Continuous-wave operation of vertically emitting ring interband cascade lasers at room temperature

Funding: The authors are grateful for financial support received under Austrian Research Promotion Agency (FFG) project No. 1516332 (ATMO-SENSE).We present vertical light emission in continuous-wave mode from an interband cascade laser (ICL) at a record temperature of up to 38 °C. These results pave the way toward a more efficient and compact integration of this technology in mobile spectroscopic applications. Our approach employs ring cavity ICLs that are mounted epi-side down for efficient heat extraction from the devices. The vertical single-mode emission relies on a metallized second-order distributed-feedback grating designed for an emission wavelength of 3.8 μm. A single lateral mode operation is favored by a narrow waveguide width of 4 μm. Optical output powers of more than 6 mW were measured at 20 °C for rings with a diameter of ∼800 μm. At this temperature, the threshold current-density amounted to 0.60 kA/cm2 and the device showed continuous current and temperature tuning rates of 0.06 nm/mA and 0.37 nm/K, respectively.Publisher PDFPeer reviewe

Pushing the room temperature continous-wave operation limit of GaSb-based interband cascade lasers beyond 6 μ\mum

We present GaSb-based interband cascade lasers emitting at a center wavelength of 6.12 $\mu$m at 20$^\circ$C in continuous-wave operation up to a maximum operating temperature of 40$^\circ$C. Pulsed measurements based on broad area devices show improved performance by applying the recently published approach of adjusting the GaInSb layer thickness in the active region to reduce the valence intersubband absorption. The W-quantum well design adjustment and the optimization of the electron injector, to rebalance the electron and hole concentrations in the active quantum wells, improved the device performance, yielding room temperature current densities as low as 0.5 kA/cm$^2$ for broad area devices under pulsed operation. As a direct result of this improvement the long wavelength limit for GaSb-based ICLs in continuous wave operation could be extended. For an epi-side down mounted 23 $\mu$m wide and 2 mm long device with 9 active stages and high-reflectivity back facet the threshold power is below 1 W and the optical output power is over 25 mW at 20$^\circ$C in continuous-wave mode. Such low-threshold and low-power consumption interband cascade lasers are especially attractive for mobile and compact sensing systems

Substrate-emitting ring interband cascade lasers

The authors acknowledge the support by the Austrian Science Fund (FWF) projects P26100-N27 (H2N) and NextLite (F4909-N23), and the State of Bavaria. HD acknowledges financial support through an APART fellowship from the Austrian Academy of Sciences.We demonstrate interband cascade lasers fabricated into ring-shaped cavities with vertical light emission through the substrate at a wavelength of λ ≈ 3.7 µm. The out-coupling mechanism is based on a metallized second-order distributed feedback grating. At room-temperature, a pulsed threshold current-density of 0.75 kA/cm2 and a temperature-tuning rate of 0.3 nm/°C is measured. In contrast to the azimuthal polarization of ring quantum cascade lasers, we observe a radial polarization of the projected nearfield of ring interband cascade lasers. These findings underline the fundamental physical difference between light generation in interband and intersubband cascade lasers, offering new perspectives for device integration.Publisher PDFPeer reviewe

Double-waveguide interband cascade laser with dual wavelength emission

We are grateful for receiving financial support within the BMBF Project “LASELO” (FKZ: 13N13773).Interband cascade lasers (ICLs) with dual wavelength emission have been realized by utilizing two spatially separated active regions in the same device. The two wavelengths (3.1 and 3.7 µm) were chosen in order to demonstrate that the usual spectral gain bandwidth of an ICL can be overcome. At 20°C, threshold current densities as low as 215 A/cm² (short wavelength) and 158 A/cm² (long wavelength) could be achieved in pulsed mode. It was possible for an epi-up mounted device to maintain dual-wavelength continuous-wave emission up to 0°C. Despite the longer wavelength emission being suppressed at higher temperatures, the shorter wavelength maintained an output power of more than 10 mW at 15°C.PostprintPeer reviewe

Interband cascade laser arrays for simultaneous and selective analysis of C1-C5 hydrocarbons in the petrochemical industry

Funding: European Union Horizon 2020 research and innovation programme under grant agreement No 636930 (iCspec).The detection and measurement of hydrocarbons is of high interest for a variety of applications, for example within the oil & gas industry from extraction throughout the complete refining process, as well as for environmental monitoring and for portable safety devices. This paper presents a highly sensitive, selective and robust tunable laser analyzer that has the capability to analyze several components in a gas sample stream. More specifically, a multi-gas system for simultaneous detection of C1 to iC5 hydrocarbons, using a room temperature distributed feedback interband cascade laser array, emitting in the 3.3 micrometer band has been realized. It combines all the advantages of the tunable laser spectroscopy method for a fast, sensitive and selective in-line multicomponent tunable laser analyzer. Capable of continuous and milliseconds fast monitoring of C1-iC5 hydrocarbon compositions in a process stream, the analyzer requires no consumables (e.g. purging, carrier gas) and no in-field calibration, enabling a low cost of ownership for the analyzer. The system was built, based on an industrial GasEye series platform and deployed for the first time in field at Preem refinery in Lysekil, Sweden in autumn 2018. Results of the measurement campaign and comparison with gas chromatography instrumentation is presented.PostprintPeer reviewe

Application of antimonide diode lasers in photoacoustic spectroscopy

First investigations of photoacoustic (PA) spectroscopy (PAS) of methane using an antimonide semiconductor laser are reported. The laser fabrication is made in two steps. The structure is firstly grown by molecular beam epitaxy, then a metallic distributed-feedback (DFB) grating is processed. The laser operates at 2371.6 nm in continuous wave and at room temperature. It demonstrates single-mode emission with typical tuning coefficients of 0.04 nm mA-1 and 0.2 nmK-1. PA detection of methane was performed by coupling this laser into a radial PA cell. A detection limit of 20 ppm has been achieved in a preliminary configuration that was not optimised for the laser characteristics. © 2004 Elsevier B.V. All rights reserved

Novel Helmholtz-based photoacoustic sensor for trace gas detection at ppm level using GaInAsSb/GaAlAsSb DFB lasers

A new and compact photoacoustic sensor for trace gas detection in the 2-2.5 μm atmospheric window is reported. Both the development of antimonide-based DFB lasers with singlemode emission in this spectral range and a novel design of photoacoustic cell adapted to the characteristics of these lasers are discussed. The laser fabrication was made in two steps. The structure was firstly grown by molecular beam epitaxy then a metallic DFB grating was processed. The photoacoustic cell is based on a Helmholtz resonator that was designed in order to fully benefit from the highly divergent emission of the antimonide laser. An optimized modulation scheme based on wavelength modulation of the laser source combined with second harmonic detection has been implemented for efficient suppression of wall noise. Using a 2211 nm laser, sub-ppm detection limit has been demonstrated for ammonia. © 2005 Elsevier B.V. All right reserved

DFB Lasers Between 760 nm and 16 μm for Sensing Applications

Recent years have shown the importance of tunable semiconductor lasers in optical sensing. We describe the status quo concerning DFB laser diodes between 760 nm and 3,000 nm as well as new developments aiming for up to 80 nm tuning range in this spectral region. Furthermore we report on QCL between 3 μm and 16 μm and present new developments. An overview of the most interesting applications using such devices is given at the end of this paper

Amplification of GaSb-Based Diode Lasers in an Erbium-Doped Fluoride Fibre Amplifier

Building upon recent advances in GaSb-based diode lasers and Er-doped fluoride fibre technologies, this article demonstrates for the first time the fibre-based amplification of mid-infrared diode lasers in the wavelength range around 2.78 $\mu$m. The laser setup consists of a GaSb-based diode laser and a single-stage Er-doped fibre amplifier. Amplification is investigated for continuous wave (CW) and ns-pulsed input signals, generated by gain-modulation of the GaSb-based seed lasers. The experimental results include the demonstration of output powers up to 0.9 W, pulse durations as short as 20 ns, and pulse repetition rates up to 1 MHz. Additionally, the amplification of commercial and custom-made GaSb-based seed lasers is compared and the impact of different fibre end-cap materials on laser performance is analysed