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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. 

We report a detailed examination of multiple negative differential conductance (NDC) features with hysteresis, observed in interband cascade lasers and light emitting diodes made from six different wafers covering an emission wavelength range from 2.7 to about 7 μm. These features arise from resonant tunneling in quantum wells (QWs), can be observed in both forward and reverse biases, and persist up to 160 K and over 300 K, respectively. By comparing features from wafers with a variable number of cascade stages (Ns) and different electron injector doping concentrations, strong correlations are established between the Ns and the number of NDC peaks, as well as between the appearance of forward-bias NDC features and the doping concentration. Under reverse bias, two distinct groupings of NDC peaks appear, which can be plausibly attributed to resonant tunneling through both ground and excited states in QWs. By comparing different internal structures, this tunneling can be isolated to the cascade stages of the emitters. NDC analysis is also shown to be useful as a tool for diagnosing partial internal damage within devices, providing a simple non-destructive way to test device performance. 

Abstract Social rejection profoundly affects well-being. How do features of people’s real-world social networks relate to responses to social exclusion? People central in social networks—e.g. who have many friends—may be less distressed by exclusion, since they have many sources of support, or more sensitive to it, if they are more attuned to social feedback. We characterized a village’s social network; a subset of residents (N = 74) completed a functional magnetic resonance imaging (fMRI) study involving social exclusion in groups characterized by varying social relationships (spouses, friends, strangers). Highly-central individuals reported greater distress during exclusion by strangers, and their distress ratings scaled with responses in brain regions associated with social pain, negative affect, and mentalizing. Thus, while social connectedness is often considered a protective factor that promotes well-being, these findings suggest a potential ironic effect of social connectedness–vulnerability to distress in particular social contexts. This sensitization to exclusion could constitute an adaptive tendency to promote long-term wellness. 

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. 

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. 

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.