Mid-infrared resonant cavity light emitting diodes operating at 4.5 µm

We report on a mid-infrared resonant cavity light emitting diode (RCLED) operating at the wavelength of 4.5 µm with a narrow spectral linewidth at room temperature. Compared to a reference LED without a resonant cavity, our RCLED exhibits (85x) higher peak intensity, (13x) higher integrated output power, (16x) narrower spectral linewidth and (7x) superior temperature stability. The device consists of a one-wavelength thick micro-cavity containing an Al 0.12 In 0.88 As/InAs 0.85 Sb 0.15 quantum well active region sandwiched between two high contrast AlAs 0.08 Sb 0.92 /GaSb distributed Bragg reflector mirrors, grown lattice–matched on GaSb by molecular beam epitaxy. The high spectral brightness, narrow linewidth and superior temperature stability are attractive features, enabling these devices to be used for detection of N 2 O at 4.5 µm. We show that with only minor adjustments the gases CO 2 (4.2 µm) and CO (4.6 µm) are also readily accessible.