Optically Induced Fast Wavelength Modulation In A Quantum Cascade Laser

An optically induced fast wavelength shift is demonstrated in a standard middle infrared (MIR) quantum cascade laser (QCL) by illuminating the front facet with a femtosecond (fs) near infrared (NIR) laser, allowing fast optical frequency modulation (FM) for free space optical communication (FSOC) and FM spectroscopy. Using an etalon as a narrow band-pass wavelength filter, the wavelength modulation (WM) was clearly observed at frequencies up to 1.67 GHz. This approach can also be used for wavelength conversion and might be extended to QCLs operating in different wavelength regions. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457871]