High-responsivity and high-speed black phosphorus photodetectors integrated with proton exchanged thin-film lithium niobate waveguides.

We present a high-performance broadband (450-1550 nm) black phosphorus photodetector based on a thin-film lithium niobate waveguide. The waveguides are fabricated by the proton exchange method with flat surfaces, which reduces the stress and deformation of two-dimensional materials. At a wavelength of 1550 nm, the photodetector simultaneously achieves a high responsivity and wide bandwidth, with a responsivity as high as 147 A/W (at an optical power of 17 nW), a 3-dB bandwidth of 0.86 GHz, and a detectivity of 3.04 × 1013 Jones. Our photodetector exhibits one of the highest responsivity values among 2D material-integrated waveguide photodetectors.

Design and epitaxy of 1.5 microm InGaAsP-InP MQW material for a transistor laser.

An InGaAsP-InP transistor laser (TL) at 1.55 microm has been designed and modeled. The proposed TL has a deep-ridge waveguide structure with the multiple quantum wells (MQWs) buried in the base-emitter junction, which provides good optical and electrical confinement and can effectively reduce the optical absorption and lateral leakage current. Good laser performance has been predicted by numerical modeling based on which the epitaxial growth was carried out by metalorganic chemical vapor deposition (MOCVD). The effect of p-dopant (Zn) diffusion on the QW performance was investigated by a re-growth procedure. By introducing a graded p-doping profile, the Zn diffusion into the MQWs was effectively controlled. With an average doping density of 1 x 10(18) cm(-3) in the base contact layer, the InGaAsP MQWs demonstrated high PL intensity at 1.51 microm and clear satellite diffraction peaks in the XRD spectrum.