Ultrafast one-chip optical receiver with functional metasurface

nm-thick i-InGaAs absorption layer sandwiched by p/n- doped InGaAs and indium phosphide (InP) layers (see Supplementary Fig. 1a for the detailed profile). The PDA and MS layers of our platform enable unique properties unattainable with conventional surface-normal receivers. First, the membrane InGaAs/InP p-i-n PD provides efficient opto-electric (O-E) conversion in the 1550-nm wavelength band with ultralow capaci- tance and high electrical conductivity, resulting in ultrahigh O-E bandwidth exceeding 100 GHz53,54. Second, the Si MS layer offers Fig. 1 | One-chip optical receiver platform with an integrated Si metasurface and membrane InGaAs photodetector array. a Schematic illustration of our receiver platform, where ultrathin amorphous-Si (α-Si) metasurface (MS) and high-speed membrane InGaAs photodetector (PD) layers are integrated on both sides of a transparent SiO2 substrate. Spatially parallelized input signals are incident from the MS side and focused onto arrayed PDs. The MS offers various advanced functionalities, including focusing, splitting, and polarization manip- ulation, as shown in the right inset. The left inset shows the InGaAs/InP p-i-n structure of the high-speed membrane PD, which is directly bonded on the other side of the substrate. S signal, G ground. b Schematics of four types of receivers demonstrated in this work. (i) Single-channel metalens (ML)-integrated PD. (ii) ML-integrated PD array (PDA) to detect parallel signals from a multi-core fiber (MCF). (iii) Stokes-vector receiver (SVR) with an integrated MS that sorts input light to four different polarization bases (P1, P2, P3, and P4) and focuses them on a four-channel PDA. (iv) Coherent receiver (CR) with an integrated MS that splits input light to four polarization states (a, b, r, and l) and focuses them on a four- channel PDA. The signal and local oscillator (LO) light from a single-mode fiber (SMF) are incident on the MS with x and y orthogonal polarizations, so that in- phase and quadrature (IQ) components of the signal can be retrieved from the four photocurrents. c Photograph of the receiver chip fabricated on a 1.2-cm- squared SiO2 substrate, which contains 94 receivers with four different configurations. Article https://doi.org/10.1038/s41467-025-65984-6 Nature Communications| (2025) 16:10070 2