In this article, we present a 300-GHz wireless link composed of a photonic uni-traveling-carrier diode transmitter and an active electronic receiver based on millimeter wave integrated circuits fabricated in an InGaAs metamorphic high electron mobility transistor technology. The input pseudorandom binary sequence is transmitted and analyzed offline using fast analog-to-digital converters. The data transmission reaches ,100 Gb/s over a distance of 15 m. Complex modulation formats, such as 32-quadrature amplitude modulation and 64-quadrature amplitude modulation, are successfully transmitted up to a symbol rate of 8 GBd. The system presents not only high linearity but is also capable of transmitting high symbol rates, up to 40 GBd. To the best of the authors' knowledge, this represents the highest ever reported transmission bandwidth as well as the highest spectral density symbol rate product for transmissions with center frequency in the terahertz band. Thus, the usage of such links in future bandwidth-hungry applications, such as data centers, data showers, fronthaul, and backhaul, is proven feasible.