Quantum cascade lasers: from tool to product

Abstract

The quantum cascade laser (QCL) is an important laser source in the mid-infrared and terahertz frequency range. The past twenty years have witnessed its tremendous development in power, wall plug efficiency, frequency coverage and tunability, beam quality, as well as various applications based on QCL technology. Nowadays, QCLs can deliver high continuous wave power output up to 5.1 W at room temperature, and cover a wide frequency range from 3 to 300 μm by simply varying the material components. Broadband heterogeneous QCLs with a broad spectral range from 3 to 12 μm, wavelength agile QCLs based on monolithic sampled grating design, and on-chip beam QCL combiner are being developed for the next generation tunable mid-infrared source for spectroscopy and sensing. Terahertz sources based on nonlinear generation in QCLs further extend the accessible wavelength into the terahertz range. Room temperature continuous wave operation, high terahertz power up to 1.9 mW, and wide frequency tunability form 1 to 5 THz makes this type of device suitable for many applications in terahertz spectroscopy, imaging, and communication.

Terahertz Frequency Metrology for Spectroscopic Applications: a Review

“…In this regard, a very promising kind of source is based on intracavity difference frequency generation between two mid-IR QCLs [200]. These sources are currently the only semiconductor sources that are able to emit multi-mW power and cover the entire 1-5 THz range at room temperature [201,202]. Wide-range frequency tuning spanning several THzs at room temperature based on composite distributed feedback (DFB) QCL arrays [203,204], or external cavity technique [205], has been demonstrated.…”

Quantum Cascade Lasers: Electrothermal Simulation

“…Much higher WPE and/or output power has been achieved at lower temperatures or at pulsed mode [7,14] near 4.8 µm. A summary of recent developments can be found in review papers [8,15].…”

Theory and measurements of harmonic generation in semiconductor superlattices with applications in the 100 GHz to 1 THz range

“…Recent photomixer concepts can reach this range, but emitted powers fall drastically with increasing frequency [12]. Difference frequency generation via resonant optical nonlinearities pumped by a mid-infrared (MIR) QCL [13] is a promising approach for on-chip simultaneous emission from the MIR to the THz range but would require GHz resonances, which are not easily achievable per design. Optical combs show strong promise for the MIR range [14], but their efficient coverage of the GHz to THz ranges is still to be demonstrated.…”