We demonstrate a monolithic all-epitaxial resonant-cavity architecture for long-wave infrared photodetectors with substrate-side illumination. An nBn detector with an ultra-thin ([Formula: see text]) absorber layer is integrated into a leaky resonant cavity, formed using semi-transparent highly doped ([Formula: see text]) epitaxial layers, and aligned to the anti-node of the cavity's standing wave. The devices are characterized electrically and optically and demonstrate an external quantum efficiency of ∼25% at [Formula: see text] in an architecture compatible with focal plane array configurations.

We present a spectrally selective, passively cooled mid-wave infrared bolometric absorber engineered to spatially and spectrally decouple infrared absorption and thermal emission. The structure leverages an antenna-coupled metal–insulator–metal resonance for mid-wave infrared normal incidence photon absorption and a long-wave infrared optical phonon absorption feature, aligned closer to peak room temperature thermal emission. The phonon-mediated resonant absorption enables a strong long-wave infrared thermal emission feature limited to grazing angles, leaving the mid-wave infrared absorption feature undisturbed. The two independently controlled absorption/emission phenomena demonstrate decoupling of the photon detection mechanism from radiative cooling and offer a new design approach enabling ultra-thin, passively cooled mid-wave infrared bolometers.

We use a Michelson interferometer to explore the spectroscopic properties of laser diode emission over a wide range of operational conditions. By studying how the interferogram changes with drive current, we demonstrate the relationship between coherence length and spectral bandwidth. At low injection current, the laser source operates more like an ordinary light-emitting diode (LED), generating a relatively broad spectrum with short coherence length. In contrast, when the drive current exceeds the single-mode lasing threshold, we obtain a steady sinusoidal interferogram throughout the movable mirror scanning range, indicative of monochromatic light. At intermediate injection, we observe a beating pattern due to the presence of multiple longitudinal lasing modes. We verify that the beat distance, or optical travel between beats, is consistent with the spectrally validated mode spacing.

We explore distributed Bragg reflectors leveraging a reduction in the refractive index of highly-doped InAs due to free carrier effects.<br>

We explore distributed Bragg reflectors leveraging a reduction in the refractive index of highly-doped InAs due to free carrier effects.<br>