OWC WDM and Coherent Transmission Using IMOS Surface Grating Coupler for Light Collection

The receivers for Optical Wireless Communication (OWC) need to meet the requirements for high-capacity data transmission. Photonic Integrated Circuits (PIC) allow the separation of light collection and light detection. In this way, both can be optimized separately. Light can be coupled into a PIC from free space through a surface grating coupler and detected with a high-speed photodiode. This separation enables additional processing of light between the collection and detection. Thus, increasing the throughput of data transmission is possible by placing wavelength demultiplexers or coherent receivers. In this work, we demonstrate light collection with a 15 μ m by 15 μ m surface grating coupler with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$8^{\circ }$</tex-math></inline-formula> field of view fabricated on an Indium-Phosphide Membrane on a Silicon (IMOS) platform in combination with commercial devices to achieve very high wireless data transmission rates. The OWC is achieved by focusing a collimated beam with 3 mm diameter on the surface grating coupler by a 50-mm focal length lens. We show optical wireless transmission of collimated light over a distance of 10 cm of error-free 100 Gbps WDM of four 25 Gbps NRZ OOK channels, and 45 GBaud 64-QAM single-channel coherent transmission.