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1. Low threshold, high temperature operation of continuous wave interband cascade lasers near 5 μ m

   https://doi.org/10.1063/5.0228654  

   Lin, Yuzhe; Ma, Yuan; Zheng, Wanhua; Zhang, Kedong; Lu, Hong; Yang, Rui Q (September 2024, Applied Physics Letters)

   We report significant improvements in threshold current density and maximum operating temperature in continuous wave (CW) operation of interband cascade lasers (ICLs) near 5 μm. The uncoated ICLs were demonstrated at room temperature with a threshold current density of 343.8 A/cm2 and an output power of 31 mW/facet at 25 °C in CW mode. Different ICLs made from the same wafer were compared to study the impact of device dimensions on performance. The threshold current density of 331 A/cm2 achieved from a facet-uncoated 5 mm-long device at 25 °C is the lowest among all previously reported room temperature CW ICLs with emission wavelengths longer than 4 μm. Compared to the previous record of 480 A/cm2 at 4.75 μm for a facet-coated 4-mm-long ICL at 25 °C, this value of 331 A/cm2 is reduced by 31%, representing a substantial improvement. Benefited from improved device fabrication and enhanced thermal dissipation, the maximum CW operating temperature of the device reached 66 °C, which is the highest ever reported for ICLs with similar emission wavelengths. 

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2. Continuous wave interband cascade lasers near 13  μ m

   https://doi.org/10.1116/6.0003365  

   Shen, Yixuan; Yang, Rui Q; Hawkins, S D; Muhowski, A J (March 2024, Journal of Vacuum Science & Technology B)

   We report the demonstration of continuous-wave interband cascade lasers (ICLs) near 13 μm. The attained lasing wavelength of 13.2 μm at 92 K stands as the longest cw emission wavelength ever reported for III-V interband lasers. This achievement is attributed to the adoption of an innovative quantum well (QW) active region comprising strained InAs0.5P0.5 layers in contrast to the commonly used “W” QW active region, showing the potential of the modified QW active region with InAsP layers in improving device performance and extending wavelength coverage of ICLs. 

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3. Low Threshold, Long Wavelength Interband Cascade Lasers With High Voltage Efficiencies

   https://doi.org/10.1109/JQE.2023.3314098  

   Massengale, Jeremy A; Shen, Yixuan; Yang, Rui Q; Hawkins, Samuel D; Muhowski, Aaron J (December 2023, IEEE Journal of Quantum Electronics)

   We report on the substantial advancement of long wavelength InAs-based interband cascade lasers (ICLs) utilizing advanced waveguides formed from hybrid cladding layers and targeting the 10-12 μm wavelength region. Modifications in the hole injector have improved carrier transport in these ICLs, resulting in significantly reduced threshold voltages (Vth) as low as 3.62 V at 80 K. Consequently, much higher voltage efficiencies were observed, peaking at about 73% at 10.3 μm and allowing for large output powers of more than 100 mW/facet. Also, low threshold current densities (Jth) of 8.8 A/cm2 in cw mode and 7.6 A/cm2 in pulsed mode near 10 μm were observed; a result of adjustments in the GaInSb hole well composition intended to reduce the overall strain accumulation in the ICL. Furthermore, an ICL from the second wafer operating at a longer wavelength achieved a peak voltage efficiency of 57% at 11.7 μm, with a peak output power of more than 27 mW/facet. This ICL went on to lase beyond 12 μm in both cw and pulsed modes, representing a new milestone in long wavelength coverage for ICLs with the standard W-QW active region. 

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4. Pushing the performance limits of long wavelength interband cascade lasers using innovative quantum well active regions

   https://doi.org/10.1063/5.0162500  

   Shen, Yixuan; Massengale, J A; Yang, Rui Q; Hawkins, S D; Muhowski, A J (July 2023, Applied Physics Letters)

   We report significantly enhanced device performance in long wavelength interband cascade lasers (ICLs) by employing a recently proposed innovative quantum well (QW) active region containing strained InAsP layers. These ICLs were able to operate at wavelengths near 14.4 μm, the longest ever demonstrated for III–V interband lasers, implying great potential of ICLs to cover an even wider wavelength range. Also, by applying the aforesaid QW active region configuration on ICLs at relatively short wavelengths, ICLs were demonstrated at a low threshold current density (e.g., 13 A/cm2 at 80 K) and at temperatures up to 212 K near 12.4 μm, more than 50 K higher than the previously reported ICLs with the standard W-shape QW active region at similar wavelengths. This suggests that the QW active region with InAsP layers can be used to improve device performance at the shorter wavelengths. 

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5. Multiple negative differential conductance peaks in interband cascade lasers

   https://doi.org/10.1063/5.0317426  

   Steward, John D; Shen, Yixuan; Yang, Rui Q; Mishima, Tetsuya D; Santos, Michael B (February 2026, Applied Physics Letters)

   We report multiple negative differential conductance (NDC) features observed under both forward and reverse bias voltages in hybrid-cladding interband cascade lasers (ICLs). The ICL with an emission wavelength of 2.77 μm at 300 K has a threshold current density of 183 A/cm2, which is lower than previously reported values from type-II ICLs at similar and somewhat longer wavelengths. The number of NDC peaks aligns with the number of cascade stages and the current densities of the peaks are below 100 and 1 mA/cm2 for reverse and forward bias voltages, respectively, with a peak to valley current ratio of 1.8 and 1.7, respectively, at 80 K. These NDC features are observable at temperatures above 400 K under reverse bias and up to 160 K under forward bias. Hysteresis was observed with these NDC features. Since the unique features discovered in this work are inherently correlated with resonant tunneling in quantum well structures and interband transitions in ICLs, they may help improve understanding of carrier transport dynamics and provide insights into further development of ICLs as well as other potential applications. 

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