High-brightness quantum cascade laser spectrometers based on master-oscillator-power-amplifier arrays

The talk will focus on advances in high brightness single longitudinal/transverse mode master oscillator power amplifier (MOPA) QCls and MOPA QCL arrays capable of broadband tuning, as well as on low-divergence high brightness QCLs with plasmonic collimators. Specifically we will report on multi-wavelength arrays of master-oscillator power-amplifier quantum cascade lasers operating at wavelengths between 9.2 and 9.8 μm. All elements of the high-performance array feature longitudinal (spectral) as well as transverse single-mode emission at peak powers between 2.7 and 10 W at room temperature. High output power and excellent beam quality render the arrays highly suitable for stand-off spectroscopy applications. I will also discuss our approach to reduce the divergence and improve beam quality of high power QCLs using plasmonic collimators. High peak power in excess of 3.5 Watt with divergence angles not exceeding 2.5 deg in the vertical and 5 deg in the horizontal direction has been achieved in an 8 micron wavelength QCL by integrating a one dimensional plasmonic collimator on the facet of a device with a narrow 0.5 mm straight section and a 2.5 mm long 1 degree tapered adiabatic beam expansion section. Importantly the fabrication of collimator on the 10 micron wide facet does not produce any deterioration in output power. I will discuss plans to integrate our novel collimator designs on the facet of QCL MOPAs.