Abstract: This disclosure provides an ultra-compact and highly stable and efficient optical measurement system based on principals of optical absorption spectroscopy using substantially collinear pathways. It improves on such an emitter for gas sensing applications and utilizes it in a differential path-length configuration, in which two separate paths have different optical absorption coefficients by an analyte gas or molecule. The combination of two-color emission from the same source as well as two separate path lengths provides four independent measurements that can measure molecular concentration while cancelling out system fluctuations from temperature, humidity, stress, device aging, power, spectral shifts, as well as other environmental factors mechanics that would otherwise interfere with the measurement and limit sensitivity or require significant additional calibration.

Abstract: A device emitting mid-infrared light that comprises a semiconductor substrate of GaSb or closely related material. The device can also comprise epitaxial heterostructures of InAs, GaAs, AISb, and related alloys forming light emitting structures cascaded by tunnel junctions. Further, the device can comprise light emission from the front, epitaxial side of the substrate.

Abstract: A device emitting mid-infrared light that comprises a semiconductor substrate of GaSb or closely related material. The device can also comprise epitaxial heterostructures of InAs, GaAs, AlSb, and related alloys forming light emitting structures cascaded by tunnel junctions. Further, the device can comprise light emission from the front, epitaxial side of the substrate.

Abstract: A device emitting mid-infrared light that comprises a semiconductor substrate of GaSb or closely related material. The device can also comprise epitaxial heterostructures of InAs, GaAs, AlSb, and related alloys forming light emitting structures cascaded by tunnel junctions. Further, the device can comprise light emission from the front, epitaxial side of the substrate.