Monolithically, widely tunable quantum cascade lasers based on a heterogeneous active region design.
Quantum cascade lasers (QCLs) have become important laser sources for accessing the mid-infrared (mid-IR) spectral range, achieving watt-level continuous wave operation in a compact package at room temperature. However, up to now, wavelength tuning, which is desirable for most applications, has relied on external cavity feedback or exhibited a limited monolithic tuning range. Here we demonstrate a widely tunable QCL source over the 6.2 to 9.1 μm wavelength range with a single emitting aperture by integrating an eight-laser sampled grating distributed feedback laser array with an on-chip beam combiner. The laser gain medium is based on a five-core heterogeneous QCL wafer. A compact tunable laser system was built to drive the individual lasers within the array and produce any desired wavelength within the available spectral range. A rapid, broadband spectral measurement (520 cm(-1)) of methane using the tunable laser source shows excellent agreement to a measurement made using a standard low-speed infrared spectrometer. This monolithic, widely tunable laser technology is compact, with no moving parts, and will open new opportunities for MIR spectroscopy and chemical sensing.
Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA.
Wenjia
W
Zhou
Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA.
Neelanjan
N
Bandyopadhyay
Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA.
Donghai
D
Wu
Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA.
Ryan
R
McClintock
Center for Quantum Devices, Department of Electrical Engineering and Computer Science, Northwestern University, Evanston, IL 60208, USA.
Manijeh
M
Razeghi