One of the unique features of parallel optic chips is the fact that they can simultaneously send and receive data. The Holey Optochip capitalizes on that feature, for its record-setting performance.
The "Holey" in the name comes from the fact that the team started with a standard silicon CMOS chip, but bored 48 holes into it. These allow optical access to its inside back surface, where 24 separate receiver and transmitter channels are located - for a total of 48 channels. Each of those channels has its own dedicated VCSEL (vertical cavity surface emitting laser) and photodetector, which are used respectively for sending and receiving data. The chip is designed to be coupled to a multimode fiber array, via a microlens optical system.