Smart glasses need compact, efficient displays that can produce detailed images without drawing too much power. Laser beam scanning is one approach to meeting these requirements. Rather than using a fixed array of pixels, these displays steer a laser beam across the field of view, building an image point by point. Higher-resolution images can be produced without increasing the size of the optical components by switching colors more rapidly while using a fast-scanning mirror. Current systems, however, face limits in how quickly and efficiently they can control laser color.
To produce full-color images, laser beam scanning displays combine red, green, and blue laser light into a single output beam. Conventional systems control the intensity of each color by changing the electrical current supplied to its laser diode. Direct current modulation has a more limited bandwidth than external optical modulation, restricting how quickly colors can change and, in turn, the achievable imaging resolution. Laser diodes must also operate above a threshold current to produce sufficient intensity, which increases power consumption.
As reported in Advanced Photonics Nexus , Yasuhiro Takagi and colleagues at TDK Corporation developed a photonic chip that addresses these limitations by controlling the laser light with voltage rather than continually changing the current supplied to the lasers. Instead, electrical voltages applied to the chip regulate the intensity of the red, green, and blue light before the three colors are combined into a single output beam.
The researchers fabricated the device using a thin film of lithium niobate, a material with optical properties that can be controlled electrically. The chip incorporates three Mach–Zehnder interferometers, one for each primary color. These structures split and recombine light so that an applied voltage controls the intensity passing through each channel. A multiplexer formed from lithium niobate waveguides then brings the three colors together into one beam.
In experiments, the researchers controlled the individual color channels through the voltage applied to the chip. Combining the channels allowed the system to generate full-color output. The researchers also integrated the device with a MEMS scanning mirror, demonstrating its potential for producing full-color images in a laser beam scanning system.
Speed was a central part of the study. The chip achieved a modulation bandwidth of 10 gigahertz, which the researchers report is sufficient for 4K resolution and higher. By moving rapid color control away from direct modulation of the laser diodes, the approach addresses one of the factors limiting the resolution of conventional laser scanning displays.
The voltage-controlled design also substantially reduced energy use. The researchers found that the system could cut overall power consumption by more than 75 percent compared with the conventional approach. Because light intensity can be controlled by the photonic circuit rather than by maintaining high laser currents, the design also removes the need for neutral-density filters used to reduce excess laser output.
Together, these changes address several interconnected challenges in miniaturizing laser scanning displays: switching speed, power consumption, and the number of optical components required. The researchers conclude that the thin-film lithium niobate circuit improves the feasibility of combining high-resolution imaging with the small form factor needed for smart glasses. The demonstrated 10-GHz bandwidth and full-color generation provide experimental evidence that external voltage control can support ultracompact laser beam scanning displays.
Further improvements will focus on reducing optical losses as light passes through the lithium niobate waveguides and as the three colors are combined. Lower losses could increase the overall efficiency of the system and strengthen the case for integrating this type of photonic circuit into compact wearable displays.
For details, see the original Gold Open Access article by Y. Takagi et al., “ Thin-film lithium niobate photonic integrated circuit for laser beam scanning imaging ," Adv. Photon. Nexus 5(6), 066007 (2026), doi: 10.1117/1.APN.5.6.066007
Advanced Photonics Nexus
Thin-film lithium niobate photonic integrated circuit for laser beam scanning imaging
18-Sep-2026