University of Illinois engineers develop the first eye-safe, room-temperature photonic crystal laser using silicon dioxide, advancing PCSEL technology for LiDAR, optical communication, and more.
Photonic crystal surface-emitting lasers (PCSELs) have long held the promise of revolutionizing laser technology. Known for producing highly directional, bright laser beams with pinpoint accuracy, PCSELs are ideal for next-generation applications like LiDAR, high-speed optical communication, autonomous vehicle sensors, and advanced defense systems.
However, for over a decade, a fundamental design issue has held this technology back—until now.
The PCSEL Problem: Fragile Air Holes
Traditionally, PCSELs rely on air holes in the photonic crystal layer to manipulate light behavior. These holes are critical for controlling the laser’s emission properties. But during semiconductor regrowth—a necessary process to complete the laser structure—those delicate air holes collapse as atoms naturally move in and fill them, ruining the photonic structure and rendering the laser nonfunctional.
The Innovative Fix: Embedding Silicon Dioxide
In a major breakthrough, engineers at the University of Illinois Urbana-Champaign (UIUC) have replaced the fragile air holes with a more durable solution—silicon dioxide (SiO₂), a stable dielectric material often referred to as “glass” in electronics.
By embedding silicon dioxide into the photonic crystal layer, they successfully created the first room-temperature, eye-safe, photopumped PCSEL using buried dielectric features. This innovation maintains the crystal’s integrity during regrowth and eliminates the longstanding fabrication bottleneck.
Overcoming New Challenges: Growing Semiconductors on Glass
While the silicon dioxide solution prevented collapse, it introduced a new hurdle: semiconductors don’t typically grow well on amorphous (non-crystalline) materials like SiO₂.
“The first time we tried to regrow the dielectric, we didn’t know if it was even possible,” said Erin Raftery, lead researcher and engineering student at UIUC.
Despite the odds, the team carefully controlled the regrowth process. By guiding the semiconductor material to grow laterally around the dielectric and merge at the top—a technique called coalescence—they preserved the necessary crystal structure.
Results: A Functional, Eye-Safe PCSEL at Room Temperature
The result is a buried dielectric PCSEL that operates at room temperature and emits light at a wavelength safe for the human eye—a milestone achievement in photonic laser technology.
This is the first-ever demonstration of such a laser, paving the way for commercial, scalable, and durable PCSEL devices.
What’s Next: From Photopumped to Electrically Powered
Currently, the device operates via optical pumping, meaning it requires an external laser to initiate function. While this proves the concept, real-world applications demand electrically injected PCSELs that can run on standard power supplies.
The UIUC team’s next goal is to integrate electrical contacts into the design, creating electrically powered PCSELs suitable for mass production and deployment.
Why This Matters
This development could reshape the future of:
- LiDAR systems for autonomous vehicles
- High-speed optical communication networks
- Precision sensing in defense and aerospace
- Compact, low-power laser devices
With enhanced durability, simplified manufacturing, and the potential for electrical operation, silicon dioxide-embedded PCSELs may soon become the new standard in high-performance laser technology.