A device and related fabrication method is provided for an organic/inorganic hybrid optical amplifier with a function of converting infrared light to visible light. The hybrid device integrates an inorganic heterojunction phototransistor (HPT), an embedded metal electrode mirror with a dual function as an optical mirror and charge injection electrode, and an organic light emitting diode (OLED). This integrated optical amplifier is capable of amplifying the incoming light and producing light emission with a power greater than that of the incoming signal. In the second aspect of the invention, the optical amplifier is capable of detecting an incoming infrared electromagnetic wave and converting the wave back to a visible light wave. The optical device has dual functions of optical power amplification and photon energy up-conversion. The optical amplifier device consists of an InGaAs/InP based HPT structure as photodetector, gold-coated metals as embedded mirror and a top-emission OLED. New optical up-conversion imaging devices are also provided that include focal-point array of the organic/inorganic hybrid optical amplifier devices in pixelated formats. The up-conversion imaging devices have a fast response time to enable gated operation for practical applications such as night vision, active surveillance, semiconductor wafer inspection and eye-safe infrared imaging. More importantly, the up-conversion imaging devices would be particularly useful for detecting ultra-low intensity infrared scenes.