Orthogonal Sampling with a Single Photodiode

For communication at higher data rates [1], the electrical processing of high-bandwidth signals poses several challenges including high energy consumption, bandwidth limitations, clock jitter, etc. With orthogonal optical sampling, instead, high bandwidth signals can be down-converted to parallel low-bandwidth signals, allowing processing with low-bandwidth electronics [2]. For numerous applications, like data centers, access networks, and handheld devices, direct detection (DD) orthogonal sampling [3] is particularly useful considering the simple hardware requirements, and unlike coherent detection, it does not need a local oscillator (LO). Nevertheless, for DD an optical filter (OF) [4] with the bandwidth of the data signal is essential for detecting the broadband signal with a photodiode, which strongly influences the overall system performance.