The performance of quantum well infrared detectors (QWIP) is inherently limited by the low efficiency of their optical coupling. To overcome this core challenge, this study proposed and fabricated a quantum well detector based on metal optical microcavities (MC-QWIP). Through the collaborative design of the microcavity resonance mode and the absorption characteristics of the quantum well, near-theoretical-limit absorption of incident light is achieved at the device level, thereby significantly improving the external quantum efficiency. Experimental measurements show that the peak responsivity of the prepared MC-QWIP at a wavelength of \(\:11.3\:{\upmu\:}\text{m}\) reaches 2.2 A/W, which is more than 9 times higher than that of the traditional 45° facet devices. The corresponding peak external quantum efficiency reaches 23.6%, with an absorption quantum efficiency as high as 90.8%. Micro-reflectance characterization of the device reveals a significant reduction in reflectance near the operating wavelength, providing direct evidence of near-perfect optical absorption in this spectral region. Further simulation analysis confirms that metallic absorption is effectively suppressed at the operating wavelength, indicating that optical absorption is predominantly concentrated within the active region and converted into photocurrent. This mechanism is key to achieving high external quantum efficiency. The proposed MC-QWIP architecture not only significantly improves photoelectric quantum efficiency and device sensitivity, but also establishes a robust “optical microcavity–quantum well” co-design paradigm, offering a promising pathway for the development of next-generation optoelectronic devices with high efficiency.
