Advanced mid-infrared lightsources above and beyond lasers and their analytical utility

Abstract

In the mid-infrared (MIR) spectral range, a series of applications have successfully been shown in the fields of sensing, security and defense, energy conservation, and communications. In particular, rapid and recent developments in MIR light sources have significantly increased the interest in developing MIR optical systems, sensors, and diagnostics especially for chem/bio detection schemes and molecular analytical application scenarios. In addition to the advancements in optoelectronic light sources, and especially quantum and interband cascade lasers (QCLs, ICLs) largely driving the increasing interest in the MIR regime, also thermal emitters and light emitting diodes (LEDs) offer opportunities to alternatively fill current gaps in spectral coverage specifically with analytical applications and chem/bio sensing/diagnostics in the focus. As MIR laser technology has been broadly covered in a variety of articles, the present review aims at summarizing recent developments in MIR non-laser light sources highlighting their analytical utility in the MIR wavelength range. Graphical abstract

Application of Two-Dimensional Materials towards CMOS-Integrated Gas Sensors

“…The most critical component for NDIR gas sensors is the emitter, as it must be able to provide the specific range of wavelengths dependably. These typically come in three flavors: Microbulb lamps, MEMS microheaters, and light-emitting diodes (LEDs) [ 83 ]. The microbulb lamp is essentially a thermal emitter and the wavelength which is produced can only be controlled by the produced temperature of the emitter element.…”

“…The most recent low-power and low-cost push toward design solutions for NDIR emitters has been the LED design. Advances in semiconductor fabrication and introduction of novel materials have made it possible to develop light-emitting diodes in the IR spectrum [ 83 ]. These types of emitters come with the benefit of improved signal-to-noise ratio, improved accuracy, less stabilization issues, and potential for CMOS-friendly fabrication [ 79 ].…”

“…The structure of the LED emitters is quite different from conventional photodiodes, which are based on electron–hole recombination. The requirement of a narrow bandgap material increases Auger recombination, reducing the efficiency at the high carrier injection levels required for occupancy inversion [ 83 ]. To overcome this, the light from these LEDs is achieved by recombining electrons and holes in heterostructures, similar to interband cascade lasers.…”

Photoreflectance Analysis of InAsPSb/InGaAs Multi-Quantum Well LED Structures with Different Well/Barrier Numbers

“…Various compound materials have been extensively studied to enhance the efficiency of QW LED structures in the MWIR range, primarily falling into two categories: II-VI and III-V compounds. Some examples of these investigations include GeSn/Ge [7], GeSn/SiGeSn [8], AlInAs/InAs [9], GaN/AlGaN [10], and InAs/GaSb [11] QW structures. Considerable focus has also been directed toward InAs and its alloys, including InAsPSb, InGaAs, InAsSb, and InGaAsSb, as highly promising materials for crafting optoelectronic devices in the infrared wavelength region [12][13][14][15][16].…”

Development of LTCC IR-Emitter and Its Packaging

“…The samples illuminated with MIR radiation gives the response based on the rotational and vibrational resonances. 1 Hence the spectrum is referred as the "molecular fingerprint" enabling the detection and quantification of molecular compounds in health, medical, environmental, defence, surveillance, automotive production, gas sensing and industrial applications. Demand for IR emitters is also expected to surge and growth market is also expected to accelerate in coming years.…”