Fig. 1: Concept of optical circuit switching (OCS) using a photonic chip-based Si3N4 soliton microcomb and semiconductor optical amplifiers (SOAs).
From: Ultrafast optical circuit switching for data centers using integrated soliton microcombs
a Interconnection of 64 racks via an arrayed waveguide grating router (AWGR) for implementing fast OCS. In this model, distinct wavelengths are assigned to each rack at each time slot. At each receiver, a 10–20 nanosecond (ns) time slot is assigned for each rack on a round-robin basis for data transmission. The switching module is placed on the top of rack (TOR) switch. A single comb source that is post amplified via cascaded amplifiers to attain high optical power per line can be distributed among many racks. The 64 individual combs (comb1, ..., comb 64) split from a central frequency comb generator (FCG) can be distributed across 64 different racks as a multiwavelength laser, making this architecture more power-efficient and flexible. The multiple data-carrying optical carriers are routed using a passive AWGR to the assigned racks. b Each comb channel is transmitted to SOAs after de-multiplexing, where a control signal (turning on/off current) is applied to switch between the comb channels at sub-ns. The comb channels (10-ns slots) are encoded with data using Mach-Zehnder modulators (MZMs) and transmitted to the relevant racks. The multiple MZMs shown here indicate that this architecture can be scaled further to establish links between more racks. c The multi-wavelength source based on the chip-scale soliton microcomb is generated by pumping with a single laser. Microscope images of a Si3N4 microresonator (d) and a photonic chip (e) containing an AWG and SOAs. The inset in (d) shows a false color SEM image of a Si3N4 microresonator’s coupling section.
