Tiny laser array could offer faster, greener indoor wireless
Most wireless data today travels through radio-based technologies such as Wi-Fi and cellular systems. While these approaches have been highly successful, they face mounting challenges, including crowded radio spectrum, interference in dense indoor spaces, and rising energy consumption as more devices come online.
A promising complementary approach is optical wireless communication. Light offers far more bandwidth than radio frequencies, does not interfere with existing wireless systems, and can be directed precisely at specific locations. These features make optical wireless links particularly attractive for indoor environments
Now in a study reported in Advanced Photonics Nexus, a team of British researchers from the Universities of Cambridge and Manchester and companies Integrated Compound Semiconductors Ltd and Compound Semiconductor Ctr. Ltd have demonstrated a compact optical wireless transmitter that combines very high data rates with improved energy efficiency.
The system is built around a small chip containing an array of tiny semiconductor lasers and a carefully designed optical setup that shapes how light is delivered to users. Together, these elements form a scalable platform for high-capacity indoor wireless communication.
At the heart of the system is a custom-made 5 × 5 array of infrared VCSELs. In this work, each laser in the array is individually addressable and can transmit its own data stream. By operating many lasers in parallel, the researchers were able to increase the total data capacity far beyond what a single light source could deliver. The entire laser array fits on a chip less than a millimetre in size, making it compatible with compact wireless access points or even can be easily integrated into devices like smartphones.
The team fabricated the laser array using established semiconductor processes and mounted the finished chip onto a custom circuit board. Initial tests showed that the lasers performed consistently across the array, producing stable output power and supporting high-speed modulation.
To evaluate performance, the researchers set up a free-space optical link spanning two meters. Each laser was driven using a modulation technique that divides the data into many closely spaced frequency channels, allowing the system to make efficient use of the available bandwidth while adapting to variations in signal quality.
In the experiments, 21 of the 25 lasers were operational. Individual lasers achieved data rates between about 13 and 19 Gbps. When combined, the system reached an aggregate data rate of 362.7 Gbps. This represents one of the highest reported throughputs for a chip-scale optical wireless transmitter using a free-space coupled receiver.
The researchers note that the achieved speeds were limited by the bandwidth of the commercial photodetector used in the measurements. With faster receivers, the same transmitter architecture could support even higher data rates.
Sending many beams of light at once introduces new challenges. If beams overlap too much, signals can interfere with one another, making it difficult for receivers to separate the data streams. To address this, the team designed a compact optical system that shapes and steers the light emitted by the laser array.
A custom microlens array first collimates the light from each laser. Additional lenses then redistribute the beams into a structured grid of square illumination spots at the receiver plane. This arrangement ensures that each beam covers a defined area with minimal overlap.
Measurements showed that the shaped beams achieved more than 90 percent uniformity across the illuminated region at a distance of two meters. This structured illumination makes it possible to assign different beams to different users or devices in the same room.
The researchers also tested multiuser operation by activating several lasers simultaneously. In a demonstration with four active beams, each link maintained stable communication, and the system delivered a combined data rate of about 22 gigabits per second. The results show that multiple optical wireless links can operate in parallel without significant interference.
Lower energy use per bit
Energy efficiency is a key concern for future wireless networks, especially as data traffic continues to grow. Traditional radio-based systems require increasing amounts of power to deliver higher data rates, which can become costly and environmentally burdensome.
The optical wireless system demonstrated here uses laser sources that are naturally power efficient and can be driven directly at high speed. As a result, the energy required to transmit each bit of data is significantly lower than in typical Wi-Fi systems. The researchers measured an energy consumption of about 1.4 nanojoules per bit, roughly half that reported for state-of-the-art Wi-Fi under comparable conditions.
The researchers emphasise that optical wireless communication is not intended to replace Wi-Fi or mobile networks, but to complement them. Optical links could be deployed in rooms, offices, factories, or other indoor spaces where high capacity is needed, offloading traffic from crowded radio networks.
In the future, similar systems could be integrated into lighting fixtures, ceilings, or access points, providing fast, secure, and energy-efficient wireless connections to many users at once. By combining laser arrays, high-speed data transmission, and carefully designed optics in a compact platform, this work outlines a practical path toward next-generation indoor wireless networks that deliver higher performance without a corresponding increase in energy use.
Reference
H. Safi et al., 'Chip-scale beam-shaped optical wireless system for high-speed and energy-efficient connectivity'; Adv. Photon. Nexus 5(2) 026008 (2026),
