single grating results in a pointing error of 3-times the beam divergence for a single laser and arises from the nonlinear dispersion of the grating. By adding a second grating to compensate for the nonlinear dispersion, the pointing error is reduced to only 13% of the beam divergence for a single laser. A transceiver based on the dual-grating-WBC QCL was used to measure the transmittance of a polymer sheet placed between itself and a retroreflector over a round-trip distance of 70 meters.

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