Abstract:In this study, we present an innovative three-dimensional (3D) heterogeneously integrated photoreceiver, which is optimized for analog microwave optical links that demand both wide bandwidth and high input optical power. The key of this design is the uni-traveling-carrier photodiode (UTC-PD), which has been flip-chip integrated onto a microwave integrated circuit submount. This integration approach enhances the photoreceiver"s overall performance, making it ideally suitful for applications requiring wide bandwidth and high power handling capabilities. The material doping and epitaxial processes of the UTC photodiode were optimized to augment its power endurance. Meanwhile, the responsivity of the photodiode was improved through the adoption of an integrated back-illuminated lens complemented by the addition of a metallic reflective layer. By establishing a precise model of the photodiode, we have refined the bandwidth characteristics of the photoreceiver using impedance compensation and broadband matching circuit design techniques. Flip-chip bonding the photodiode chip onto the microwave integrated circuit chip has substantially mitigated the impact of interconnect circuits on high-frequency performance. Furthermore, the thermal conductivity and high-power resilience of the detector chip were enhanced via gold-tin alloy micro-bump interconnections and the design of a high thermal conductivity substrate layer. The three-dimensional heterogeneous integrated photoreceiver features a 1-dB bandwidth of 42 GHz, an RF return loss exceeding 11 dB, a responsivity surpassing 0.85 A/W, a dark current below 50 nA, and a saturated input optical power of over 120 mW.By leveraging the distinctive properties of the UTC-PD, our three-dimensional (3D) heterogeneous integrated photoreceiver design achieves superior efficiency and responsiveness, positioning it as a leading solution for cutting-edge microwave photonics applications.