By Tom Whitfield, Chip Dispatch

Chip-Scale VCSEL Array Pushes Indoor Optical Wireless Past 360 Gbps

A 5×5 array of vertical-cavity surface-emitting lasers (VCSELs) transmitted a combined 362.7 gigabits per second across a two-meter free-space link, according to research published this month in Advanced Photonics Nexus. The paper, authored by Hossein Safi and eleven co-authors, ranks the result among the highest data rates ever reported for any chip-scale optical wireless transmitter paired with a free-space receiver.

What does the laser array actually contain?

Each VCSEL in the array operates as an independent data channel. The channels delivered individually between roughly 13 and 19 gigabits per second, depending on the modulation scheme in use. Twenty-one of the array's twenty-five lasers carried traffic during testing, and the combined 362.7 Gbps figure reflects their parallel operation.

The chip itself measures less than one millimeter on a side. Vertical-cavity surface-emitting lasers are the same class of device that data-center optical interconnects and consumer-facing 3D-sensing modules already rely on. Standard semiconductor fabrication processes produce them, which keeps a clear manufacturing path to high volume.

How do the beams stay separate at room scale?

Running many lasers at once creates an obvious problem: their beams can overlap and interfere with one another. The researchers addressed the issue with a custom optical front end placed in front of the chip.

A microlens array first collimates light from each VCSEL. Downstream lenses then organize the beams into a square grid at the receiver plane. Measurements showed more than 90 percent uniformity across the illuminated area at the two-meter test distance. The arrangement lets each beam serve a separate user or device in the same room.

In a four-beam test, each link held stable and produced a combined 22 gigabits per second with no significant cross-interference.

How does the energy use compare to Wi-Fi?

The system consumed about 1.4 nanojoules per bit of transmitted data. That figure sits at roughly half the energy per bit of leading Wi-Fi technologies measured under comparable conditions. The advantage reflects the inherent efficiency of laser emitters and the absence of high-power radio-frequency amplification.

Power efficiency matters because indoor wireless traffic continues to climb. Radio-based networks scale poorly as more devices come online, and the energy cost of pushing higher data rates through congested spectrum keeps rising.

Where does this sit in the wireless landscape?

The authors point out that the trial ran up against the bandwidth of a commercial photodiode receiver. A faster detector, they note, would let the same laser chip push beyond the 362.7 Gbps mark without any hardware change.

The team frames the technology as a complement to Wi-Fi and cellular rather than a replacement. Planned form factors include ceiling-mounted panels, integrated lighting fixtures, and compact access points for offices, hospitals, data centers, and public venues. Built on established VCSEL manufacturing, the platform offers a realistic route into next-generation indoor connectivity that scales with bandwidth rather than with radio-frequency congestion.

What could pull demand forward?

Indoor optical wireless targets the bandwidth ceiling that Wi-Fi 6E and Wi-Fi 7 are already brushing up against in dense offices and data-center adjacencies. If commercial photodetectors catch up to the speeds the laser chip can support, the next round of trials will likely push the headline figure well past 400 Gbps in the same form factor.