Stefan Menzel

Widely tunable mid-infrared quantum cascade lasers using sampled grating reflectors.

We demonstrate a three-section, electrically pulsed quantum cascade laser which consists of a Fabry-Pérot section placed between two sampled grating distributed Bragg reflectors. The device is current-tuned between ten single modes spanning a range of 0.46 μm (63 cm(-1)), from 8.32 to 8.78 μm. The peak optical output power exceeds 280 mW for nine of the modes.

Quantum cascade laser master-oscillator power-amplifier with 1.5 W output power at 300 K.

Quantum cascade laser (QCL) master oscillator power amplifiers (MOPAs) reaching output power levels of P=1.5W at room temperature were realized. We discuss results and describe directions for future QCL MOPA design.

High-power arrays of quantum cascade laser master-oscillator power-amplifiers.

We 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. The performance of two arrays that are based on different seed-section designs is thoroughly studied and compared. High output power and excellent beam quality render the arrays highly suitable for stand-off spectroscopy applications.

Master-oscillator power-amplifier quantum cascade laser array

We report on the demonstration of an array of master-oscillator power-amplifier quantum cascade lasers (QCLs) operating in single-mode at different wavelengths between 9.2 and 9.8 μm. In each device, the output of a distributed feedback QCL is injected into a tapered QCL section which acts as an amplifier while maintaining a high beam quality due to adiabatic mode spreading. All array elements feature longitudinal as well as transverse single-mode emission at peak powers between 0.8 and 3.9 W at room temperature. The high output power and excellent beam quality render the array highly suitable for stand-off spectroscopy applications.

Single-mode tapered quantum cascade lasers

We demonstrate tapered quantum cascade lasers monolithically integrated with a distributed Bragg reflector acting as both a wavelength-selective back mirror and a transverse mode filter. Each of the 14 devices operates at a different wavelength between 9.2 and 9.7 μm, where nine devices feature single-mode operation at peak powers between 0.3 and 1.6 W at room temperature. High output power and excellent beam quality with peak brightness values up to 1.6 MW cm−2 sr−1 render these two-terminal devices highly suitable for stand-off spectroscopy applications.

Gratings with an aperiodic basis: single-mode emission in multi-wavelength lasers

We propose a new class of gratings having multiple spatial frequencies. Their design relies on the use of small aperiodic grating sequences as unit cells whose repetition forms a superlattice. The superlattice provides well- defined Fourier components, while the choice of the unit cell structure enables the selection, modulation or suppression of certain Fourier components. Using these gratings to provide distributed feedback in mid-infrared quantum cascade lasers, we demonstrate simultaneous lasing on multiple well-defined and isolated longitudinal modes, each one having a sidemode suppression ratio of about 20dB.

Double-waveguide quantum cascade laser

We demonstrate 1.1 W peak power at room-temperature from a double-waveguide quantum cascade laser (QCL) grown by metal-organic chemical vapor deposition. Two full broadband QCL active regions were grown on top of each other separated by thick cladding layers to reduce gain competition. Simultaneous lasing on Fabry-Perot modes separated by as much as 360 cm−1 is obtained. This design paves the way for high-brightness broadband mid-infrared sources, as well as more complex three-terminal devices.

Quantum cascade laser master oscillator power amplifier with 1.5W output power at T=300K

Quantum cascade laser (QCL) master oscillator power amplifiers (MOPAs) reaching output power levels of P=1.5W at room temperature were realized. We discuss results and describe directions for future QCL MOPA design.