Monolithic reflector-integrated waveguide photodetector with optical mesa isolation

•To enhance the ability of waveguide to concentrate optical energy on the photosensitive mesa and alleviate the tradeoff between bandwidth and quantum efficiency of a photodetector. A novel waveguide photodetector with optical isolation between the photosensitive mesa and N-contact mesa, and a monolithically integrated reflector separated from the N-contact-mesa at the end of the waveguide was proposed.•The properties of the proposed structure were analyzed and simulated, and the results show that the structure can alleviate the tradeoff between bandwidth and quantum efficiency. To achieve a responsivity of 0.55 A/W, the bandwidth of the proposed structure can be improved by 28.7% compared to that of the traditional structure.•The response spectrum of the proposed structure is expected to cover the optical communication bands of ~1.55 μm and ~1.61 μm. The proposed structure may find applications in broadband high-power photo-receivers or radio-frequency transmitters with low power consumption. Moreover, this work can also be applied to different photodiode designs. Herein, we propose a monolithic reflector-integrated waveguide photodetector with optical isolation between photosensitive mesa and N-contact mesa for achieving a high efficiency bandwidth product. In the proposed photodetector, the photosensitive mesa is optically isolated but electrically connected with the N-contact mesa; this is achieved by etching a portion of the core layer to form a groove on each side of the photosensitive mesa, enhancing the binding of the waveguide to optical power. Furthermore, a mesa is formed separate from the N-contact mesa at the end of the waveguide, and the metal film is deposited to act as a mirror, thereby increasing the effective absorption length of the device. Consequently, the mutual tradeoff between the bandwidth and quantum efficiency of the photodetector could be alleviated.