The mid-infrared (MIR) spectral range, covering mid-wave (MWIR, 3 to 5 μm) and long-wave (LWIR, 8 to 14 μm) regions, is crucial for technologies like gas sensing, bioimaging, and environmental monitoring. However, detecting MIR light challenging due to low photon energies.
Traditional MIR detectors need cryogenic cooling, increasing their size, cost, and risk of failure. In contrast, thermal detectors (bolometers) work at ambient temperatures but have reduced detection bandwidth. Recent advancements include nanoparticle-on-resonator schemes, luminescent nanotransducers, charge-density-wave materials, and innovative photodetectors. These aim to prove MIR detection speed, scalability, and cost-effectiveness.
In this scope, researchers from Yale University study the detection of mid-infrared (MIR) light using two-dimensional metal halide perovskites (2D-MHPs) at ambient temperature.
Guo Research Group Yale University Propose The use of 2D Metal Halide Perovskites at Ambient Temperature for MID Detection
Their study highlights the use of two-dimensional metal halide perovskites due to their lo thermal conductivity and strong temperature-dependent excitonic resonances, allowing for optical detection of MIR light with high sensitivity. Sensitivities down to sub-10 picowatts per square micrometer were achieved using plastic substrates and photonic enhancement strategies.
Metal halide perovskites (MHPs) are promising solution-processable semiconductors for photovoltaics and optoelectronics due to their strong electron-phonon interactions, which affect photoluminescence and facilities the formation of polarons. 2 MHPs, a diverse subclass, exhibit favorable optoelectronic properties, including dielectric and quantum confinements, leading to exciton formation and strong optical absorption. Although their ultralow thermal conductivity (k) is typically unfavourable for optoelectronic applications, it is leveraged there, along with strong temperature-dependent exciton-lattice interactions, for a new application in thermal-type MIR photodetection.
This novel application in MIR thermal detection was demonstrated with PEA ((PEA)2PbI4 ) as a model 2D-MHP. The scheme proved competitive with other methods for broadband MIR detection, overcoming bandgap limitations. Stability testing showed enhanced durability with compact dielectric layer but rapid degradation with air exposure. Potential future advancements include hybrid materials with lower thermal conductivity and higher temperature coefficient of resistance (TCR), extending to MIR imagers and multiplexed detection. The detection range may expand into far-infrared and terahertz with appropriate optical resonators.
Iceblink and Boreal for the Optical Characterization of 2D Metal Halide Perovskites
In the study of the optical characterisation of 2D-MHPs, Mid-infrared (MIR) detection measurements were conducted using supercontinuum lasers, providing broadband output from 2.2 to 4.8 μm. These lasers, with high repetition rates, were treated as continuous-wave sources due to their rapid thermal response time. Various band-pass filters selected the MIR light wavelengths for the samples. An optical chopper controlled the MIR beam frequency. For 10.6 μm measurement, a continuous-wave CO2 gas laser was used.
Furthermore, for the study on the sensitivity enhancement by membrane-based structures, and all-optical detection system comprised the Iceblink Supercontinuum Laser and the Boreal Tunable Accessory for precise and stable measurements (Figure 1 and Figure 2). FYLA’s technology generated probe pulses with a narrow spectral width (~8 nm full width at half maximum) that reflected off the sample and were captured to measure changes included by MIR light. This approach enable accurate and sensitive detection of MIR light, enhancing the capability of detectors based on 2D-MPHs.
FYLA’s Supercontinuum Lasers of Supreme Detection Measurements
In the optical characterization of detectors, using a robust broadband light source with superior power stability is crucial. It ensures consistent and accurate measurement, minimizing errors due to fluctuations in light intensity.
This stability allow for reliable comparisons and reproducible results, which are essential for developing and validating high-performance optical detectors. Furthermore, a stable light source enhances the sensitivity and accuracy of the detection system, enabling more precise analysis of the detector’s performance across different wavelengths.
In this particular MIR detector study, Yale’s option of choice was the Iceblink, which emitted ultra short pulses <10 ps with emissions from 450 to 2300 nm combined with the Boreal filter, for the selection of wavelengths in the VIS range down to resolution of ~8 nm. Iceblink’s power stability of <0.5% in std dev contributed to the meticulous performance of MIR detector analysis.
As well as Yale’s research group, we invite you to try out our Iceblink Supertontinuum Laser. Get your white light source with its unable accessory instantly delivered to your lab and forget about aligning multiple lasers, power fluctuations and additional calibration; focus on what really matters: Your research experiments.
