Quantum Cascade Lasers operating between 5.7 and 5.9 μm have been integrated on to a Germanium-on-Silicon (GoS) platform by flip-chip bonding. Sensing in this wavelength region is useful for a wide range of applications from monitoring caffeine and sweeteners, to analysis of oestrogen composition, which plays an important role in the metastatic spread of breast cancer. The approach demonstrated here uses laser bars incorporating twenty-four separate laser sources. Further enhancements of this system from the first generation are presented, including real-time power monitoring of the QCL output via fibrecoupling, more efficient gratings, improved support-structures and process improvements for both the QCL and GoS.
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