An optical device and a method for fabricating an optical device are described. The optical device may be a light emitting diode (LED) device, e.g. a micro-LED (μLED) device, or a photodiode (PD) device, e.g. an imager. The method comprises processing, on a first semiconductor wafer, an array including a plurality of compound semiconductor LEDs or compound semiconductor PDs and a plurality of first contacts, each first contact being electrically connected to one of the LEDs or PDs. The method further comprises processing, on a second semiconductor wafer, a CMOS IC and a plurality of second contacts electrically connected to the CMOS IC. The method further comprises hybrid bonding the first semiconductor wafer to the second semiconductor wafer such that the plurality of LEDs or PDs are individually connected to the CMOS IC via the first and second contacts.